Calcium/parathyroid Flashcards

1
Q

which pseudohypoparathyroidism subclass has normal phenotype

A

PHP 1b

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2
Q

most common pseudohypoparathyroidism subclass

A

PHP 1a

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3
Q

gene associated with pseudohypoparathyroidism 1a

A

GNAS

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4
Q

phenotype of AHO but normal calcium/PTH

A

pseudopseudohypoparathyroidism

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5
Q

difference between osteomalacia and rickets

A

osteomalacia - disorder of mature (adult) bone

rickets - disorder of growing bone

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6
Q

defect in osteomalacia/rickets

A

mineralization of newly formed osteoid (bone protein matrix) is inadequate or delayed

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7
Q

most common cause of osteomalacia/rickets

A

vit D deficiency

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8
Q

enzyme that converts 25-OH vit D to 1,25-OH vit D

A

1 alpha hydroxylase

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9
Q

1,25-OH vit D acts on which tissues

A

intestine
kidney
parathyroid
bone

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10
Q

3 categories of osteomalacia/rickets

A

1) low calcium intake or vit D metabolism
2) disorders of phosphorus metabolism
3) small group of disorders with normal vit D/mineral metabolism

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11
Q

disorders of osteomalacia/rickets with normal vit D/phosphorus metabolism

A

hypophosphatasia
osteogenesis imperfecta
fibrogenesis imperfecta ossium
drugs (fluoride, aluminum, etidronate)

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12
Q

causes of phosphate deficiency/renal wasting

A

decreased phos intake
excessive aluminum hydroxide intake (phos binder)
x-linked hypophosphatemic rickets
autosomal dominant hypophosphatemic rickets
tumor-induced hypophosphatemia
renal tubular defects

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13
Q

2 genetic disorders that interfere with vitamin D synthesis or action

A

VDDR 1 - complete absence of renal 1-alpha hydroxylase activity
VDDR 2 - end-organ resistance to 1,25-OH vit D

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14
Q

phosphorus metabolism is regulated by which 3 factors

A

1,25-OH vit D
PTH
FGF-23

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15
Q

mechanism of XLH (x-linked hypophosphatemia)

A

inherited loss-of-function mutations in the PHEX gene, which leads to overexpression of FGF-23

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16
Q

FRAX score assumes glucocorticoid dose in what range

A

2.5-7.5mg prednisone daily

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17
Q

how should FRAX be adjusted for patients on glucocorticoids

A

if prednisone equivalent > 7.5mg daily, increase major osteoporotic fracture risk by 15% and hip fracture risk by 20%

18
Q

cause of hypocalcemia in a pt just started on chemo for lymphoma/leukemia

A

hyperphosphatemia from tumor lysis

19
Q

breastfeeding mother with severe osteoporosis

A

pregnancy/lactation-associated osteoporosis
1 or more fragility fractures within 6 months after delivery
2/3 have predisposing risk factors (fam hx, heparin use, prolonged bedrest, etc)

20
Q

osteogenesis imperfecta pt needs to be screened for what

A

hearing loss

21
Q

most common type of osteogenesis imperfecta

A

type 1
fractures in youth&raquo_space; adulthood
tx: bisphosphonates

22
Q

xray features of impending atypical femur fractures in pts on bisphosphonate therapy

A

plain films with THICKENED femoral cortices

“dreaded black line” on femur xray

23
Q

what to do if impending sign of atypical femur fractures on xray

A

ortho referral

24
Q

what to do with when mild hypercalcemia detected in pt on thiazide diuretic

A

stop thiazide, recheck calcium/PTH in 3 months

25
Q

what happens to BMD after liver transplant?

A

significant decline within the first 6 months, then improvement

26
Q

reasons for high bone turnover after liver transplant

A

glucocorticoids

2’ hyperparathyroidism possibly due to renal effects of antirejection meds

27
Q

what happens to BMD prior to liver transplant

A

low bone turnover state

28
Q

which type of fractures has raloxifene been shown to prevent?

A

vertebral fractures

No effect on hip or other nonvertebral fxs

29
Q

side effects of raloxifene

A

VTE

30
Q

black box warning on teriperatide

A

osteosarcoma

do not use in pt with hx of skeletal irradiation, Paget’s, or unexplained elevation of alk phos

31
Q

pt with nontraumatic mid-shaft femur fracture not on bisphosphonates, what is the next step?

A

image the contralateral femur for evidence of cortical thickening, which could suggest atypical femur fracture (frequently are bilateral)

32
Q

what to do if early cortical bone changes are noted on femur xrays, consistent with early atypical femur fractures?

A

prophylactic femoral rod placement

33
Q

which oral DM meds are associated with bone loss?

A

rosiglitizone

canagliflozin (but NOT dapagliflozin or empagliflozin)

34
Q

should patients with nephrotic syndrome-associated hypercholesterolemia be treated?

A

yes. statin, ezetimibe, PCSK9 inhibitor, apheresis

35
Q

phenotype of pseudohypoparathyroidism 1a

A

short, round face, short 4th metacarpal, developmental delay

36
Q

phenotype of pseuedohypoparathyroidism 1b

A

normal

37
Q

phenotype of pseudohypoparathyroidism 1c

A

similar to 1a

38
Q

phenotype of pseudopseudohypoparathyroidism

A

similar to 1a, but no biochemical abnormalities

39
Q

how to differentiate between pseudohypoparathyroidism and vit D resistance?

A

elevated 1,25 vit D in PTH resistance

40
Q

treatment for 1st kidney stone, normal calcium/PTH

A

2L of fluids per day

41
Q

pt with hypermagnesemia, high-normal serum calcium, family hx of hypercalcemia, what test to order next

A

24 hour urine calcium to look for FHH

42
Q

mechanism of hypermagnesemia in FHH

A

inactivating CASR mutation in kidney, which leads to increased tubular calcium and magnesium reabsorption