CSR Bone and Mineral Metabolism in CKD (CKD-MBD) 2

Question 1

A hemodialysis patient has serum calcium of 10.8 mg/dL and serum phosphorus of 7.2 mg/dL. What is the calcium-phosphorus product and what does it indicate?

Accepted Answer

77.8 mg²/dL² — elevated, indicating increased risk of vascular and soft-tissue calcification

Answer

Ca × P = 10.8 × 7.2 = 77.8 mg²/dL², which exceeds the historical target of <55 mg²/dL² and is associated with metastatic calcification and cardiovascular mortality.

Question 2

Which phosphate binder is calcium-free and non-aluminum-based, making it preferred for patients with hypercalcemia or vascular calcification?

Accepted Answer

Sevelamer carbonate

Answer

Sevelamer carbonate is a polymer-based binder that contains neither calcium nor aluminum, reducing the risk of calcium loading and hypercalcemia while also providing an LDL-lowering effect.

Question 3

Lanthanum carbonate must be chewed with meals to be effective. What is its mechanism of phosphate-lowering action?

Accepted Answer

It binds dietary phosphate in the GI tract, forming insoluble lanthanum phosphate that is excreted in stool

Answer

Lanthanum ions released from lanthanum carbonate bind dietary phosphate in the GI tract to form insoluble lanthanum phosphate complexes that are excreted without systemic absorption of significant amounts of lanthanum.

Question 4

Cinacalcet (Sensipar) is a calcimimetic used in secondary hyperparathyroidism. What is its mechanism of action?

Accepted Answer

It activates the calcium-sensing receptor (CaSR) on parathyroid cells, increasing sensitivity to calcium and suppressing PTH secretion

Answer

Cinacalcet is an allosteric activator of the CaSR on parathyroid chief cells, making them perceive higher calcium levels and thereby reduce PTH secretion without raising serum calcium.

Question 5

Which vitamin D analog used in CKD management is synthetic, binds preferentially to the vitamin D receptor (VDR) in parathyroid tissue, and is associated with a lower risk of hypercalcemia compared to calcitriol?

Accepted Answer

Paricalcitol (19-nor-1,25-dihydroxyvitamin D2)

Answer

Paricalcitol selectively activates VDR with reduced intestinal calcium and phosphorus absorption effects relative to calcitriol, making it useful for treating secondary hyperparathyroidism with a lower risk of hypercalcemia.

(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) 2