Cholestasis.doc

Cholestasis

Definisi: penghentian atau supresi aliran empedu, dengan penyebab intrahepatik atau ekstrahepatik

Etiologi

Within the Liver: Causes include acute hepatitis, alcoholic liver disease, primary biliary cirrhosis with inflammation and scarring of the bile ducts,

cirrhosis due to viral hepatitis B or C ), drugs, hormonal effects on bile flow during pregnancy (a condition called cholestasis of pregnancy (see ),

and cancer that has spread to the liver.

Outside the Liver: Causes include a stone in a bile duct, narrowing (stricture) of a bile duct, cancer of a bile duct, cancer of the pancreas, and

inflammation of the pancreas (pancreatitis).

Causes Obstructive cholestasis

o Biliary atresia

o Congenital bile duct anomalies (choledochal cysts)

o Cholelithiasis

o Primary sclerosing cholangitis

o Infectious cholangitis (cholangitis)

o Cholangitis associated with Langerhans cell histiocytosis

o Cholestasis with ductal paucity

o Alagille syndrome

o Nonsyndromic ductal paucity

o Ductopenic allograft rejection

Hepatocellular cholestasis

o Hepatitis (hepatitis A, hepatitis B, hepatitis C)

o Alpha1-antitrypsin deficiency

o Inborn errors of bile acid synthesis

o Drug-induced cholestasis

o Total parenteral nutrition (TPN)–associated cholestasis

o Progressive familial intrahepatic cholestasis

Patofisiologi

1. Hepatoselular → terjadi kesalahan saat pembentukan empedu

Adanya empedu dalam sel hepatosit dan sel kanalikuli, ada hubungannya dengan asam kolat

2. Obstruktif → terjadi kesulitan aliran empedu saat empedu sudah terbentuk

SymptomsJaundice, dark urine, light-colored stools, and generalized itchiness are characteristic symptoms of cholestasis. Jaundice results from excess

bilirubin deposited in the skin, and dark urine results from excess bilirubin excreted by the kidneys. Retention of bile products in the skin may

cause itching, with subsequent scratching and skin damage. Stools may become light-colored because the passage of bilirubin into the intestine

is blocked. Stools may contain too much fat (a condition called steatorrhea) because bile cannot enter the intestine to help digest fat in foods.

Fatty stools may be foul-smelling. The lack of bile in the intestine also means that calcium and vitamin D SOME TRADE NAMES

SEE ERGOCALCIFEROL

are poorly absorbed. If cholestasis persists, a deficiency of these nutrients can cause loss of bone tissue. Vitamin K, which is needed for blood

clotting, is also poorly absorbed from the intestine, causing a tendency to bleed easily.

Prolonged jaundice due to cholestasis produces a muddy skin color and fatty yellow deposits in the skin. Whether the person has other

symptoms, such as abdominal pain, loss of appetite, vomiting, or fever, depends on the cause of cholestasis.

DiagnosisA doctor tries to determine whether the cause is within or outside the liver on the basis of symptoms and the results of a physical examination.

Recent use of drugs that can cause cholestasis suggests a cause within the liver. Small, spiderlike blood vessels visible in the skin, an enlarged

spleen, and fluid in the abdominal cavity (ascites), which are signs of chronic liver disease, also suggest a cause within the liver.

Findings that suggest a cause outside the liver include certain kinds of abdominal pain (such as intermittent pain in the upper right side of the

abdomen and sometimes also in the right shoulder ) and an enlarged gallbladder (felt during the physical examination or detected by imaging

studies).

Some findings do not indicate whether the cause is within or outside the liver. They include heavy alcohol intake, loss of appetite, nausea, and

vomiting.

Typically, the blood levels of two enzymes, alkaline phosphatase and gamma-glutamyl transpeptidase, are very high in people with cholestasis. A

blood test that measures the level of bilirubin indicates the severity of the cholestasis but not its cause. An imaging study, usually

ultrasonography, is almost always done if blood test results are abnormal. Computed tomography (CT) or sometimes magnetic resonance

imaging (MRI) may be done in addition to or instead of ultrasonography. If the cause appears to be within the liver, a liver biopsy (see Diagnostic

Tests for Liver, Gallbladder, and Biliary Disorders: Biopsy of the Liver) may be done and usually establishes the diagnosis. If the cause appears to

be blockage of the bile ducts, more precise images of these ducts are usually needed. Typically, either endoscopic retrograde

cholangiopancreatography (ERCP) or magnetic resonance cholangiopancreatography (MRCP) is done. MRCP uses magnetic resonance imaging

(see Symptoms and Diagnosis of Digestive Disorders: Computed Tomography and Magnetic Resonance Imaging). In ERCP, a contrast agent is

injected and x-rays are taken.

