Bone and Mineral Metabolism

Question 1

1. Which of the following cells is the main producer of
   RANKL in bone?

a. Osteoclast
b. Osteoblast
c. Osteocyte
d. Bone lining cell
e. Chondrocyte

Answer 1

b. Osteoblast

Question 2

2. Where is the major site of regulation of magnesium excretion in the kidney?
   a. Glomerulus
   b. Proximal convoluted tubule (PCT)
   c. Cortical collecting duct (CCD)
   d. Distal convoluted tubule (DCT)
   e. Thick ascending limb of the Loop of Henle

Answer 2

e. Thick ascending limb of the Loop of Henle

Question 3

3. When is measurement of parathyroid hormone-related
   peptide of greatest clinical value?

a. In the differential diagnosis of hypocalcemia
b. In pregnancy
c. In patients with hypercalcemia thought to be caused by
a tumor but with no obvious clear diagnosis of malignancy
d. In chronic kidney disease
e. In patients suspected to have primary hyperparathyroidism

Answer 3

c. In patients with hypercalcemia thought to be caused by
a tumor but with no obvious clear diagnosis of malignancy

Question 4

4. Biochemical markers of bone metabolism are of clinical
   value in—
   a. Indicating a response to treatment of metabolic bone
   disease
   b. Diagnosing osteoporosis
   c. Diagnosing osteomalacia
   d. Indicating a requirement for calcium supplementation
   e. The guidelines for recommending parathyroidectomy

Answer 4

a. Indicating a response to treatment of metabolic bone
disease

Question 5

5. Which of the following biochemical tests are of diagnostic
   value in Paget disease of bone?
   a. Parathyroid hormone
   b. Fibroblast growth factor 23
   c. Alkaline phosphatase
   d. 25 hydroxyvitamin D
   e. Acid phosphatase

Answer 5

c. Alkaline phosphatase

Question 6

6. What can cause a falsely high 25 hydroxyvitamin D measurement in many immunoassays?

a. Hypercalcemia
b. Li heparin contamination
c. Ingestion of magnesium sulfate
d. High concentration of the 3-epimer of 25OHD in the
sample
e. High concentration of 24,25-dihydroxyvitamin D in
the sample

Answer 6

e. High concentration of 24,25-dihydroxyvitamin D in
the sample