Calcium/parathyroid

Question 1

which pseudohypoparathyroidism subclass has normal phenotype

Answer 1

PHP 1b

Question 2

most common pseudohypoparathyroidism subclass

Answer 2

PHP 1a

Question 3

gene associated with pseudohypoparathyroidism 1a

Answer 3

GNAS

Question 4

phenotype of AHO but normal calcium/PTH

Answer 4

pseudopseudohypoparathyroidism

Question 5

difference between osteomalacia and rickets

Answer 5

osteomalacia - disorder of mature (adult) bone

rickets - disorder of growing bone

Question 6

defect in osteomalacia/rickets

Answer 6

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

Question 7

most common cause of osteomalacia/rickets

Answer 7

vit D deficiency

Question 8

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

Answer 8

1 alpha hydroxylase

Question 9

1,25-OH vit D acts on which tissues

Answer 9

intestine
kidney
parathyroid
bone

Question 10

3 categories of osteomalacia/rickets

Answer 10

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

Question 11

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

Answer 11

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

Question 12

causes of phosphate deficiency/renal wasting

Answer 12

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

Question 13

2 genetic disorders that interfere with vitamin D synthesis or action

Answer 13

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

Question 14

phosphorus metabolism is regulated by which 3 factors

Answer 14

1,25-OH vit D
PTH
FGF-23

Question 15

mechanism of XLH (x-linked hypophosphatemia)

Answer 15

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

Question 16

FRAX score assumes glucocorticoid dose in what range

Answer 16

2.5-7.5mg prednisone daily

Question 17

how should FRAX be adjusted for patients on glucocorticoids

Answer 17

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

Question 18

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

Answer 18

hyperphosphatemia from tumor lysis

Question 19

breastfeeding mother with severe osteoporosis

Answer 19

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)

Question 20

osteogenesis imperfecta pt needs to be screened for what

Answer 20

hearing loss

Question 21

most common type of osteogenesis imperfecta

Answer 21

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

Question 22

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

Answer 22

plain films with THICKENED femoral cortices

“dreaded black line” on femur xray

Question 23

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

Answer 23

ortho referral

Question 24

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

Answer 24

stop thiazide, recheck calcium/PTH in 3 months

Question 25

what happens to BMD after liver transplant?

Answer 25

significant decline within the first 6 months, then improvement

Question 26

reasons for high bone turnover after liver transplant

Answer 26

glucocorticoids | 2' hyperparathyroidism possibly due to renal effects of antirejection meds

Question 27

what happens to BMD prior to liver transplant

Answer 27

low bone turnover state

Question 28

which type of fractures has raloxifene been shown to prevent?

Answer 28

vertebral fractures | No effect on hip or other nonvertebral fxs

Question 29

side effects of raloxifene

Answer 29

VTE

Question 30

black box warning on teriperatide

Answer 30

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

Question 31

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

Answer 31

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

Question 32

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

Answer 32

prophylactic femoral rod placement

Question 33

which oral DM meds are associated with bone loss?

Answer 33

rosiglitizone | canagliflozin (but NOT dapagliflozin or empagliflozin)

Question 34

should patients with nephrotic syndrome-associated hypercholesterolemia be treated?

Answer 34

yes. statin, ezetimibe, PCSK9 inhibitor, apheresis

Question 35

phenotype of pseudohypoparathyroidism 1a

Answer 35

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

Question 36

phenotype of pseuedohypoparathyroidism 1b

Answer 36

normal

Question 37

phenotype of pseudohypoparathyroidism 1c

Answer 37

similar to 1a

Question 38

phenotype of pseudopseudohypoparathyroidism

Answer 38

similar to 1a, but no biochemical abnormalities

Question 39

how to differentiate between pseudohypoparathyroidism and vit D resistance?

Answer 39

elevated 1,25 vit D in PTH resistance

Question 40

treatment for 1st kidney stone, normal calcium/PTH

Answer 40

2L of fluids per day

Question 41

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

Answer 41

24 hour urine calcium to look for FHH

Question 42

mechanism of hypermagnesemia in FHH

Answer 42

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