Treatment

A blockage of the bile ducts can usually be treated with surgery or endoscopy (using a flexible viewing tube with surgical instruments attached). A

blockage within the liver may be treated in various ways depending on the cause. If a drug is the suspected cause, the doctor stops its use. If

acute hepatitis is the cause, cholestasis and jaundice usually disappear when hepatitis has run its course. A person with cholestasis is advised to

avoid or stop using any substance that is toxic to the liver, such as alcohol and certain drugs.

Cholestyramine SOME TRADE NAMES

QUESTRAN

, taken by mouth, can be used to treat itchiness. This drug binds with certain bile products in the intestine, so they cannot be reabsorbed to irritate

the skin. Unless the liver is severely damaged, taking vitamin K can improve blood clotting. Supplements of calcium and vitamin D SOME

TRADE NAMES

SEE ERGOCALCIFEROL

are often taken if the cholestasis persists, but they are not very effective in preventing loss of bone tissue.

PathophysiologyThe mechanisms of cholestasis can be broadly classified into hepatocellular, where an impairment of bile formation occurs, and obstructive, where impedance to bile flow occurs after it is formed. The typical histopathologic features of hepatocellular cholestasis include the presence of bile within hepatocytes and canalicular spaces, in association with generalized cholate injury. Typical of obstructive cholestasis is bile plugging of the interlobular bile ducts, portal expansion, and bile duct proliferation in association with centrilobular cholate injury.

Bile is a highly complex water-based medium containing inorganic ions and many classes of organic amphiphiles, the formation of which involves multiple mechanisms and levels of regulation. The transport of solute into the canaliculus by specific transporters creates chemical and osmotic gradients and promotes water flow by a paracellular pathway. Several of these specific transporters have been identified, and their function has been characterized. The identification of defective transporters in some familial cholestatic disorders has led to improved understanding of the molecular mechanisms of human cholestasis. This subject was recently reviewed in depth.

Redundancies in the mechanisms of solute transport that result in bile formation are noted. From what is currently known about the process, seemingly few, if any, of the known transporters are absolutely essential in the process. Therefore, the absence or impairment of a single transporter is not expected to result in failure of bile formation. Instead, a process of amplification is required to produce clinical cholestasis. A primary mechanism of amplification is the retention of hydrophobic bile salts, strong detergents that cause membrane injury and impairment of membrane function. Retained bile salts down-regulate new bile acid synthesis, which results in a reduction of the bile salt pool and in reduced enterohepatic recirculation.

Retention of cholesterol results in increased cholesterol content of membranes that reduces their fluidity and impairs the function of integral membrane proteins. These amplification mechanisms result in further retention of damaging substances, accelerated membrane injury and dysfunction, and ultimately, generalized failure of the excretory mechanism for bile. This converging pathway makes the differentiation of cholestatic diseases on clinical grounds very difficult.

Obstructive cholestasis is usually the result of physical obstruction of the biliary system at the level of the extrahepatic bile ducts, often by a stone or tumor. However, obstruction or paucity of small bile ducts can result in functional obstruction of the entire biliary system. This may be the mechanism involved in the cholestasis observed in Alagille syndrome, which is associated with heart, skeleton, eye, kidney, and facial manifestations.

Retention of bile salts results in injury to biological membranes throughout the body. The liver is most affected. The retention of hydrophobic bile salts results in their incorporation into membranes, which alters membrane fluidity and function. Bile salt injury of hepatocyte membranes is an important amplifier of cholestasis. The retention of secondary cholestatic bile acids, such as lithocholic acid, results in further membrane injury. Bile salts may be a mediator of hepatic fibrosis as well. Injury to RBCs can result in spur-cell hemolytic anemia.

Many patients with chronic cholestasis have an asthmalike syndrome, which may be quite severe and unresponsive to conventional asthma therapy. Wheezing disappears with effective therapy of cholestasis, which suggests that it is a secondary event. The authors' opinion is that retention of bile salts results in irritation of respiratory membranes and the asthmalike picture. Patients with chronic cholestasis also have frequent nosebleeds, probably from the same mechanism. These patients may have life-threatening nosebleeds without abnormal coagulation parameters and with no clinically apparent anatomic problem in the nasal airway.

The differential diagnosis of cholestasis in neonates and infants is much broader than in older children and adults. This is because the immature liver is relatively sensitive to injury, and the response of the immature liver is more limited. Cholestasis develops in response to a wide variety of insults. Although the reasons for this are not entirely clear, it is considered the result of immaturity of several critical mechanisms of bile formation. So-called physiologic cholestasis of infancy results from immaturity of these mechanisms. This is better termed physiologic hypercholemia and is characterized by the elevation of serum bile salt concentrations in healthy infants to a level equal to many adults with pathologic cholestasis.

This developmental condition probably helps to establish the infant's sensitivity to various insults that would not produce cholestasis in adults, such as gram-negative sepsis, heart failure, metabolic disease, and exposure to minimally toxic substances.

