Protein-energy wasting in maintenance hemodialysis

Hemodialysismedium

A 54-year-old man with ESRD from diabetes and hypertension, on hemodialysis for 2 years, reports fatigue and weakness. Medications include insulin, antihypertensives, aspirin, atorvastatin, sevelamer, and erythropoietin. Predialysis BP is 112/82 mm Hg. Cardiac and lung examinations are normal; he has trace leg edema. Values 3 months ago and now: albumin 3.9 and 3.4 g/dL; total CO₂ 25 and 22 mEq/L; calcium 8.7 and 8.1 mg/dL; intact PTH 400 and 600 pg/mL (dialysis target 130–585); single-pool Kt/V 1.5 and 1.43. TSH is 5.0 µU/mL with free T₄ 0.9 ng/mL (0.8–1.8). Which strategy best addresses his fatigue and weakness?

  1. A.Prescribe cinacalcet
  2. B.Conduct nutritional assessmentCorrect
  3. C.Prescribe levothyroxine
  4. D.Discontinue atorvastatin

Explanation

The most appropriate strategy is a formal nutritional assessment. This patient's fatigue and weakness are accompanied by a fall in serum albumin from 3.9 to 3.4 g/dL over 3 months, despite adequate dialysis (single-pool Kt/V 1.43) and no evidence of inflammation or volume overload to explain hypoalbuminemia. Protein-energy wasting is common in maintenance hemodialysis, affecting roughly a third or more of patients, and it presents with fatigue, loss of muscle mass and strength, and declining albumin, prealbumin, and creatinine. Low and falling albumin is among the strongest predictors of mortality in dialysis. Dialysis itself removes amino acids, metabolic acidosis (his total CO₂ has fallen to 22 mEq/L) promotes muscle protein catabolism, and diabetes, dietary restrictions, and anorexia reduce intake. The 2020 KDOQI nutrition guideline recommends routine assessment by a registered dietitian, including dietary intake, body weight trends, subjective global assessment or malnutrition-inflammation score, and protein intake estimated from the normalized protein catabolic rate, followed by individualized counseling and oral nutritional supplements when intake is inadequate. Discontinuing atorvastatin would be appropriate for true statin myopathy, which presents with muscle pain or tenderness and an elevated creatine kinase. He has no myalgias, and statin-associated weakness does not explain the falling albumin. Cinacalcet lowers PTH in secondary hyperparathyroidism, but his PTH of 600 pg/mL is near the upper end of the recommended range, his calcium is low at 8.1 mg/dL and would fall further, and secondary hyperparathyroidism of this degree does not account for his symptoms. Levothyroxine is not indicated. A mildly elevated TSH with a normal free thyroxine is common in CKD, reflecting altered thyroid hormone metabolism and nonthyroidal illness, and treating subclinical hypothyroidism in dialysis has not been shown to improve symptoms or outcomes.

Why each option

A.
Cinacalcet would worsen hypocalcemia of 8.1 mg/dL, and a PTH of 600 pg/mL near the target range does not explain fatigue.
B.
Correct. Falling albumin from 3.9 to 3.4 g/dL with adequate Kt/V and fatigue suggests protein-energy wasting, warranting dietitian-led nutritional assessment per KDOQI 2020.
C.
TSH 5.0 µU/mL with normal free thyroxine is common in kidney failure, and treating subclinical hypothyroidism in dialysis does not improve symptoms.
D.
Statin myopathy presents with myalgia and elevated creatine kinase; nonspecific fatigue with declining albumin does not justify stopping cardioprotective atorvastatin.

Reference: Ikizler TA, Am J Kidney Dis 2020 (KDOQI Clinical Practice Guideline for Nutrition in CKD: 2020 Update); Fouque D, Kidney Int 2008 (ISRNM protein-energy wasting nomenclature)

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