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

18 mg²/dL² — within safe limits, no intervention needed

Answer

77.8 mg²/dL² — within acceptable range for dialysis patients

Answer

12.5 mg²/dL² — low, requires calcium supplementation

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

Calcium carbonate

Answer

Aluminum hydroxide

Answer

Calcium acetate

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

It alkalinizes the intestinal lumen to precipitate phosphate salts

Answer

It inhibits sodium-phosphate co-transporters in the intestinal mucosa

Answer

It increases renal tubular phosphate excretion

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

It blocks phosphate absorption in the gastrointestinal tract

Answer

It provides exogenous active vitamin D to suppress parathyroid gland activity

Answer

It chelates excess phosphorus in the bloodstream

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

Ergocalciferol (vitamin D2)

Answer

Alfacalcidol (1-alpha-hydroxyvitamin D3)

Answer

Cholecalciferol (vitamin D3)

Question 6

What dietary counseling is MOST effective for reducing phosphorus intake from food additives in a CKD patient?

Accepted Answer

Advise the patient to read ingredient labels and avoid foods containing words ending in '-phosphate' or '-phosphoric acid'

Answer

Instruct the patient to avoid all animal protein to eliminate phosphorus

Answer

Recommend soaking vegetables in water to leach out phosphorus

Answer

Suggest limiting potassium-rich foods, as they are always co-packaged with phosphate additives

Question 7

A peritoneal dialysis patient takes sevelamer with meals yet has persistently elevated serum phosphorus. Which assessment question should the renal dietitian ask FIRST?

Accepted Answer

'Are you taking your phosphate binders WITH each meal and snack, not before or after?'

Answer

'Have you been drinking more water lately?'

Answer

'Are you exercising regularly?'

Answer

'Have you recently reduced your sodium intake?'