Because of this, looking beyond the liver for the cause of cholestasis in newborns or young infants is wise. If no other cause is found and liver disease is suspected, a more focused diagnostic investigation can be undertaken.

The effects of cholestasis are profound and widespread. Although the principal effects involve the function of the liver and intestine, secondary effects can involve every organ system. The primary effects are bile retention, regurgitation of bile into serum, and reduction in bile delivery to the intestine. These result in secondary effects that lead to worsening liver disease and systemic illness. The retention of bile constituents results in 6 clinically important events.

Retention of conjugated bilirubin and its regurgitation into serum

Excretion of conjugated bilirubin is the rate-limiting step of bilirubin clearance. During cholestasis, conjugation of bilirubin continues but excretion is reduced. The mechanism by which conjugated bilirubin regurgitates into serum is unclear, but it may differ according to the disease etiology. In hepatocellular cholestasis, where bile formation is reduced, conjugated bilirubin is likely to efflux directly from the hepatocyte via diffusion or vesicular exocytosis. On the other hand, in obstructive cholestasis, conjugated bilirubin possibly enters the canalicular space and effluxes back through a weakened tight junction.

The presence of elevated serum concentration of conjugated bilirubin is a principal sign of cholestasis. It results in jaundice, which can be detected by scleral icterus at a concentration as low as 2 mg/dL, and by dark urine. The concentration of conjugated bilirubin is affected by the rate of production of bilirubin, the degree of cholestasis, and alternate pathways of elimination, principally renal excretion. The magnitude of elevation is not diagnostically important because it does not reflect the type or degree of cholestasis. For example, whereas other investigations clearly indicate that patients with neonatal giant cell hepatitis

typically have more bile flow than patients with biliary atresia, the serum conjugated bilirubin concentration is usually higher in neonatal giant cell hepatitis.1 This probably reflects an increase in bilirubin production.

Alternate elimination pathways, principally by way of the kidneys, limit the absolute elevation of conjugated bilirubin. Conjugated bilirubin concentration rarely exceeds 30 mg/dL, although such elevated levels can occur. Because conjugated bilirubin is relatively weakly bound to albumin, it can dissociate relatively easily and be filtered into the urine. The parents of children with cholestasis frequently report dark urine or a stained diaper, and examination of the urine is a useful starting point in the evaluation of an infant with jaundice.

Increased serum concentration of nonconjugated bilirubin

Increased serum concentration of nonconjugated bilirubin is present in most patients with cholestasis. The rate of bilirubin conjugation is probably reduced by end-product inhibition or as the result of hepatocyte injury. The rate of bilirubin production may also be increased as the result of hemolysis that can accompany cholestasis.

Newer methods of measuring bilirubin in serum have resulted in the discovery of a fraction of serum bilirubin that is covalently bound to albumin, known as delta bilirubin or biliprotein. This fraction may account for a large proportion of total bilirubin in patients with cholestatic jaundice but is absent in patients with nonconjugated hyperbilirubinemia. This complex is formed in plasma by a nonenzymatic process that involves acyl migration of bilirubin from its glucuronide ester with the formation of an amide linkage between 1 propionic acid side chain and a lysine residue of plasma albumin. The presence of large quantities of delta bilirubin indicates long-standing cholestasis. Any amount of delta bilirubin in cord blood or the blood of a newborn is an important sign indicating cholestasis that antedates birth.

Hypercholemia

Hypercholemia, or increased serum bile salt concentration, is a universal consequence of cholestasis. The transport of bile salts from plasma to bile is the principal driving force for bile formation. Failure to transport bile salts may be a principal mechanism of cholestasis or may be a consequence of the effects of cholestasis on hepatocyte function. In either case, the liver cell retains bile salts, resulting in down-regulation of new bile acid synthesis and in an overall reduction in the total pool size. Bile salts are regurgitated from the hepatocyte, which results in an increase in the concentration of bile salts in the peripheral circulation. Furthermore, the uptake of bile salts entering the liver in portal vein blood is inefficient, which results in spillage of bile salts into the peripheral circulation.

Reduced flux of bile salts into bile results in reduced delivery into the intestine and reduced enterohepatic recirculation. Because the movement of bile salts in the enterohepatic circulation represents the major driving force for bile formation, the degree of cholestasis is amplified by these events.

Overall, patients with cholestasis have an increase in serum concentration of bile salts, an increase in hepatocyte concentration of bile salts, a decrease of bile salts in the enterohepatic circulation, and a decrease in the total bile salt pool size.

