8/9/2019 USMLE step 1 important points http://slidepdf.com/reader/full/usmle-step-1-important-points 1/33 USMLE STEP-1 POINTS MADE EASY 2000 + Important exclusive points Mostly repeated in USMLE part 1 Made easy to understand Note :there are many things like this that we have at our institute and we distribute all this for our students so ill be posting some of sample points which is quite enough to understand about our material www.gims-org.com
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(causing increased pigmentation), and liver (causing cirrhosis). Treatment
consists of regular phlebotomy and deferoxamine, an iron chelator.
Wilson's disease This autosomal recessive disorder is caused by impaired copper excretion. Signs and
symptoms include tremor, ataxia, dementia, and psychoses. The classic
ophthalmic finding is Kayser-Fleischer rings (brown-pigmented rings at the edge
of the cornea) from copper deposits. Treat with penicillamine, a copper
chelator.
AcetazolamideA
cetazolamide is a carbonic anhydrase inhibitor. Members of this class of drugs aregenerally not used to treat hypertension, as the diuresis is self-limiting within
two to three days. The mechanism of self-limiting diuresis is as follows: By
inhibiting carbonic anhydrase in proximal convoluted tubules, acetazolamide
causes increased urinary excretion of bicarbonate. As the body bicarbonate level
decreases, excretion slows even with continued diuretic use, and the diuresis
Amiloride This potassium-sparing diuretic works in the late distal tubules and the cortical collecting
ducts by inhibiting reabsorption of Na and secretion of K and H. It would be
useful for treatment of hypertension, but it does not have any effect on
reabsorption of calcium. Furosemide is a better option, as it would also helpreabsorb calcium and, therefore, not make the patient's osteoporosis worse.
Clorothiazide This thiazide diuretic inhibits Na/CL cotransported in the early distal convoluted
tubules. It is useful for treatment of hypertension, especially in a patient with
osteoporosis, as it increases calcium reabsorption from urine by an unknown
mechanism.
Furosemide Furosemide is a loop diuretic that works on the medullary ascending loop of Henle by
inhibiting Na/K/2 CL cotransport that accounts for 20% to 25% of reabsorption
of Na. Downstream sites cannot compensate for the sodium excretion, which
makes these drugs very efficacious and useful for treatment of hypertension.
Loop diuretics cause decreased reabsorption of calcium from urine, however,
and they may worsen this patient's osteoporosis condition. In fact, loop
diuretics are often employed for treatment of hypercalcemia (as induced by
malignancy, for example).
Mannitol Mannitol is an osmotic diuretic. Most of the filtered solutes will be excreted in larger
amounts unless they are actively reabsorbed. Osmotic diuretics are not
indicated for treatment of hypertension, but may be used to decrease cerebral
edema and intraocular pressure.
Cavernous sinus This sinus contains cranial nerves III, IV, V, and VI as well as the internal carotid
artery. Cranial nerves VII and VIII do not pass through here.
Floor of the middle cranial fossa in the trigeminal dural cave The middle cranial fossa contains anumber of structures that carry many important vessels and nerves, including
the cranial nerves associated with ocular motility (III, IV, and VI) and sensation
(V). However, this portion of the fossa does not contain any nerves that would
Internal auditory meatus This structure holds the facial and vestibulocochlear nerves (cranial nerves
VII and VIII) as well as the labyrinthine artery. Because the patient has difficulty
with the facial muscles of both the upper and lower face, we know that the
lesion in cranial nerve VII must be peripheral instead of central (in which only
the lower portion would be involved). Cranial nerve VII also gives rise to the
preganglionic parasympathetic fibers that will innervate the lacrimal gland,
which forms tears. A lesion in cranial nerve VIII in this location also explains
unilateral hearing loss.
Jugular foramen This foramen transmits cranial nerves IX, X, and XI as well as a portion of the internal
jugular artery. These structures are not responsible for the patient's symptoms.
Superior orbital fissure This fissure transmits cranial nerves associated with ocular motility (cranialnerves III, IV, and VI) as well as the ophthalmic nerves and veins. A lesion here
would not explain the patient's auditory symptoms or the lack of abnormalities
in ocular motility.
