CSR Bone and Mineral Metabolism in CKD (CKD-MBD) 3

Question 1

What term describes the systemic disorder in CKD encompassing abnormalities of calcium, phosphorus, PTH, and vitamin D metabolism along with bone disease and vascular calcification?

Accepted Answer

CKD-Mineral and Bone Disorder (CKD-MBD)

Answer

KDIGO coined the term CKD-MBD in 2006 to describe the broader systemic syndrome linking biochemical abnormalities, bone disease (renal osteodystrophy), and vascular/soft-tissue calcification in CKD.

Question 2

Which laboratory value is the BEST indicator of nutritional (storage) vitamin D status in a CKD patient, and should be checked before starting supplementation?

Accepted Answer

Serum 25-hydroxyvitamin D (calcidiol) level

Answer

Serum 25-hydroxyvitamin D (calcidiol) reflects hepatic storage and substrate availability for both renal and extrarenal activation, making it the standard measure of vitamin D nutritional status in all patients including those with CKD.

Question 3

A CKD G4 patient develops vascular calcification on imaging. Which phosphate management strategy is MOST appropriate according to current guidelines?

Accepted Answer

Prioritize dietary phosphorus restriction and use calcium-free phosphate binders when needed

Answer

In CKD patients with vascular calcification, calcium-based binders should be avoided or minimized to prevent additional calcium loading; calcium-free binders (sevelamer, lanthanum) are preferred alongside dietary phosphorus restriction.

Question 4

Tertiary hyperparathyroidism most commonly develops in which clinical scenario?

Accepted Answer

After kidney transplantation when autonomous parathyroid hyperplasia persists despite restored renal function

Answer

Tertiary hyperparathyroidism describes autonomous, unregulated PTH hypersecretion from hyperplastic parathyroid glands that persist after transplantation, often causing hypercalcemia and hypophosphatemia in the post-transplant period.

Question 5

Klotho, a co-receptor for FGF-23, declines progressively in CKD. What is the PRIMARY consequence of reduced Klotho expression?

Accepted Answer

Impaired FGF-23 signaling leading to phosphate retention and decreased calcitriol synthesis

Answer

Klotho deficiency in CKD blunts the kidney's response to FGF-23 (phosphaturic signal), contributing to phosphate retention; it also independently suppresses 1-alpha hydroxylase, further reducing calcitriol and worsening CKD-MBD.

(CSR) Board Certified Specialist in Renal Nutrition Practice Test

(CSR) Board Certified Specialist in Renal Nutrition Practice Test

CSR Bone and Mineral Metabolism in CKD (CKD-MBD) 3