Pruritus

One very common clinical consequence of cholestasis is pruritus. The mechanism of pruritus in liver disease is not entirely understood, and major debate concerns its relationship to the retention of bile salts. The serum or tissue concentrations of bile salts do not correlate well with the degree of pruritus, although all patients with pruritus related to liver disease have significant elevations of serum bile salts. Therapeutic approaches that reduce pruritus generally also reduce serum bile salt concentrations. Newer theories suggest that patients have differing sensitivities to elevated bile salt concentrations, which act on peripheral

pain afferent nerves to produce the sensation of itching. This stimulation involves opiate-mediated pathways, and opiate antagonists can block cholestasis-associated itching. Itching does not appear to be associated with histamine release, and antihistamine therapy is generally ineffective.

For patients with cholestasis, pruritus may be a minimal problem, or it may seriously impair the quality of life. Scratching is the most measurable effect of pruritus. The degree of pruritus can be quantitated by clinical findings related to scratching, which has been useful in monitoring patient response to therapy. Scratching leads to abrasions and skin mutilation in some patients. Secondary skin infections can occur. Constantly "scratching the unscratchable itch" has serious consequences. These children experience loss of sleep, attention deficits, poor school performance, and a form of hyperkinesis that may have importance regarding energy balance. The psychological ramifications have not been reported, but older children express helplessness and can become suicidal. Unremitting and untreatable pruritus can be an indication for liver transplantation.

The effects of pruritus are age-dependent. The authors are often asked why young infants with cholestasis do not itch. Confidently, the response is that they do itch but are developmentally incapable of scratching. Scratching involves the use of arms, forearms, and fingers in a coordinated motion that occurs at a typical frequency. The ability to scratch is not yet developed in young infants.

The cutaneous signs of scratching begin to appear, usually around the ears or the nasal bridge, in infants aged 6-7 months. From there, they expand over the head, then the trunk, and finally to the limbs by the time the baby reaches age 12-14 months. The mutilating scratching observed in older patients does not appear until well after the first birthday. The fact that young infants do not scratch does not mean that they do not itch. Cholestatic babies are often irritable and do not socialize well. Young infants with those signs almost invariably proceed to scratching as they age, and irritability probably represents their response to pruritus.

Hyperlipidemia

Hyperlipidemia is characteristic of some but not all cholestatic diseases. Serum cholesterol is elevated in cholestasis because its metabolic degradation and excretion are impaired. Bile is the normal excretory pathway for cholesterol, and with reduced bile formation, cholesterol is retained. Cholesterol retention can cause an increase in membrane cholesterol content and a reduction in membrane fluidity and membrane function, thereby amplifying the cholestasis. Furthermore, bile salts are the metabolic products of cholesterol, and in cholestasis, synthesis of bile salts is reduced. Much of plasma cholesterol is in the form of lipoprotein-X, an abnormal lipoprotein observed only in the serum of patients with cholestasis. Its centrifugation density is similar to a low-density lipoprotein, but the structure is very different. It has a high phospholipid and albumin content and a platelike rouleau structure when viewed under the electron microscope.

The marked elevation of serum cholesterol observed in children with cholestasis, which often exceeds 1,000 mg/dL and sometimes can be as high as 4,000 mg/dL, probably does not have as great an effect on the cardiovascular system as a similar elevation of low-density lipoprotein in familial hypercholesterolemia. This may be because of the packaging of cholesterol into lipoprotein-X, which lacks the surface protein constituents necessary to interact with vascular endothelium. Although it should be considered in a therapeutic strategy, the potential for cardiovascular disease is probably low. Few studies of children with chronic cholestasis have demonstrated accelerated cardiovascular disease.

The contribution of dietary cholesterol to the elevated serum cholesterol in patients with cholestasis is probably minimal, and limiting the diet in order to reduce serum cholesterol is not justified because that maneuver may have secondary effects on nutrition. Furthermore, the use of oral bile salt–binding agents, such as cholestyramine, has little effect on serum cholesterol in this setting. Agents that block the synthesis

of cholesterol have been used sparingly in cholestasis and cannot be recommended at this time. The proper approach to treating hypercholesterolemia in cholestatic liver disease is to treat the liver disease itself.

Xanthomas

Xanthomas may result from the deposition of cholesterol into the dermis. The development of xanthomas is more characteristic of obstructive cholestasis than of hepatocellular cholestasis. Xanthomas may develop rapidly over a few months in acute extrahepatic biliary obstruction. Acutely developing xanthomas are usually the eruptive type, which are white pustular lesions pinpoint to 2 mm in diameter, that appear first on the trunk and in the diaper area. See the image below.

Eruptive xanthomas. Courtesy of Duke University Medical Center.

Planar xanthomas that occur first around the eyes but also in the creases of the palms and soles and on the neck develop more slowly and are principally observed in chronic cholestasis syndromes. Finally, tuberous xanthomas are associated with very long duration of cholestasis and develop over the extensor surfaces, such as the elbows, Achilles tendons, and knees. These are unusual in pediatric patients.

