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Fiser ABSITE Review + Decker + TrueLearn > 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 than superior PT
  • Below inferior thyroid artery
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5
Q

Most common ectopic location of inferior parathyroids?

Other locations?

A

Tail of the thymus.

Intrathyroid, mediastinal (anterior), near TE groove.

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6
Q

What % of patients have all 4 parathyroid glands?

A

90%

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7
Q

Blood supply to both superior and inferior parathyroids?

A

Inferior thyroid artery from thyrocervical trunk

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8
Q

Effects of PTH?

A

Increase serum Ca and decrease serum PO4 through kidneys and bones

  • Increase kidney Ca reabsorpiton in DCT
  • Decrease kidney PO4 absorption
  • Increase Vit D production in kidney
  • Increase osteoclasts: release Ca and PO4
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9
Q

How does vitamin D increase Ca?

A

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

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10
Q

Effects of calcitonin?

A

Antagonistic to PTH - Decreases serum Ca

  • Decrease bone Ca resorption (osteoclast inhibition)
  • Increase urinary Ca and PO4 excretion
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11
Q

Normal PTH level?

A

5-40 pg/mL

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12
Q

Most common cause of hypoparathyroidism?

A

Previous thyroid surgery

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13
Q

What oncogene increases the risk for parathyroid adenomas?

A

PRAD-1

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14
Q

What causes primary hyperparathyroidism?

A

Autonomously high PTH

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15
Q

How is the diagnosis of primary hyperparathyroidism made?

A
  • Increased Ca
  • Decreased PO4
  • Cl- to phos ratio >33
  • Increased renal cAMP
  • HCO3- secreted in urine
  • Causes hyperchloremic metabolic acidosis
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16
Q

Acid-base disorder seen with primary hyperparathyroidism?

A

Hyperchloremic metabolic acidosis

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17
Q

What is the bone lesion characteristic of primary hyperparathyroidism?

A

Osteitis fibrosa cystica (brown tumors)

Caused by high turnover

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18
Q

Symptoms of primary hyperparathyroidism?

A

Think of hypercalcemia and hypophosphatemia symptoms

  • Depression and mental status changes
  • Pancreatitis
  • Peptic ulcer disease
  • Constipation, nausea/vomiting, anorexia
  • Nephrolithiasis
  • Muscle weakness and myalgia
  • Bone pain and pathologic fractures
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19
Q

Indications for surgery for primary hyperparathyroidism?

A
  • Ca >13 (psx w/ bone pain, AMS, GI sx)
  • Decreased Cr clearance (increasing Cr on BMP), CrCL <60 ml/min
  • 24 hr urinary Ca >400 (rules out FHH)
  • Kidney stones (flank pain and XR findings)
  • Silent nephrocalcinosis (imaging)
  • Substantially decreased bone mass - osteoporosis (BMD test < -1 is osteopenia, < -2.5 is osteoporosis)
  • Pathologic fracture
  • Dx at age <50 yrs
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20
Q

% of patients with single adenoma?

A

80%

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21
Q

% of patients with multiple adenomas?

A

4%

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22
Q

% of patients with diffuse hyperplasia?

A

15%

MEN I or IIa pts have 4-gland hyperplasia

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23
Q

Treatment for parathyroid adenoma?

A

Resection

Inspect other glands to r/o hyperplasia or multiple adenomas

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24
Q

Treatment for parathyroid hyperplasia?

A

Do not biopsy all glands (risk hemorrhage)

Resect 3.5 glands or total parathyroidecomy and autoimplantation

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25
Q

Treatment for parathyroid adenocarcinoma?

A

Radical parathyroidectomy (with ipsilateral thyroid)

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26
Q

Ideal time for operation in pregnant patient for hyperparathyroid disease?

A

2nd trimester

Increased risk of stillbirth if not resected

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27
Q

Why draw intra-op PTH levels?

A

Helps determine if causative gland is removed

PTH should go to <1/2 the preop value

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28
Q

What is the half-life of PTH?

A

3-4 minutes

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29
Q

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

A

Normal anatomic position

Isthmus is MC ectopic location

30
Q

What is postop hypocalcemia caused by following parathyroidectomy?

A
  • Bone hunger (hx of osteitis fibrosa)
  • Hypomagnesemia (diminishes PTH secretion, increases PTH resistance)
  • Failure of parathyroid remnant or graft

Postop parathyroidectomy should have serum Ca levels monitored 2-4x/day, hypoMg corrected, PO Ca and vit D when they can swallow, IV Ca if they develop symptoms, dialysis if symptoms are severe.

31
Q

What is the most common cause of persistent hyperparathyroidism?

A

Missed adenoma - 1%

Usually left in normal anatomic position, isthmus is MC ectopic location

Should have intraop PTH <1/2 of preop

32
Q

What causes recurrent hyperparathyroidsim?

A
  • New adenoma formation
  • Tumor implants that have grown
  • Recurrent parathyroid carcinoma
33
Q

Bone hunger (or hungry bone syndrome) psx, dx, mgmt?

A
  • Path: chronic bone dz (osteitis fibrosa), s/p parathyroidx
  • Psx: tetany, seizures, arrhythmias, laryngeal spasm
  • Dx: dec Ca - severe and prolonged; nl PTH; dec HCO3
  • Tx: Vit D and Ca, fix hypoMg, avoid PO4 (can bind Ca and dec serum levels), IV Ca if symptoms, dialysis if severe
34
Q

Aparathyroidism will show what lab values?

