Calcium and Bone

Question 1

autoimmune polyendocrine syndrome type 1:

clinical features?

Answer 1

need 2 out of the 3 of the following: -primary hypoparathyroidism -chronic mucocutaneous candidiasis -autoimmune adrenal insufficiency

Question 2

What diabetes medications are associated with increased fracture risk in patients with type 2 diabetes?

Answer 2

pioglitazone and canagliflozin

Question 3

Treatment with recombinant human PTH 1-34 (teriparatide), an anabolic agent

1. What is the marker of bone turnover? What is the expected change after starting and stopping treatment?
2. Do the effects of teriparatide persist after stopping therapy?

Answer 3

1. osteocalcin.

• After starting treatment, osteocalcin increases
• After stopping treatment, it decreases

2. NO.

Question 4

teriparatide is contraindicated in a patient who has received prior?

Answer 4

irradiation therapy

Question 5

Case: 60 yo man with muscle and bone pain, fatigue, weakness, spontaneous fractures, and difficulty walking, low DXA scores. 1. what to measure? 2. common biochemical finding?

Answer 5

1. FGF23. It causes renal tubular loss of phosphate and inhibits 1alpha-hydroxylase (and low 1,25-dihydroxy vitamin D)
2. low 1,25-dihydroxyvitamin D levels

Question 6

In patients with pathogenic variants in the CYP24A1 gene (a rare cause of non PTH-mediated hypercalcemia), what are the common findings (3)?

Answer 6

LOW 24,25-dihydroxyvitamin D, hypercalcemia, and kidney stones, elevated 1,25-dihydroxyvitamin D

Question 7

autoimmune polyendocrine syndrome type 2:

clinical features?

Answer 7

Addison disease + either T1DM or autoimmune thyroid failure, or both

Question 8

Within the first 6 months after liver transplant, what happens to BMD?

Answer 8

there is a significant decline in bone mineral density. The high-turnover state documented after liver transplant is thought to be due to a combination of factors, including resolution of the liver disease, use of glucocorticoid therapy, and the development of secondary hyperparathyroidism due to possible renal effects of the immunosuppressant therapy. This is in contrast to the decreased bone formation and low turnover typically seen before liver transplant.

Question 9

Oncogenic osteomalacia: Lab findings?

Answer 9

Very low 1,25-dihydroxyvitamin D due to suppression by FGF23 (which is HIGH)

Question 10

TRUE or FALSE: Vertebral fractures are strong independent predictors of both future vertebral and nonvertebral fractures

Answer 10

TRUE an acute vertebral compression fracture warrants intervention with antiresorptive therapy regardless of the DXA results

Question 11

1. a urinary calcium-to-creatinine ratio <0.01 is consistent with a diagnosis of?
2. what is the caveat?
3. A patient with no identifiable CASR pathogenic variants and clinical concern for FHH should be tested for?

Answer 11

1. FHH
2. patients must be vitamin D replete ( >20 ng/ml) with good renal function for the collection to be interpretable
3. GNA11 and AP2S1 genetic testing

Question 12

1. If a patient has Paget disease, what is the next imaging modality to use?
2. For Paget disease, what are the classic biochemical findings?
3. If a patient has multiple myeloma, what is the next imaging modality to use?

Answer 12

1. bone scan
2. Elevated ALK PHOS and elevated Urinary N-telopeptide
3. skeletal survey

Question 13

What imaging will be able to determine the age of a vertebral fracture for 1-2 years after a fracture?

Answer 13

nuclear medicine bone scan

(alk pho = 6-12 mos)

(MRI = 2-3 mos)

Question 14

TRUE or FALSE

In primary hyperparathyroidism, PTH facilitates the conversion of 25-OHD to 1,25-dihydroxyvitamin D, and up to 25% of patients have frankly elevated 1,25-dihydroxyvitamin D levels

Answer 14

TRUE

Question 15

In young patients < 30 yo who present with primary hyperparathyroidism, what do you screen for?

Answer 15

MEN1 pathogenic variants -hereditary syndromes should be suspected in anyone with a personal history of other endocrine tumors (especially pancreatic or pituitary) or a family history of parathyroid disease -others include: MEN2, MEN4, and hyperparathyroidism-jaw tumor syndrome

Question 16

A rare complication of Paget disease is?

Answer 16

the transformation of the pagetoid bone into malignant osteosarcoma.

*Sarcoma should be suspected when new pain and swelling develop in a previously affected bone

Question 17

The most consistent benefit of bisphosphonate therapy in affected adults with osteogenesis imperfecta (COL1A1/COL1A2) is?

Answer 17

increased bone mineral density

Question 18

A number of studies have shown that patients who are overweight or obese require much [?] dosages of vitamin D than normal-weight participants to achieve adequate levels

Answer 18

higher Obese patients are estimated to require 2 to 3 times the usual daily dose of cholecalciferol to achieve adequate levels. The mechanism is not well understood.

Question 19

in what conditions would PTH expected to be suppressed?

Answer 19

granulomatous disease, calcitriol toxicity, humoral hypercalcemia of malignancy

Question 20

Vitamin-D resistant rickets:

1. characteristics?
2. What is the key to distinguishing vitamin D-resistant rickets from other forms of rickets?
3. In true vitamin D-DEFICIENT (not resistant) rickets, what level is 25-hydroxyvitamin D?

Answer 20

1. low serum calcium, low serum phosphate, HIGH PTH, normal 25-hydroxyvitamin D levels
2. measure 1,25 dihydroxyvitamin D: can be LOW or UNDETECTABLE in pathogenic variant in the gene encoding 1alpha-hydroxylase enzyme, but HIGH in the gene encoding the vitamin D receptor (aka true vitamin D-resistant rickets)
3. too low to be measured

Question 21

adynamic bone disease, a type of renal osteodystrophy (now called chronic kidney disease-mineral bone density disorder or CKD-MBD), is present in at least 1/3 of?

Answer 21

patients receiving dialysis

Question 22

What percentages are considered to be the least significant change in the following sites in clinical DXA studies?

1. total hip
2. femoral neck

Answer 22

1. 2.8%
2. 5%

Question 23

autoimmune polyendocrine syndrome type 3:

clinical features?

Answer 23

autoimmune thyroid disease and autoimmune disorders other than Addison disease or hypoparathyroidism More common: nonendocrine autoimmune diseases - Sjogren syndrome, alopecia areata

Question 24

1. In patients with multiple stone episodes who have already increased their fluid intake, what is the best treatment?
2. the goal is to aim for urine volume greater than?

Answer 24

1) HCTZ (enhances renal calcium reabsorption to reduce urinary calcium excretion), citrate supplements (citrate acts as a stone inhibitor) 2) 2.5 L per day

Question 25

In a patient with elevated PTH despite normal 25-OH vitamin D and serum calcium levels, what should be suspected?

Answer 25

calcium deficiency. Therefore, measure 24-hour urinary calcium excretion.