Failure to thrive

One of the major clinical effects of cholestasis, particularly chronic cholestasis, is failure to thrive. The mechanisms of failure to thrive include malabsorption, anorexia, poor nutrient use, hormonal disturbances, and secondary tissue injury. Malabsorption in cholestatic liver disease results from reduced delivery of bile salts to the intestine, which results in inefficient digestion and absorption of fats. Digestion is affected because bile salts are important for the function of bile salt–dependent lipase activity and the stabilization of the lipase-colipase complex. In addition, bile salts are important in stabilization of lipid emulsions, which is important for increasing the surface area on which lipase works.

Absorption is inefficient because of reduced formation of intestinal micelles, which are important for removing the end products of lipolysis and effecting their absorption. The result of these events is the malabsorption of fat and fat-soluble vitamins.

Malabsorption of fat results in the loss of a source of calories that is important in infant nutrition. Furthermore, the delivery of fat into the colon can result in colonic secretion and diarrhea. Adults with fat malabsorption often experience anorexia. This may also occur in infants, but more often, infants take in increased amounts of formula to compensate for loss of calories. Finally, the loss of fat into the stool also results in calcium wasting through the formation of calcium soaps of fatty acids. This may play an important role in bone disease in children and adults with chronic cholestasis.

The treatment of fat malabsorption principally involves dietary substitution. In older patients, a diet that is rich in carbohydrates and proteins can be substituted for a diet containing long-chain triglycerides. In infants, substitution may not be possible, and the substitution of a formula containing medium-chain triglycerides may improve fat absorption and nutrition. This, however, has not clearly been proven, and therapeutic formulas containing medium-chain triglycerides may not be worth their expense. Bile salt

therapy to replace missing bile salts is not practical. Ursodeoxycholic acid, which is used to treat some cholestatic conditions, does not form mixed micelles and has no effect on fat absorption.

The malabsorption of fat-soluble vitamins can result in vitamin deficiency states. Vitamins E, D, K, and A are all malabsorbed in cholestasis, and in that order.2 Vitamin E deficiency can result in peripheral neuropathy and possibly hemolysis. Vitamin D deficiency results in osteomalacia and rickets. Vitamin K deficiency causes coagulopathy and possibly reduced brain development. Vitamin A deficiency does not result in clinical disease in cholestasis. In chronic cholestasis, careful attention must be paid to prevent fat-soluble vitamin deficiencies. This is accomplished by administering fat-soluble vitamins and monitoring the response to therapy.

Mortality/MorbidityCholestasis is not a primary cause of death. However, it is the cause of considerable morbidity as indicated above in Pathophysiology.

SexNo clear difference in the incidence of cholestasis between males and females is observed. Incidence is equal in most genetic diseases leading to cholestasis. However, several conditions have a female dominance, including biliary atresia, drug-induced cholestasis, and of course, cholestasis of pregnancy.

AgeCholestasis is observed in people of every age group. However, newborns and infants are more susceptible and more likely to develop cholestasis as a consequence of immaturity of the liver.

Young gestational age, low birth body weight, more sepsis episodes, and long duration of parenteral nutrition are risk factors associated with Parenteral nutrition associated cholestasis.

HistoryPatients with cholestasis may present clinically in many different ways depending on the disease process.

In most cases, scleral icterus is noted before any other sign; it may be apparent at conjugated bilirubin levels as low as 2 mg/dL.

At higher levels of conjugated bilirubin, dark urine may be noted secondary to the filtering of bilirubin into the urine.

Cutaneous jaundice may not be noted until bilirubin levels reach 5 mg/dL or higher.

In patients with cholestasis, another common presentation is severe pruritus secondary to elevated bile acids.

o At high concentrations (5 times the reference range), retained bile acids can cause maddening pruritus in which patients are unable to sleep or concentrate and may resort to cutaneous mutilation for relief.

o Infants who are unable to scratch may become very irritable in response to the pruritus. In chronic cholestasis, cholesterol deposits called xanthomas may form in the skin. This may be a visible signal of severe cholestasis. Because of the poor bile flow in patients with cholestasis, they may also have inefficient digestion and absorption of dietary fats. These patients often demonstrate failure to thrive and have problems with fat-soluble vitamin deficiency and steatorrhea.

PhysicalAs noted above, the physical signs of cholestasis are usually scleral icterus or cutaneous jaundice, or both. These patients may have physical evidence of scratching or excoriation if they also have severe bile acid retention.

Xanthomas look like small white papules or plaques and are usually found on the trunk and diaper area and in areas of friction (eg, diaper line, creases of hands, elbows, neck).

Another important physical finding in patients with cholestasis may be evidence of failure to thrive with altered anthropometrics, such as reduced height and reduced weight for height due to fat malabsorption.