Leukotrienes productionAspirin, like NSAIDs and acetaminophen, blocks COX-1 and COX-2 enzymes
in the arachidonic acid metabolism. However, the lipoxygenase enzyme
pathway is not blocked, thus funneling most of the arachidonic acid through the
lipoxygenase pathway that produces leukotrienes (LTB, LTC, LTD). LTs are
responsible for increased bronchial tone (i.e., bronchospasm), causing the
respiratory distress symptoms observed in this patient.
Phospholipase A2 deficiency A deficiency in phospholipase A2 would mean that no arachidonic acid is
produced. If there is a deficiency in arachidonic acid, then aspirin has no
negative effect and would not cause respiratory distress.
Prostacyclin production Prostacyclins are by-products of arachidonic acid metabolism via the COXenzyme pathway. Because aspirin blocks both COX-1 and COX-2, no PGIs will be
produced. In addition, PGIs are responsible for decreased bronchial and vascular
diarrhea, which later consists of blood and mucus. No rash is associated with
shigellosis. Lactose is not fermented, as evidenced by colorless colonies on
MacConkey agar.
Colored (pink) colonies on MacConkey agar; urease positive K lebsiella is found in the large intestine,
soil sources, and water sources. The thick capsule is characteristic of this
bacterium. K lebsiella causes pneumonia in the elderly, diabetic patients,
patients with chronic obstructive pulmonary disease, and alcoholics. Pink
coloration on MacConkey plates indicates lactose fermentation. Current jelly
sputum, necrosis, and abscess formation are commonly associated with
pneumonia caused by K lebsiella.
Colored (pink) colonies on MacConkey agar; metallic green sheen on EMB agar E sc heric hia coli causesdiarrhea, urinary tract infections, hemolyticuremic syndrome, and meningitis.
Pink coloration on MacConkey plates indicates lactose fermentation.
A great increase cardiac output and GFR Prazosin does not greatly affect cardiac output, renal
perfusion. or GFR; rather, its action is to decrease arterial and venous resistance.
There is some effect but it is not a dramatic one
A high risk for syncope Syncope often is a side effect of alpha inhibitors. It is often associated with the
first dose, but prazosin is usually given at night to prevent this side effect.
Increased tone in the smooth muscle of the bladder and prostate, leading to decreased urinary
retention The tone in the prostate gland is decreased, which leads to the
decrease in urinary retention.
An association with bradycardia Alpha blockers are associated with tachycardia. Beta blockers
decrease the sympathetic tone on the heart, thereby reducing chrontopic
stimulation to the heart. The alpha blockers affect only the resistance of the
blood circuit, so in response to a relatively low blood pressure the sympathetic
nervous system stimulates the heart to beat faster and harder.
Hypertensive emergencyThis condition is typically seen in patients who have end-organ damage,
such as retinal changes, mental status changes, or renal dysfunction. It does not
specifically present with a picture typical for pneumonia.
Plague The plague (Y ersinia pestis infection) typically presents with tachycardia, tender lymph nodes
(particularly inguinal), high fever, malaise, and myalgia. It can also be associated
with a lobar process on CXR.
Pulmonary tuberculosis While the malnourishment fits this diagnosis, the severe hypoxia is more
indicative of PCP.
Chloroquine One would not use chloroquine against chloroquine-resistant species of Plasmodia.
Iodoquinol This luminal amebicide may be used against E ntameba histolytica, but not against any
species of Plasmodia.
Mefloquine Mefloquine is used for prophylaxis in cases where a patient is predicted to be exposed to
chloroquine-resistant P. falcipartum, as in this case. A blood schizonticide, it has
no effect on extraerythrocytic stages of the malarial parasite. Therefore,mefloquine does not act against P. ovale or P. vivax , which left this patient
vulnerable to malaria caused by infection with one of these species.
Pentamidine This drug is used for trypanosomiasis and in Pneumocystis carinii pneumonia, but not
against malaria.
Primaquine Primaquine is used for prophylaxis in cases where a patient is predicted to be exposed to
P. ovale or P. vivax . This patient was treated with a drug that would decrease
her chances of getting malaria via P. falcipartum. Primaquine is a tissue
schizonticide that works by forming cellular oxidants.
A patient is confides in you her plan for killing another person A person with a plan to harm another
person needs to be taken seriously. If there is no other way to warn the person
at risk, it is the obligation of anyone who knows of this plan to break
confidentiality.
