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COMAT: Surgery > Parathyroid > Flashcards

Parathyroid Flashcards

1
Q

how many parathyroids are there?

A

usually four

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2
Q

what is the usual position of the inferior parathyroid glands?

A

posterior and lateral behind the thyroid and below the inferior thyroid artery

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3
Q

what is the most common site of an ‘extra’ gland?

A

thymus

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4
Q

if only three parathyroid glands are found at surgery, where can the fourth be hiding?

A 
thyroid gland
thymus/mediastinum
carotid sheath
tracheoesophageal groove
behind the esophagus
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5
Q

what is the embryologic origin of the superior parathyroid glands?

A

fourth pharyngeal pouch

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6
Q

what is the embryologic origin of the inferior parathyroid glands?

A

third pharyngeal pouch

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7
Q

what supplies blood to all four parathyroid glands?

A

inferior thyroid artery

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8
Q

what is the most common cause of hypercalcemia in outpatients?

A

hyperparathyroidism

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9
Q

what cell type produces PTH?

A

chief cells produce PTH

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10
Q

what are the major actions of PTH?

A

increases blood calcium levels
- takes from bone breakdown, GI absorption, increased resorption from kidney, excretion of phosphate by kidney
decreases serum phosphage

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11
Q

how does vitamin D work?

A

increases intestinal absorption of calcium and phosphate

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12
Q

where is calcium absorbed?

A

duodenum and proximal jejunum

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13
Q

define primary hyperparathyroidism?

A

increased secretion of PTH by parathyroid glands

- marked by elevated calcium, low phosphorus

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14
Q

define secondary hyperparathyroidism?

A

increases serum PTH resulting from calcium wasting caused by renal failure or decreased GI calcium absorption, rickets or osteomalacia
- calcium levels are usually low

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15
Q

define tertiary hyperparathyroidism?

A

persistant hyperparathyroidism after correction of secondary hyperparathyroidism
- results from autonomous PTH secretion not responsive to the normal negative feedback due to elevated Ca2+ levels

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16
Q

what are the methods of imaging the parathyroids?

A

surgical operation
ultrasound
sestamibi scan
CT scan

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17
Q

what are the indications for a localizing preoperative study?

A

reoperation for recurrent hyperparathyroidism

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18
Q

what its the most common cause of primary hyperparathyroidism?

A

adenoma

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19
Q

what are the risk factors for primary hyperparathyroidism?

A

family history
MEN-I and MEN-IIa
irradiation

20
Q

what are the signs/symptoms of primary hyperparathyroidism?

A

“stones, bones, groans, and psychiatric overtones”

  • stones: kidney stones
  • bones: bone pain, pathologic fractures, subperiosteal resoprtion
  • groans: muscle pain and weakness, pancreatitis, gout, constipation
  • psychiatric overtones: depression, anorexia, anxiety
  • other: polydipsia, weight loss, HTN, polyuria, lethargy
21
Q

what is the 33-to-1 rule?

A

most patients with primary hyperparathyroidism have a ratio of serum Cl- to phosphate >= 33

22
Q

what plain X-ray findings are classic for hyperparathyroidism?

A

subperiosteal bone resorption

  • usually in hand digits
  • said to be pathognomonic for hyperparathyroidism
23
Q

how is primary hyperparathyroidism diagnosed?

A

labs

  • elevated PTH, hypercalcemia, decreased phosphorus, increased chloride
  • urine calcium should be checked for familial hypocalciruic hypercalcemia
24
Q

what is familial hypocalciuric hypercalcemia?

A

familial (autosomal dominant) inheritance of a condition of asymptomatic hypercalcemia and low urine calcium, with or without elevated PTH

  • in contrast, hypercalcemia from hyperparathyroidism results in high levels of urine calcium
  • surgery to remove parathyroid glands is not indicated for this diagnosis
25
Q

what is the differential diagnosis of hypercalcemia?