A

Decreased PTH, normal HCO3-

35
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.

36
Q

What patients show secondary hyperparathyroidism?

A

Renal failure. Leads to interferance with vit D metabolism, leading to decreased Ca absorption from GI tract.

Other causes are sprue, chronic vit D deficiency, aluminum toxicity seen in hemodialysis.

Usually will not develop hypercalcemia.

37
Q

Lab values in secondary hyperparathyroidism?

A

Increased PTH in response to decreased Ca.

38
Q

Treatment for secondary hyperparathyroidism?

A

Decrease PO4, supplement the hypocalcemia

  • Control diet PO4
  • PO4-binding gel
  • decreased aluminum
  • Ca supplement
  • vitamin D/Ca in dialysate
39
Q

When is surgery indicated for secondary hyperparathyroidism?

A

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

40
Q

What is tertiary hyperparathyroidism?

A

Renal disease has been corrected with transplant, but still overproduces PTH. Usually after longstanding secondary hyperparathyroidism.

41
Q

Treatment of tertiary hyperparathyroidism?

A

Subtotal or total parathyroidectomy with autoimplantation

42
Q

Lab values seen in familial hypercalcemic hypocalciuria?

A

High serum Ca, low urine Ca.

HyperCa 2/2 hyperPTH has elevated urine Ca.

43
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

44
Q

Treatment for familial hypercalcemia hypocalciuria?

A

Nothing. Ca generally not that high; NO parathyroidectomy.

45
Q

What is pseudohypoparathyroidism caused by?

A

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

46
Q

5-year survival for parathyroid cancer?

A

50% 5 year survival

47
Q

Lab values in parathyroid cancer?

A

High Ca, PTH, and alkaline phosphatase

48
Q

Most common site of mets from parathyroid cancer?

A

Lung

49
Q

% of patients with parathyroid cancer recurrence?

A

50% (same as 5 yr survival rate)

50
Q

What are the tumors of MEN syndromes derived from?

A

APUD cells

51
Q

Inheritance of MEN syndromes?

A

Autosomal dominant, 100% penetrance, variable expressivity

52
Q

Tumors associated with MEN I?

A
  • Parathyroid hyperplasia (usually 1st to become symptomatic)
  • Pancreatic islet cell tumors
  • Pituitary adenoma (usually prolactinoma)
  • Correct hyperparathyroidism 1st (hyperCa exacerbates sx of panc NETs)
  • 70% have pancreas tummors - most commonly gastrinoma (insulinoma in general population)
53
Q

Tumors associated with MEN IIa?

A
  • Parathyroid hyperplasia
  • Pheochromocytoma
  • Medullary cancer of thyroid (ppx resection early)
  • Correct pheo first
54
Q

1 cause of death in MEN IIa/IIb?

A

Medullary thyroid cancer

Do ppx thyroidectomy early in life

55
Q

Tumors associated with MEN IIb?

A
  • Pheochromocytoma
  • Medullary cancer of thyroid
  • Mucosal neuromas
  • Marfan’s habitus
  • Musculoskeletal abnormalities
56
Q

Gene mutation associated with MEN I?

A

MENIN gene on chromosome 11q13

57
Q

Gene mutation associated with MEN II?

A

RET proto-oncogene on chromosome 10

58
Q

Other causes of hypercalcemia?

A
  • Malignancy
  • Hyperthyroidism
  • Immobilization
  • Granulomatous disease
  • Excess vitamin D
  • Milk-alkali syndrome
  • Thiazide diuretics
59
Q

MOA of midramycin?

A

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

60
Q

What causes a hypercalcemic crisis? Treatment?

A

Usually secondary to another surgery

Excretion: furosemide and dialysis

61
Q

What’s the next test after detecting hypercalcemia on routine lab testing?

A

PTH

62
Q

What if elevated PTH is found with normocalcemia? What needs to be ruled out before establishing diagnosis of primary hyperparathyroidism?

A

vit D deficiency, familial hypercalcemic hypocalciuria

63
Q

In a patient with parathyroid carcinoma, what is a good marker for local recurrence or metastasis?

A
  • Recurrent hypercalcemia
  • 50% recur/persist
64
Q

Patients with renal hyperPTH can develop what skin condition?

A

Calciphylaxis - precipitation of calcium and phosphorus. Can cause necrosis leading to sepsis from infection.

65
Q

How do you treat calciphylaxis?

A

If no emergent operation is needed (necrotic skin infection), then do parathyroidectomy.

66
Q

What do you do for parathyroid carcinoma found incidentally?

A

Complete an en block resection, which can include thyroid, RLN.

Prophylactic neck dissection is not useful.

67
Q

What is the workup once PHPT is revealed?

A
  • serum calcium
  • PTH
  • ALP (demonstrates bone turnover)
  • 24 hr urinary calcium (rule out FHH)
  • 25-OH vit D (rule out vit def)
  • US
  • sestamibi scan
68
Q

What is the workup for an identified MEN1 patient?

A
  • serum calcium
  • serum gastrin
  • pancreatic popypeptide levels
  • fasting blood glucose
  • serum prolactin
  • visual field testing
  • head imaging
69
Q

Recommendations for surgery in asymptomatich PHPT?

A
70
Q

What do you do with local recurrence and localized distant metastasis for parathyroid carcinoma?

A

Surgery. Chemo and radiation is not efficacious and is only used palliatively.

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