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ER part 1 > 020215 parathyroid gland > Flashcards

020215 parathyroid gland Flashcards

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1
Q

effects of PTH

A

kidney: increases calcium reabsorption, decreases phosphate reabsorption, converts 25-hydroxyvit D to 1,25-dihydroxyvit D
intestine: increases calcium and phosphate absorption through 1,25D
bone: increases calcium and phosphate resorption

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2
Q

calcium sensing receptor on parathyroid cell can have what kinds of mutations

A

loss of fxn familial hypocalcinuric hypercalcemia (FHH)

gain of fxn autosomal dominant hypocalcemia (ADH)

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3
Q

calcimimetic (cinacalcet)

A

can be used to tx severe hyperparathyroidism

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4
Q

symptoms of hypercalcemia

A

most ambulatory pts-no clear symptoms

fatigue, weakness
nausea, vomiting, constipation
anorexia
polyuria, polydipsia
dehydration
memory impairment
drowsiness, confusion, coma
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5
Q

vicious cycle of hypercalcemia

A

hypercalcemia leads to renal salt and water loss, which leads to ECF volume contraction, which leads to decreased Ca excretion, which aggravates hypercalcemia (can’t excrete Ca)

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6
Q

hypercalcemia is caused by

A

increase in PTH secretion (primary hyperparathyroidism-usually a parathyroid adenoma)

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7
Q

causes of hypercalcemia- PTH dependent

A

primary hyperparathyroidism:

  • -sporadic (single and multiple gland disease, carcinoma)
  • -multiple endocrine neoplasias
  • -hyperparathyroidism jaw tumor syndrome
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8
Q

physiological findings for primary hyperparathyrdoidism

A

decreased sensitivity of PTH-secreting cells to inhibition by plasma Ca

increased or inappropriately not suppressed serum PTH

hypercalcemia

hypophosphatemia

some pts: hypercalciuric

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9
Q

genetics of familial hypocalciuric hypercalcemia (FHH)

A

FHH1-most families-Ca sensing receptor mutation that causes parathyroid cell to not sense Ca and the kidney tubule cell to not sense Ca so that more Ca is reabsorbed

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10
Q

tx of FHH and primary hyperparathyroidism

A

FHH-don’t do surgery

primary hyperparathyroidism-surgery

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11
Q

bone fibrosis

A

severe primary hyperparahthyrodism

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12
Q

most common cause of PTH-independent hypercalcemia

A

malignancy (bone metastases, PTH-related protein, osteoclast activating factors, unregulated calcitriol production, true ectopic PTH)

calcitriol-mediated (granulomatous, inflammatory). calcitriol is 1,25(OH)2D

hyperthyroidism (increases bone resorption)

milk-alkali syndrome or calcium alkali syndrome (pt consumes huge amts of Ca carbonate)

immobilization (bone resorption)

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13
Q

PTHrP

A

parathyroid hormone related peptide

can be secreted by tumor cells (breast, lung, kidney, squamous)

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14
Q

how does calcitriol-mediated hypercalcemia come about?

A

non-renal or unregulated expression of 1-hydroxylase by:

sarcoid
lymphoma

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15
Q

hypercalcemia can be divided into what two causes

A

PTH dependent

PTH independent

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16
Q

if it’s PTH dependent hyperparathyroidism, what tests can you do to determine cause

A

24 hr urine calcium and creatinine to determine if it’s primary hyperparathyroidism or FHH

17
Q

tx of hypercalcemia

A

normal saline IV fluid (pts are dehydrated often)
loop diuretics (furosemide)–augment Ca excretion
calcitonin
BISPHOSPHONATES (inhibit osteoclastic bone resorption)

18
Q

signs and symptoms of hypocalcemia

A 
neuromuscular irritability (paresthesias, muscle cramps, tetany)
lowered seizure threshold
mental status changes
cardiac-prolonged QT, arrhytmias, CHF
basal ganglia calcification
cataracts
positive Chvostek's, Trousseau's signs
19
Q

basal ganglia calcification

A

hypoparathyroidism

20
Q

Chvostek sign

A

tapping of facial nerve causes muscle spasm

positive in hypocalcemia

21
Q

Trousseau sign

A

filling of blood pressure cuff causes muscle spasm

positive in hypocalcemia

22
Q

causes of hypoparathyroidism

A

genetic disorders
autoimmune
infiltrative
pseudohypoparathyroidism (PTH resistance)–type 1a has GNAS mutation and Albrights hereditary osteodystrophy

23
Q

signs of pseudohypoparathyroidism

A

short stature
short 4th and 5th fingers
round face

24
Q

diagnosing hypercalcemia

A

see slide 22

25
Q

diagnosing hypocalcemia

A

see slide 32

26
Q

tx of hypocalcemia

A

acute-IV calcium gluconate

chronic due to hypoparathyroidism-calcium supplements and either vitamin D2, D3, or calcitriol

27
Q

FGF23

A

fibroblast growth factor 23
made by osteocytes

increases urinary phosphate excretion
decreases renal production of 1,25(OH)2D

excess FGF23 causes hypophosphatemia and impaired bone mineralization

decreased FGF23 causes hyperphosphatemia and tumoral calcinosis

28
Q

causes of hypophosphatemia and hyperphosphatemia

A

see paper

29
Q

how to categorize hypocalcemias

A

PTH dependent
PTH independent
see slide 32

30
Q

what happesn to urinary Ca in secondary hyperparathyroidism?

A

it’s low (b/c kidney trying to hang onto calcium)

ER part 1 (19 decks)

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