EXAM #1: PATHOLOGY OF THE PARATHYROID Flashcards
What is the most common cause of primary hyperparathyroidism?
Parathyroid adenoma
How is the production of PTH described in a parathyroid adenoma?
Autonomous overproduction of PTH
What is the net effect of of overproduced PTH?
Hypercalcemia
How does overproduction of PTH cause hypercalcemia?
1) Increased bone resorption of Ca++
2) Increased renal tubular reabsorption of Ca++
3) Increased urinary EXCRETION of phosphate*
4) Increased synthesis of Vitamin D
PTH= Phosphate Trashing Hormone
What is the typical urine Ca++ finding in primary hyperparathyroidism?
Hypercalciuria
What is the sequelae of hypercalciuria in primary hyperparathyroidism?
Renal stones causing:
- Flank pain
- Hematuria
What are the major clinical manifestations of primary hyperparathyroidism?
1) Stones
2) Bones= osteomalacia (softening of the bones) then pathologic fracture/ “brown tumor”
3) Groans= gastritis/ gallstones
4) Moans= psych
What is another name for a Brown Tumor?
Osteitis fibrosa cystica
Why does primary hyperparathyroid cause abdominal pain?
- Hypercalcemia stimulates gastrin release and acid secretion
- Results in PUD
Grossly, is a parathyroid adenoma singular or multinodular? How big are these tumors?
Singular and between 0.5-5 grams
*Note that this is opposite of hyperplasia, where all four glands are bigger
What patient population is a parathyroid adenoma most common in?
Older women
What is the name of the surgical procedure to remove a parathyroid adenoma?
MIRP, Minimally-Invasive Radioguided Parathyroidectomy
*Utilizes Tc99 sestamibi
Describe the histologic appearance of parathyroid adenoma.
- Dominance of chief cells with no fat/stromal cells
- Outlined by a thin rim of normal parathyroid
What is the second most common cause of primary hyperparathyroidism?
Parathyroid hyperplasia
How does parathyroid hyperplasia differ from a parathyroid adenoma?
All four glands are big
What does MEN stand for? What are the MEN syndromes?
Multiple Endocrine Neoplasia
*This is parathyroid disease with tumors of other endocrine organs
Histologically, what is the difference between a parathyroid adenoma and hyperplasia?
- There is NO RIM OF NORMAL tissue in parathyroid hyperplasia
- Like adenoma, no fat cells as well
What is secondary hyperparathyroidism?
Parathyroid hyperplasia due to HYPOCALCEMIA from other causes
What is the most common cause of secondary hyperparathyroidism?
Chronic Renal Failure (CRF)
Why does CRF cause hypocalcemia?
- Abnormal renal loss of Ca
- Decreased renal conversion to 1,25(OH) 2 D
What thyroid cancer is associated with secondary hyperparathyroidism?
Medullary carcinoma of the thyroid
What oncogene mutation is associated with Medullary Carcinoma of the Thyroid?
RET
What drug is indicated for patients with secondary parathyroidism due to renal pathology?
Calcitriol–the active metabolite of Vitamin D
What is the surgical procedure to treat parathyroid carcinoma?
En bloc resection
Histologically, what is the most common finding in parathyroid carcinoma?
Thick fibrous bands
Grossly, how does a parathyroid carcinoma appear?
Gray-white irregular mass
*Note that this is over 10 grams
List three common causes of hypoparathyroidism?
1) Iatrogenic during thyroidectomy
2) Autoimmune disorder
3) DiGeorge Syndrome
What are the symptoms of hypoparathyroidism?
1) Mental status changes
2) Paresthesias
3) Chovstek sign
4) Trousseau sign
5) Convulsions
6) Tetany
What are two clinical manifestations of tetany?
- Risus sardonicus
- Opisthotonus
What labs confirm the diagnosis of hypoparathyroidism?
- Decreased Ca++
- Increased Phosphate
What is the treatment for hypoparathyroidism?
1) Vitamin D
2) Calcium gluconate*
3) Recombinant human PTH
*Reduces the excitability of cardiac myocytes and is thus cardioprotective in hyperkalemia
