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Chapter 21: Chronic Kidney Disease-Mineral Bone Disorder

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A 50-year-old patient presents with end-stage kidney disease (ESKD) secondary to diabetes on hemodialysis thrice weekly 4 hours each treatment. Her monthly laboratory tests show calcium of 9.2 mg/dL, phosphorus of 7.8 mg/dL, and PTH of 200 pg/mL and stable. She is taking four sevelamer and two calcium acetate drugs with each meal, but some days she has problems taking them due to gastroparesis. The phosphorus levels have been progressively rising despite dietary counseling and multiple phosphate binder changes. She states that she cannot cook for herself due to visual impairment and thus frequently eats processed foods. She also has difficult chewing due to loss of many teeth. Which of the following options will have the greatest impact on her serum phosphorus level?

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A. Continue dietary counseling.

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B. Change phosphate binder to lanthanum as it is a more potent binder than sevelamer.

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C. Encourage the patient to change to daily or nocturnal dialysis if her family is willing to help.

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D. Prescribe a calcimimetic.

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E. Prescribe calcitriol.

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The answer is C. If the patient continues to eat nonprocessed foods and has difficulty tolerating binders, daily or nocturnal dialysis is the best option. Lanthanum is contraindicated if she cannot chew, and calcimimetics and calcitriol are not indicated at her level of PTH.

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A 32-year-old African–American woman comes to your clinic with newly diagnosed CKD from poorly controlled hypertension and nonsteroidal anti-inflammatory drug (NSAID) use. Her estimated GFR is 25 mL/min, phosphorus is 4.9 mg/dL (NL range 3.2–4.7 mg/dL), calcium level is 9.2 mg/dL, and PTH is 90 pg/mL (NL up to 65 pg/mL). You have no previous phosphorus levels available. What do you do about the elevated phosphorus level?

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A. Begin treatment with sevelamer 800 mg po tid.

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B. Begin treatment with calcium acetate 667 mg po tid.

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C. Repeat the phosphorus level next visit.

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D. Recommend she avoid processed foods and repeat the phosphorus level next visit.

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The answer is D. Phosphorus levels can vary widely due to dietary intake and diurnal variation. There is no data that phosphate binders impact clinical outcomes at this stage of CKD, and thus interventions are indicated only to lower a biochemical value. Thus, care should be taken to ensure the level is clearly abnormal prior to implementing drug therapy. However, given her stage of CKD, she would benefit from avoiding processed foods as a mechanism to lower both dietary phosphorus and sodium intake.

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