A husband calls your office for his wife's test results without having her explicit permission to give outany information This scenario does not meet the requirements for breach of
confidentiality.
A parent asks you whether her teenage daughter has been taking birth control pills In most states,
teenagers are granted confidentiality from their parents regarding sexual
matters.
The local TV station contacts the emergency room to verify whether a celebrity has been recently
treated All patients, including celebrities, have the right to privacy and not to
have their presence confirmed or denied unless they authorize it.
Lysosomal storage Diseases such as Gaucher disease do not give the clinical findings described here.
An alpha-1,6-glucosidase deficiency In Cori's disease, patients lack a debranching enzyme.
A glucose-6-phosphatase deficiency In Von Gierke's disease, patients exhibit severe fasting
hypoglycemia and have increased amounts of liver glycogen.
A glycogen phosphorylase enzyme deficiency In McArdle's disease, patients exhibit cramps and
weakness after minimal exertion.
A lysosomal glucosidase deficiency In Pompe's disease, patients often die within the first year because
of a defective pump.
Which of the following hormones is responsible for stimulating pancreatic enzyme secretion,
stimulating gallbladder contraction, and inhibiting gastric acid secretion?
Increased anti-p24 antigen Anti-p24 antigen does not appear until 6 weeks after infection and peaks
Normal CD4 count and increased p24 antigen One month after infection with
HIV, patients will have decreased levels of CD4 lymphocytes; this level
eventually increases two to three months after infection. around 812 weekspost-infection
Normal CD4 count and increased p24 antigen One month after infection with HIV, patients will have
decreased levels of CD4 lymphocytes; this level eventually increases two to
three months after infection. One month after infection, p24 antigen levels peak
and then decrease by two months post-infection.
Normal CD4 count and undetectable p24 antigen One month after infection with HIV, patients will
have decreased levels of CD4 lymphocytes; this level eventually increases two to
three months after infection. One month after infection, p24 antigen levels peak
and then decrease by two months post-infection.
The husband suffers from a kinesin deficiency The deficiency is in the dynein protein
The patient suffers from Kartagener's syndrome The constellation of infertility,
bronchiectasis/sinusitis, and situs inversus should make you think of
Kartagener's syndrome. These patients suffer from a deficiency of the dynein
protein found in cilia that is responsible for ciliary motion. In the absence of thiscritical protein, males are infertile secondary to sperm immobility. The lack of
proper ciliary motility also means decreased bacterial clearance from the lungs
and sinuses, resulting in bronchiectasis and chronic sinusitis. The situs inversus is
secondary to improper cell mobility during embryogenesis.
Flutamide The patient has metastatic carcinoma of the prostrate. He has a history of BPH, which is
common in men older than 50 years of age. Superimposed on the BPH the
patient has developed prostate cancer that has now metastasized to his spine
not an uncommon mode of presentation for prostate cancer. Flutamide is an
oral anti-androgen at the level of the prostate gland and prostate cancer cells. It
blocks the stimulation signal for proliferation in these cells and controls the rate
The patient should be taught how to self-catherize, because he will never be able to control his
bladder. Self-catherization is appropriate if the patient can never control his
bladder. This permanent condition can be caused by loss of sensory nerves.
Codeine This drug is a narcotic. Narcotics have an addictive potential.
Heroin This drug is a narcotic. Narcotics have an addictive potential.
Hydrocodone This drug is a narcotic. Narcotics have an addictive potential.
Morphine This drug is a narcotic. Narcotics have an addictive potential.
Tramadol This agent is the only non-narcotic drug on the list. A patient with a history of substance
abuse (no matter what the substance of abuse was) must not be given
medications that have the potential to be addicting and abused. The diagnosis
of substance abuse is a lifetime diagnosis. Patients so diagnosed, even if their
addiction resolves, continue to maintain that diagnosis for life.
A 25-year-old female has recently had her first psychotic break. After many months of therapy, she has
been diagnosed with paranoid schizophrenia. She has been responding well to her
inpatient olanzapine regimen, and you would like to continue this medication with
her while following her in the outpatient setting. Which of the following features
of her family history would be of the greatest concern to you?
