Parathyroids

PARATHYROIDSPARATHYROIDS

Anatomy

PhysiologyPhysiology

Secretes parathyroid hormone (PTH)

PTH produced by the chief cells PTH secretion is controlled by a complex

feed back mechanism dependent on serum Ca levels

PTH or its fragments can be measured by radio immunoassay

Actions of PTHActions of PTH

Stimulation of osteoclastic activity bone resorption and mobilization of Ca &Phosphate

Absorption Ca from the gut Reduces the urinary Ca by increasing

the reabsorption Ca by renal tubules Reduces the renal tubular absorption of

PO4 Phosphaturia

CalcitoninCalcitonin

Secreted by C cells of thyroidOpposite action of PTH Serum CaCa storage in the bones

HYPERPARATHYROIDISMHYPERPARATHYROIDISM

Secretion of PTHOne of the most common causes of

hypercalcaemiaLarge no. of patients are asymptomaticIn India a high proportion of patients

presents with skeletal and renal disease

ClassificationClassification

Primary Hyperparathyroidism(PHPT) – inappropriately secretion of PTH

Secondary hyper parathyroidism – chronic hypocalcaemia reactive hyperplasia of all four glands

Tertiary hyper parathyroidism – reactive hyperplasia, the glands become autonomous e.g, chronic renal failure pt. After transplantation

PathologyPathology

Parathyroid adenomaUsually single,5% multipleWhole gland is enlarged, darker in color

more vascular than usualA rim of compressed normal tissues seen

surrounding the adenomaPredominance of chief or clear cells

Pathology(contd.)Pathology(contd.)

Parathyroid hyperplasia – hyperplasia of all the glands

Parathyroid carcinoma – rare (<1%) – palpable swelling , very large swelling infiltrating to the thyroid or adjacent structures – distant metastasis & recurrence have been reported

Multiple Endocrine Multiple Endocrine Neoplasia (MEN) SyndromeNeoplasia (MEN) Syndrome

Autosomal dominant disorderAPUD cells are involvedMEN Type I (Werner syndrome)

Hyperparathyroidism,pancreatic islet cell tumors,pituitary tumor

MEN Type IIMEN Type II

MEN Type IIA(Sipple syndrome)

MedullaryCa.thyroid,Phaeochromacytoma,Hyperparathyroidism

MEN TypeIIB(MEN TypeIII)

Medullary Ca ,Phaechromocytoma ,and mucosal neuromas

Clinical presentation Clinical presentation (contd.)(contd.)

Skeletal - mild to crippling bone disease

Osteitis fibrosa cystica, Brown tumors , single or multiple bone cysts, pseudomotor & pathological fractures . Vague pain in the bone and joints

Renal stones, nephrocalcinosis

Clinical PresentationClinical Presentation

Age 20 – 45Females :Males = 2:1Most common presentation in the

western world Asymptomatic hypercalcemia

Classical manifestations in the 3rd world ,viz. “Bones,stones,abdominal groans & psychic moans”

Clinical presentation Clinical presentation (contd.)(contd.)

Gastro intestinal - nausea, vomiting,anorexia and weight loss, peptic ulceration, pancreatitis.

Nervous system – lethargy, listlessness,personality changes,irrational behavour and memory loss. Hyper calcemia depression of nervous system coma

Laboratory findingsLaboratory findings

Serum Ca - most common finding PHPT. Normocalcemic PHPT not uncommon in India. Serum Ca level to be corrected with respect to serum albumin

Urinary Ca –24 hrs Serum alk. Phosphatase in bone diseaseSerum PTH – Normal – 65 pg/ml

Clinical presentation Clinical presentation (contd.)(contd.)

Other complications: Corneal calcification ,Itching

Hypertension is seen in many pts. Reason not clear

Common causes of Common causes of hypercalcemiahypercalcemia

a.Bony metastasis – breast, bronchus, prostate,kidney, thyroid

b.PTH secreting solid tumorsc.Haematological malignancies –multiple

myelomad.Vit D intoxicatione.Sarcoidosisf.Immobilisation,medications like lithium,

thiazide etc

Imaging investigationsImaging investigations

Radiology Useful for skeletal lesionsUltrasound Adenoma or multiple

enlarged glands may be detectedCT Scan Lesions in the chestThallium Technetium subtraction scan99 Tc Sestambi scanSelective angiography & venous sampling

TreatmentTreatment

Surgery is the treatment of choice

Parathyroid adenoma Excision of the adenoma

Parathyroid hyperplasia If more than one gland is involved,3 ½ gland can be removed or total parathyroidectomy with auto transplantation

Parathyroid Ca Hemithyroidectomy + involved gland