Differential Diagnoses

Other Problems to Be ConsideredJaundice not due to cholestasisNonconjugated hyperbilirubinemiaDubin-Johnson syndromeRotor syndromeCarotinemiaDark urine not due to bilirubinuriaHematuriaDrug ingestionDehydrationPruritus not due to cholestasisAtopic diseaseDrug ingestionBehavior disorderXanthomatosis not due to cholestasisFamilial hypercholesterolemiaCerebrotendinous xanthomatosisMalabsorption not due to cholestasisPancreatic insufficiencyIntestinal mucosal diseasesSmall bowel bacterial overgrowthBile acid malabsorptionIleal resection

Workup

Laboratory Studies Serum bilirubin levels are elevated in virtually all patients with cholestasis. Serum direct or conjugated bilirubin levels are elevated in virtually all cholestatic diseases and not

in other diseases causing hyperbilirubinemia.

Total serum bile salt concentration levels are elevated in virtually all cholestatic diseases.

Qualitative serum and urine bile acids by mass spectroscopy are used to identify genetically determined errors in bile acid synthesis.

The total serum cholesterol level is elevated in virtually all obstructive cholestatic diseases, whereas the high-density lipoprotein (HDL) level is within the reference range or low. Total

cholesterol is within the reference range in certain hepatocellular cholestatic diseases, whereas the HDL level is within the reference range or low.

Serum lipoprotein-X levels are elevated in virtually all obstructive cholestatic diseases.

Serum alkaline phosphatase levels are elevated in virtually all obstructive cholestatic diseases and most hepatocellular cholestatic diseases.

Serum 5'-nucleotidase levels are elevated in virtually all obstructive cholestatic diseases and most hepatocellular cholestatic diseases.

Serum gamma-glutamyl transferase (GGT) levels are elevated in virtually all obstructive cholestatic diseases and many hepatocellular cholestatic diseases. A small number of hepatocellular cholestatic diseases occur in which the GGT level is within the reference range or low (eg, progressive familial intrahepatic cholestasis, inborn errors of bile acid synthesis).

Fecal fat levels are elevated in virtually all cholestatic diseases.

Imaging Studies Ultrasonography of liver and bile ducts is used to identify anatomic causes of obstructive

cholestasis (eg, choledochal cyst, gallstones). Abdominal CT scanning is used to identify anatomic causes of obstructive cholestasis (eg,

choledochal cyst, gallstones).

Biliary nuclear medicine study (ie, hepatoiminodiacetic acid [HIDA] scanning) is used to identify anatomic causes of obstructive cholestasis (eg, choledochal cyst, gallstones) and to differentiate between obstructive and hepatocellular cholestasis (ie, biliary atresia versus neonatal hepatitis).

Endoscopic retrograde cholangiography is used to identify anatomic causes of obstructive cholestasis (eg, choledochal cyst, gallstones).

Percutaneous transhepatic cholangiography is used to identify anatomic causes of obstructive cholestasis (eg, choledochal cyst, gallstones).

Procedures Liver biopsy is the single most useful test to determine the cause of cholestasis but requires a high

degree of expertise in interpretation. Exploratory surgery is a very useful tool for diagnosing neonatal cholestasis. Older literature

suggested that exploratory surgery placed patients with neonatal hepatitis at risk, but this is not the case with modern anesthesia and surgical techniques.

o If surgical disease is in question, initiate exploratory surgery to provide a definitive demonstration of bile duct anatomy.

o In institutions with less experience and expertise, perform exploratory surgery more frequently, rather than less so.

Operative cholangiography is simple, straightforward, time-efficient, and definitive.

Histologic Findings Many histologic findings are disease specific; therefore, refer to articles about disease states (see

Causes). The typical histopathologic features of hepatocellular cholestasis include the presence of bile within hepatocytes and canalicular spaces, in association with generalized cholate injury.

Typical of obstructive cholestasis is bile plugging of the interlobular bile ducts, portal expansion, and bile duct proliferation in association with centrilobular cholate injury.

Differentiating between idiopathic neonatal hepatitis and biliary atresia is a diagnostic challenge. With expert evaluation, nothing contributes as much to that differential diagnosis as the findings on percutaneous liver biopsy.

The landmark 1974 paper of Brough and Bernstein demonstrated the diagnostic usefulness of the percutaneous liver biopsy.6 In this study of 158 patients, the authors compared the original pathologic diagnosis to the ultimate diagnosis that included surgical findings and long-term follow-up. The original diagnosis was an error in 10 patients (6.3%), which makes biopsy an excellent diagnostic procedure. The type of error observed in these 10 patients was more important. In 9 of 10 misdiagnoses, the pathologic diagnosis was obstructive disease when the patient actually had neonatal hepatitis or alpha1-antitrypsin deficiency. This error led to exploratory surgery to confirm the diagnosis, which was of little harm to the patient. In only 1 patient with biliary atresia was the pathologic diagnosis that of hepatitis, which led to delay in the diagnosis of this surgical obstructive disease. Thus, in only 1 of 158 patients (0.6%) did a diagnostic error lead to meaningful clinical consequences.

