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Fiser's ABSITE Ryan > Chapter 23 - Parathyroid > Flashcards

Chapter 23 - Parathyroid Flashcards

1
Q

Superior parathyroids derived from what?

A

4th pharyngeal pouch

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2
Q

Inferior parathyroids derived from what?

A

3rd pharyngeal pouch

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3
Q

Relation of superior parathyroids to surrounding structures?

A

Lateral to RLNs, posterior surface of superior portion of thyroid, above inferior thyroid artery

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4
Q

Relation of inferior parathyroids to surrounding structures?

A

Medial to RLNs, more anterior, below inferior thyroid artery

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5
Q

Most common ectopic location of inferior parathyroids?

A

Tail of the thymus; can migrate to the anterior mediastinum

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6
Q

Other ectopic sites of parathyroids?

A

Intrathyroid, mediastinal, near TE groove

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7
Q

What % of patients have all 4 glands?

A

90%

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8
Q

Blood supply to both superior and inferior parathyroids?

A

Inferior thyroid artery from thyrocervical trunk

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9
Q

Effects of PTH?

A

Increase serum Ca; increase kidney Ca reabsorpiton in distal convoluted tubule, decrease kidney PO4 absorption, increase osteoclasts in bone to release Ca and PO4, increase Vit D production in kidney

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10
Q

How does vitamin D increase Ca?

A

Increases intestinal Ca and PO4 absorption by increasing Ca-binding protein

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11
Q

Effects of calcitonin?

A

Decrease serum Ca; decrease bone Ca resorption (osteoclast inhibition), increase urinary Ca and PO4 excretion

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12
Q

Normal PTH level?

A

5-40 pg/mL

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13
Q

Most common cause of hypoparathyroidism?

A

Previous thyroid surgery

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14
Q

What oncogene increases the risk for parathyroid adenomas?

A

PRAD-1

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15
Q

What causes primary hyperparathyroidism?

A

Autonomously high PTH

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16
Q

How is the diagnosis of primary hyperparathyroidism made?

A

Increased Ca, decreased phos; Cl- to phos ratio >33, increased renal cAMP, HCO3- secreted in urine

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17
Q

Acid-base disorder seen with primary hyperparathyroidism?

A

Hyperchloremic metabolic acidosis

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18
Q

What is the bone lesion characteristic of primary hyperparathyroidism?

A

Osteitis fibrosa cystica (brown tumors)

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19
Q

Symptoms of primary hyperparathyroidism?

A

Muscle weakness, myalgia, nephrolithiasis, pancreatitis, PUD, depression, bone pain pathologic fractures, mental status changes, constipation, nausea and vomiting, anorexia

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20
Q

Indications for surgery for primary hyperparathyroidism?

A

Ca >13, decreased Cr clearance, kidney stones, substantially decreased bone mass

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21
Q

% of patients with single adenoma?

A

80%

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22
Q

% of patients with multiple adenomas?

A

4%

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23
Q

% of patients with diffuse hyperplasia?

A

15%; pts with MEN I or IIa have 4-gland hyperplasia

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24
Q

Treatment for parathyroid adenoma?

A

Resection; inspect other glands to r/o hyperplasia or multiple adenomas

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25
Q

Treatment for parathyroid hyperplasia?

A

Do not biopsy all glands (risk hemorrhage); resect 3.5 glands or total parathyroidecomy and autoimplantation

26
Q

Treatment for parathyroid adenocarcinoma?

A

Radical parathyroidectomy (with ipsilateral thyroid)

27
Q

Ideal time for operation in pregnant patient?

A

2nd trimester; increased risk of stillbirth if not resected

28
Q

Why draw intra-op PTH levels?

A

Helps determine if causative gland is removed; PTH should go to <1/2 the preop value

29
Q

What is the half-life of PTH?

A

3-4 minutes

30
Q

What is the most common location of a gland that was unable to be found on initial operation?

A

Normal anatomic position

31
Q

What is postop hypocalcemia caused by following parathyroidectomy?

