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ABSITE > 23 Parathyroid > Flashcards

23 Parathyroid Flashcards

1
Q

Superior parathyroids

A

4th pharyngeal POUCH

Lateral to RLN, posterior to superior portion of the gland, above inferior thyroid artery

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2
Q

Inferior parathryoids

A

3rd pharyngeal POUCH
Medial to RLN, more anterior, below inferior thyroid artery
More likely to be ectopic

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3
Q

Most common ectopic site for parathryoid tissue?

A

Tail of the thymus

Anterior mediastinum, intra-thyroid, near tracehoesophageal groove

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4
Q

Blood supply to parathyroid glands?

A

All from inferior thyroid artery

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5
Q

Effect of PTH

A

Increases serum Ca
Increased kidney reabsorption in DCT, decreases PO4
Increased osteoclasts (increase Ca and PO4)
Increased vitamin D production in kidney
Increased Ca-binding protein in intestine

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6
Q

Effect of vitamin D

A

Increase intestinal Ca and PO4 resportion

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7
Q

Effect of calcitonin

A

Decreases serum Ca
Osteoclast inhibition
Increased urinary Ca and PO4 excretion

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8
Q

MCC hypoparathyroidism

A

Previous thyroid surgery

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9
Q

Primary hyperparathyroidsim

A 
Increased Ca, decreased PO4, 
Cl to PO4 ratio > 33
Increased renal cAMP
HCO3 secreted in uring
Hyperchloremic metabolic acidosis
Sx: muscle weakness, myalgia, nephrolithiasis, pancreatitis, PUD, depression, bone pain, pathologic fracture, mental status changes, constipation, anorexia, HTN
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10
Q

Work up for primary hyperparathyroidism

A

Test calcium levels (2-3 times)
CXR (mets, sarcoid, pulmonary tumors)
Excretory urogram (nephrlithiasis, renal tumor)
Serum protein electrophoresis (multiple myeloma)
24-hr calcium (benign famililal hypocalciuric hypercalemia)
R/O MEN
Check PTH level

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11
Q

Indications for surgery in hyperparathyroidism

A 
Symptomatic disease
Asymptomatic disease:
- Ca >13
- Decreased Cr clearance
- Kidney stones
- Substantial decreased bone mass
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12
Q

Hyperparathyroidism treatment - adenoma

A

Resection

Inspect other glands to R/O hyperplasia or multiple adenoma

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13
Q

Hyperparathyroidism treatment - parathyroid hyperplasia

A

DO NOT biopsy all glands (risk of hemorrhage and hypo)

Resect 3 1/2 glands or total parathyroidectomy and autoinmplantation

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14
Q

Hyperparathyroidism treatment - parathyroid CA

A

Radical parathryoidectomy (take ipsilateral thryoid lobe)

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15
Q

Hyperparathyroidism treatment - pregnancy

A

Surgery in second trimester

Increased risk of stillbirth if not resected

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16
Q

Benefit of intra-op frozen sections in parathyroid surgery?

A

Confirm that tissue is parathyroid

17
Q

Benefit of intra-op PTH levels?

A

Determined if causative gland is removed

PTH should drop to 1/2 pre-op value within 10 minutes

18
Q

What to do if you cannot find parathyroid gland intra-op?

A

Check thymus tissue - can remove thymus tail and recheck PTH levels
Check near carotids, vertebral body, superior to pharnyx and thyroid

Still cannot find - close
- Check PTH, if still high, get Sestamibi scan

19
Q

Post-operative hypocalcemia after parathryoidectomy

A

Bone hunger - normal PTH, decreased HCO3

Aparathyroidsim - decreased PTH, normal HCO3

20
Q

Most common cause of peristent hyperparathryoidism?

A

Missed adenoma remaining in neck

21
Q

Most common cause of recurrent hyperparathyroidism?

A

Occurs after a period of hypo or normocalcemia

  • New adenoma
  • Tumor implants
  • Recurrent parathyroid CA
22
Q

Sestamibi scan

A

Preferential uptake for overactive parathyroid gland
Good for adenomas and ectopic tissue
Not good for 4-gland hyperplasia

23
Q

Secondary hyperparathyroidism

A

Renal failure
Increased PTH in respond to low serum Ca
Ectopic calcification and osteoporosis
Tx:
- Ca supplementation, Vit D, control diet PO4, PO4-binding gel, decrease aluminum
- Surgery for bone pain, fractures or pruritis

24
Q

Tertiary hyperparathyroidism

A

Corrected renal disease - autonomous PTH overproduction
Hyperplasia
Surgery

25
Q

Familial hypercalcemic hypocalciuria

A

Increased serum Ca, decreased urine Ca
Defect in PTH receptor in DCT
DX: Ca 9-11, normal PTH, decreased urine Ca
Tx: nothing, NO surgery

26
Q

Pseudohypoparathyroidism

A

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

27
Q

Parathyroid cancer

A

Increased Ca, PTH and alkaline phosphatase
Mets - lung
Tx: wide en bloc excision and ipsilateral thyroidectomy

28
Q

MEN I

A

MENIN gene
Parathyroid hyperplasia
Pancreatic islet cell tumors
Pituitary adenoma

29
Q

MEN IIa

A

RET proto-oncogene
Parathyroid hyperplasia
Medullary CA of thyroid
Pheochromocytoma

30
Q

MEN IIb

A 
RET proto-oncogene
Medullary CA of thyroid
Pheochromocytoma
Mucosal neuromas
Marfan's habitus
31
Q

Causes of hypercalcemia

A 
Malignancy
- Hematologic - lytic bone lesions
- Nonhematologic - PThrP (SCLC, breast)
Hyperparathyroidism
Hyperthyroidism
Familial hypercalcemic hypocalciuria
Immobilization
Granulomatous disease
Excess Vit D
Milk-alkali syndrome
Thiazide diuretics
32
Q

Mithramycin

A

Inhibits osteoclasts
Used with malignancy or failure of conventional treatment of hypercalcemia
AE: hematologic, liver, renal

33
Q

Hypercalcemic crisis

A

Secondary to other surgery in patients with pre-existing hyperparathyroidism
Tx: Fluids (NS), Lasix

34
Q

Breast cancer causing hypercalcemia?

A

Mets to bone cause release of PTHrP
Same with SCLC
NOT bone destruction
Increased urinary cAMP

35
Q

Hematologic cancer causing hypercalcemia?

A

Bony destruction

Urinary cAMP is low

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