Liver biopsy, therefore, has a very high sensitivity and specificity for the diagnosis of biliary atresia, with somewhat less specificity for the diagnosis of neonatal hepatitis.

Treatment

Medical CareMuch medical care in patients with cholestasis is disease specific; therefore, refer to articles about disease states (see Causes). Some medical care is specifically directed at cholestasis and its consequences.

Cholestasis often does not respond to medical therapy of any sort. Some reports indicate success in children with chronic cholestatic diseases with the use of ursodeoxycholic acid (20-30 mg/kg/d), which acts to increase bile formation and antagonizes the effect of hydrophobic bile acids on biological membranes. Phenobarbital (5 mg/kg/d) may also be useful in some children with chronic cholestasis. Opiate antagonists can block cholestasis-associated itching.

The contribution of dietary cholesterol to the elevated serum cholesterol in patients with cholestasis is probably minimal, and limiting the diet in order to reduce serum cholesterol is not justified because that maneuver may have secondary effects on nutrition. Furthermore, oral bile salt–binding agents, such as cholestyramine, have little effect on serum cholesterol in this setting. Agents that block the synthesis of cholesterol have been used sparingly in cholestasis and cannot be recommended at this time. The proper approach to treating hypercholesterolemia in cholestatic liver disease is to treat the liver disease itself.

Treatment of fat malabsorption principally involves dietary substitution. In older patients, a diet that is rich in carbohydrates and proteins can be substituted for a diet containing long-chain triglycerides. In infants, that may not be possible, and substitution of a formula containing medium-chain triglycerides may improve fat absorption and nutrition. This, however, has not clearly been proven, and therapeutic formulas containing medium-chain triglycerides may not be worth their expense. Bile salt therapy to replace missing bile salts is not practical. Ursodeoxycholic acid, which is used to treat some cholestatic conditions, does not form mixed micelles and has no effect on fat absorption.

In chronic cholestasis, careful attention must be paid to prevent fat-soluble vitamin deficiencies. This is accomplished by administering fat-soluble vitamins and monitoring the response to therapy.

Administer vitamin E as tocopherol polyethylene glycol succinate (TPGS) to achieve sufficient absorption in the setting of reduced intestinal bile salt concentrations.

Surgical Care Surgical care is disease specific; therefore, refer to articles about disease states (see Causes).

Consultations Referral to a specialist in gastroenterology or hepatology is indicated for any patient with

cholestatic liver disease, particularly if it is severe or prolonged.

Diet See Medical Care.

Medication

Choleretic agentsUrsodeoxycholic acid acts to increase bile formation and antagonizes the effect of hydrophobic bile acids on biological membranes.

Ursodeoxycholic acid (Actigall, Urso)

Shown to promote bile flow in cholestatic conditions associated with a patent extrahepatic biliary system. Decreases the cholesterol content of bile and therefore reduces bile stone and sludge formation.

Dosing

Interactions

Contraindications

Precautions

Adult

10-15 mg/kg/d PO divided bid

Pediatric

20-30 mg/kg/d PO divided bid

Dosing

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Dosing

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Dosing

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Precautions Barbiturates

These agents are used to induce hepatic enzyme metabolism in order to decrease serum bilirubin levels in some patients with cholestasis in order to improve function.

Phenobarbital (Luminal)

Mainly used as an anticonvulsant, which interferes with transmission of impulses from thalamus to cortex of brain, resulting in imbalance in central inhibitory and facilitatory mechanisms. Used in cholestasis to induce the CYP450 system in treatment of neonatal hyperbilirubinemia and lowering of bilirubin in chronic cholestasis.

Dosing

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Adult

Up to 30 mg/d PO has been described; adjust dose to maintain serum bilirubin levels within target range

Pediatric

5 mg/kg/d PO

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Precautions VitaminsFat-soluble vitamins A, D, E, and K must be administered as individual supplements to assure proper absorption.

Phytonadione (AquaMEPHYTON)

Vitamin K. Fat-soluble vitamin absorbed by the gut and stored in the liver. Necessary for the function of clotting factors in the coagulation cascade. Used to replace essential vitamins not obtained in sufficient quantities in the diet or to further supplement levels.

Dosing

Interactions

Contraindications

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Adult

10 mg PO/IV/IM/SC should replenish the liver stores

Pediatric

1 mg IM

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Vitamin E (Liqui E)

Vitamin E. Prevention and treatment of hemolytic anemia secondary to vitamin deficiency or need for dietary supplementation. Protects polyunsaturated fatty acids in membranes from attack by free radicals and protects RBC against hemolysis.