A

Bone hunger, hypomagnesemia, failure of parathyroid remnant or graf

32
Q

What is the most common cause of persistent hyperparathyroidism?

A

1%; due to missed adenoma

33
Q

What causes recurrent hyperparathyroidsim?

A

New adenoma formation, tumor implants that have grown, recurrent parathyroid carcinoma

34
Q

Bone hunger will show what lab values?

A

Normal PTH, decreased HCO3-

35
Q

Aparathyroidism will show what lab values?

A

Decreased PTH, normal HCO3-

36
Q

What is sestamibi-technetium-99 good for?

A

Preferential uptake by overactive parathyroid gland; good for picking up adenomas (not for hyperplasia); best for trying to pick up ectopic glands

37
Q

What patients show secondary hyperparathyroidism?

A

Renal failure

38
Q

Lab values in secondary hyperparathyroidism?

A

Increased PTH in response to decreased Ca

39
Q

Treatment for secondary hyperparathyroidism?

A

Control diet PO4, PO4-binding gel, decreased aluminum, Ca supplement, vitamin D/Ca in dialysate

40
Q

When is surgery indicated for secondary hyperparathyroidism?

A

Bone pain (80-90% get relief); total parathyroidecomy with autotransplantation

41
Q

What is tertiary hyperparathyroidism?

A

Renal disease has been corrected with transplant, but still oerproduces PTH

42
Q

Treatment of tertiary hyperparathyroidism?

A

Subtotal or total parathyroidectomy with autoimplantation

43
Q

Lab values seen in familial hypercalcemic hypocalciuria?

A

High serum Ca, low urin Ca (should be high if hyperparathyroidism)

44
Q

What is the cause of familial hypercalcemic hypocalciuria?

A

Defect in PTH receptor in distal convoluted tubule of kidney; causes increased resorption of Ca

45
Q

Treatment for familial hypercalcemia hypocalciuria?

A

Nothing. Ca generally not that high; NO parathyroidectomy

46
Q

What is pseudohypoparathyroidism caused be?

A

Defect in PTH receptor in kidney, does not respond to PTH

47
Q

5-year survival for parathyroid cancer?

A

50% 5 year survival

48
Q

Lab values in parathyroid cancer?

A

High Ca, PTH, and alkaline phosphatase

49
Q

Most common site of mets from parathyroid cancer?

A

Lung

50
Q

% of patients with parathyroid cancer recurrence?

A

50%

51
Q

What are the tumors of MEN syndromes derived from?

A

APUD cells

52
Q

Inheritance of MEN syndromes?

A

Autosomal dominant, 100% penetrance, variable expressivity

53
Q

Tumors associated with MEN I?

A

Parathyroid hyperplasia (usually 1st to become symptomatic), pancreatic islet cell tumors, pituitary adenoma; correct hyperparathyroidism 1st

54
Q

Tumors associated with MEN IIa?

A

Parathyroid hyperplasia, pheochromocytoma, medullary cancer of thyroid; correct pheo first

55
Q

1 cause of death in MEN IIa/IIb?

A

Medullary thyroid cancer

56
Q

Tumors associated with MEN IIb?

A

Pheochromocytoma, medullary cancer of thyroid, mucosal neuromas, Marfan’s habitus, musculoskeletal abnormalities

57
Q

Gene mutation associated with MEN I?

A

MENIN gene

58
Q

Gene mutation associated with MEN II?

A

RET proto-oncogene

59
Q

Other causes of hypercalcemia?

A

Malignancy, hyperthyroidism, immobilization, granulomatous disease, excess vitamin D, milk-alkali syndrome, thiazide diuretics

60
Q

MOA of midramycin?

A

Inhibits osteoclasts (used with malignancies or failure of conventional treatment); has hematologic, liver, renal side effects

61
Q

What causes a hypercalcemic crisis? Treatment?

A

Usually secondary to another surgery; furosemide, dialysis

Fiser's ABSITE Ryan (50 decks)

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