Three first-degree relatives with type II diabetes mellitusThere is an established genetic component to
type II diabetes mellitus. Olanzapine has been shown to cause significant
increases in weight, which in turn promotes a state of hyperinsulinemia and
insulin resistance. It would be worrisome to start a patient with a significant
family history of diabetes mellitus on a medication that would further increase
her risk of developing this disease via weight gain and insulin resistance.
A 65-year-old woman comes into your office complaining of a left-sided headache, jaw pain, and stiff,
achy shoulders for about one week. She has no other medical problems and has
never had a headache before this presentation. On examination, she has a
prominent, pulsating left temporal artery that is very tender to palpation. Yoususpect temporal arteritis (giant-cell arteritis) and decide to do a biopsy to
confirm the diagnosis. What is the best course of action in the meantime, while
waiting for the results?
High-dose prednisone A serious consequence of untreated temporal arteritis is blindness due to
inflammation extending to the optic nerve. If your clinical suspicion is high, it is
best to start steroids immediately. If the biopsy is negative for temporal
arteritis, the short course of steroids is unlikely to have any adverse effects.
Tylenol for headache relief Although Tylenol can help relieve pain symptoms and could be given as an
adjuvant to treatment, it is also important to start the patient on steroids.
Nothing; wait for results before giving any treatment Any delay in treatment while waiting for the
results increases the patient's risk of blindness.
Antibiotics Temporal arteritis is not an infectious process, but rather is caused by chronic
inflammation of large blood vessels. Antibiotics would not help reduce the
inflammation.
Have other family members come in for evaluation Temporal arteritis is not a hereditary process.
However, its incidence increases with advancing age. If family members present
with similar complaints, it is best to have them evaluated.
During a busy day in the emergency room, a 37-year-old male presents complaining of acute epigastric
abdominal pain, describing it as shooting straight through to my back. He alsostates that he has not been able to eat because of nausea and vomiting. On
examination, the patient is afebrile and uncomfortable, and he requests
medication for his pain. He appears intoxicated. The abdominal exam reveals mild
distention, absent bowel sounds, and extreme pain on palpation, but no rebound
tenderness. Initial lab results show elevated amylase and lipase levels. A KUB
shows multiple calcifications in the abdomen. Which diagnosis best explains these
results?
Pancreatitis In the setting of alcohol use, this patient's presentation is convincing for acute
pancreatitis in the context of chronic pancreatitis.A
lcohol use and gallstones arethe main causes of acute pancreatitis in the United States; the presence of
pancreatic calcifications suggests that the patient has experienced previous
episodes.A follow-up CT scan or ultrasound may reveal pancreatic fluid
collections, indicating the development of a pseudocyst.
A 25-year-old woman with regular menses is given an estrogen challenge. The challenge consists of
exogenous estrogen supplementation to see if her LH level will increase. Which of
the following regimens would be most effective?
Estrogen 10 days after menses High levels of estrogen are needed to stimulate adequate LH
production.
Estradiol 20 days after menses If estradiol was given 20 days after menses, then the cycle would
already be in the luteal phase. Once in the luteal phase, the LH level will not rise
until the next cycle.
Progesterone 10 days after onset of menses Progesterone level is typically very low during the
follicular phase. This hormone does not stimulate LH production.
Progesterone 20 days after onset of menses Progesterone does not stimulate LH production.
Synthetic FSH 15 days after onset of menses FSH is the not the principal stimulator of LH production.
A 47-year-old African American male presents for follow-up for depression. He denies improvement
after eight weeks of sertraline with good compliance. His smoking has increased
to three packs per day, up from two packs per day for 30 years. He admits tointermittent back pain, incapacitating pruritus, and a 30-pound weight loss.
Umbilical tenderness and a distended gallbladder are noted on physical
examination. Which of the following is the most likely to be true in this case?
The pancreatic head is the origination site of the patient's pancreatic carcinoma. Pancreatic carcinoma
most often occurs in the pancreatic head. This location allows earlier
identification as compared to the tail of the pancreas. However, surgical
procedures require removal of the pancreatic head, gallbladder, and a portion of
the duodenum (Whipple procedure). Migrating thrombophlebitis is often
observed with pancreatic carcinoma.
No association has been made between cigarette smoking and pancreatic carcinoma. Smoking