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Adult

RDA dose: 8-10 mg/d PO (12-15 IU/d)Therapeutic dose: 50-2000 IU/d PODeficiency: 30- to 50-mg tab/cap PO qd(PO dose is usually 4-5 times the RDA)

Pediatric

RDA dose: 3-10 mg/d POTherapeutic dose: 1-100 mg/kg/d PO

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Vitamin A (Aquasol A)

Needed for bone development, growth, visual adaptation to darkness, testicular and ovarian function, and as a cofactor in many biochemical processes.

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Adult

Dietary supplement: 4000-5000 IU/d PORDA: 2670 IU/d (females) and 3330 IU/d (males)

Pediatric

Dietary supplement:<6 months: 1500 IU/d PO6 months to 3 years: 1500-2000 IU/d PO4-6 years: 2500 IU/d PO7-10 years: 3300-3500 IU/d PO>10 years: Administer as in adultsDeficiency:<1 year: 10,000 IU/kg/d IM for 5 d, then 7,500-15,000 IU/d for 10 d1-8 years: 5,000-10,000 IU/kg/d IM for 5 d, then 17,000-35,000 IU/d for 10 d>8 years: 100,000 IU/d IM for 3 d, then 50,000 IU/d for 14 d

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Ergocalciferol (Drisdol, Calciferol)

Vitamin D. Stimulates absorption of calcium and phosphate from small intestine and promotes release of calcium from bone into blood. PO solution comes as 8000 U/mL (200 mcg/mL, 40 U/mcg).

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Adult

10,000-80,000 U/d PO plus 1-2 g/d PO elemental phosphorus

Pediatric

Infants and healthy children: 10 mcg/d PO (400 U)Vitamin D–dependent rickets: 75-125 mcg/d PO (3000-5000 U); not to exceed 1500 mcg/dNutritional rickets and osteomalacia: 25-125 mcg/d PO (1000-5000 U) in normal absorption; 250-650 mcg/d PO (10,000-25,000 U/d) in malabsorption

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Precautions Opioid antagonistsThese agents are used to alleviate pruritus caused by cholestasis. They block opioid-mediated pathways of afferent nerves, which may be producing the itching sensation.

Naltrexone (ReVia)

Cyclopropyl derivative of oxymorphone that acts as a competitive antagonist at opioid receptors. Do not administer this medication until the patient is opioid-free for 7-10 d. Available as 50-mg tab.

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Adult

Initial dose: 25 mg PO; if no withdrawal signs within 1 h, administer another 25 mgMaintenance dose: 50-150 mg 3 times/wk

Pediatric

10 mg/d PO increasing over 3-4 wk; not to exceed 25-30 mg/d

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Precautions Bile salt resinsBile acid–binding resins form a nonabsorbable complex with bile acids in the intestine, which inhibits enterohepatic reuptake of intestinal bile salts and thereby increases the fecal losses of bile salt–bound low-density lipoprotein cholesterol.

Cholestyramine (Questran, Prevalite)

May use as adjunct in primary hypercholesterolemia. Forms a nonabsorbable complex with bile acids in the intestine, which, in turn, inhibits enterohepatic reuptake of intestinal bile salts. Dose based on resin content.

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Adult

4 g PO qd/bid; not to exceed 24 g/d or 6 doses/d; mix with water or juice and drink immediately

Pediatric

240 mg/kg/d PO divided tid; mix with water or juice and drink immediately

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Precautions AntibioticsAntitubercular agents induce liver enzymes and ameliorate pruritus secondary to cholestasis.

Rifampin (Rimactane, Rifadin)

Inhibits RNA synthesis in bacteria by binding to beta subunit of DNA-dependent RNA polymerase, which, in turn, blocks RNA transcription.

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Adult

600 mg PO/IV qd

Pediatric

10-20 mg/kg/d PO/IV; not to exceed 600 mg/d

Follow-up

Further Inpatient Care Follow-up care in patients with cholestasis is disease specific; therefore, refer to articles about

disease states (see Causes).

Patient Education For excellent patient education resources, see eMedicine's Liver, Gallbladder, and Pancreas

Center, Cholesterol Center, and Ear, Nose, and Throat Center. Also, visit eMedicine's patient education articles Gallstones and Nosebleeds.

Miscellaneous

Medicolegal Pitfalls Cholestasis is not a disease but a symptom of a disease; therefore, it is a signal or marker that

disease exists. Cholestasis is never normal and should at all times be investigated for the underlying etiology.

Failure to investigate the cause of a patient's cholestasis may lead to the neglect of a progressive and significant disease process that will cause the patient harm.

Ignoring cholestasis or watching it progress without an understanding of the cause may be considered malpractice if avoidable harm to the patient occurs as a result.

Special Concerns Malnutrition is common in infants and children with chronic liver disease. Its etiology is

multifactorial but is generally due to decreased dietary intake, impaired digestion and absorption, and increased energy expenditure.

Children and especially infants need to be periodically assessed for malnutrition and for vitamin deficiencies because it contributes to a poorer outcome when liver transplantation is considered.