A

CHIMPANZEES

  • Calcium overdose
  • Hyperparathyroidism, Hyperthyroidism, Hypocalciuric Hyprecalcemia
  • Immobility/Iatrogenic (thiazide diuretic)
  • Metastasis/Milk alkali syndrome (rare)
  • Paget’s disease (bone)
  • Addison’s disease/acromegaly
  • Neoplasm (colon, lung, breast, prostate, multiple myeloma)
  • Zollinger-Ellison syndrome
  • Excessive Vitamin D
  • Excessive Vitamin A
  • Sarcoid
26
Q

what is the initial medical treatment of hypercalcemia (primary hyperparathyroidism)?

A

medical

  • IV fluids, furosemide
  • NOT thiazide diuretics
27
Q

although most recommend surgery for asymptomatic primary hyperparathyroidism, when is it considered mandatory?

A

ROACH

  • Renal insufficiency
  • Osteoporosis
  • Age <50
  • Calcium >1mg/dL above upper limit of normal
  • Hypercalciuria >400mg/d Ca2+ excretion
28
Q

what is the definition treatment of primary hyperparathyroidism from HYPERPLASIA?

A

neck exploration removing all parathyroid glands and leaving at least 30mg of parathyroid tissue placed in the forearm muscles

29
Q

what is the definitive treatment of primary hyperparathyroidism from parathyroid ADENOMA?

A

surgically remove adenoma (send for frozen section) and biopsy all abnormally enlarged parathyroid glands (some experts biopsy all glands)

30
Q

what is the definitive treatment of primary hyperparathyroidism from parathyroid CARCINOMA?

A

remove carcinoma, ipsilateral thyroid lobe, and all enlarged lymph nodes (modified radical neck dissection for LN metastases)

31
Q

what is the definitive treatment of secondary hyperparathyroidism?

A

correct calcium and phosphate

perform renal transplantation

32
Q

what is the definitive treatment of tertiary hyperparathyroidism?

A

correct calcium and phosphage
perform surgical operation to remove all parathyroid glands and reimplant 30-40mg in the forearm if refractory to medical management

33
Q

why place 30-40mg of sliced parathyroid gland into the forearm?

A

to retain parathyroid function

- if hyperparathyroidism recurs, remove some of the parathyroid gland from the easily accessible forearm

34
Q

what must be ruled out in the patient with hyperparathyroidism from hyperplasia?

A

MEN-I and MEN-IIa

35
Q

what carcinomas are commonly associated with hypercalcemia?

A

breast cancer metastases

prostate cancer, kidney cancer, lung cancer, pancreatic cancer, multiple myeloma

36
Q

what is the most likely diagnosis if a patient has a palpable neck mass, hypercalcemia, and elevated PTH?

A

parathyroid carcinoma

- vast majority of other causes of primary hyperparathyroidism have non palpable parathyroids

37
Q

what is parathyroid carcinoma?

A

primary carcinoma of the parathyroid gland

38
Q

what is the number of glands usually affected in parathyroid carcinoma?

A

1

39
Q

what are the signs/symptoms of parathyroid carcinoma?

A

hypercalcemia, elevated PTH, PALPABLE parathyroid gland, pain in neck, recurrent laryngeal nerve paralysis, hypercalcemic crisis

40
Q

what is the common tumor marker for parathyroid carcinoma?

A

human chorionic gonadotropin (HCG)

41
Q

what are the possible postoperative complications after a parathyroidectomy?

A 
recurrent nerve injury
- unilateral: voice change
- bilateral: airway obstruction
neck hematoma
- open at bedside if breathing is compromised
hypocalcemia
superior laryngeal nerve injury
42
Q

what is ‘hungry bone syndrome’?

A

severe hypocalcemia seen after surgical correction of hyperparathyroidism as chronically calcium-deprived bone aggressively absorbs calcium

43
Q

what are the signs/symptoms of postoperative hypocalcemia

A

perioral tingling, paresthesia, +Chvostek’s sign, +Trousseau’s sign, +tetany

44
Q

what is the treatment of hypoparathyroidism?

A

actue: IV calcium
chronic: PO calcium, and vitamin D

45
Q

What is parathyromatosis?

A

multiple small hyper functioning parathyroid tissue masses found over the neck and mediastinum

  • thought to be formed from congenital rests or spillage during surgery
  • remove surgically

COMAT: Surgery (17 decks)

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