Practice Lesson of the Week

Protein and creatine supplements and misdiagnosis of kidney disease

BMJ 2010; 340 doi: (Published 08 January 2010) Cite this as: BMJ 2010;340:b5027
  1. Joanna Willis, renal specialty trainee1,
  2. Rachael Jones, consultant HIV/GUM physician2,
  3. Nneka Nwokolo, consultant HIV/GUM physician2,
  4. Jeremy Levy, consultant nephrologist1
  1. 1Imperial College Kidney and Transplant Institute, Imperial College Healthcare NHS Trust, London W12 0HS
  2. 2Chelsea and Westminster Hospital NHS Foundation Trust, London SW10 9NH
  1. Correspondence to: J Levy j.levy{at}
  • Accepted 18 August 2009

Check dietary supplement history before investigating apparently declining renal function

The past five years has seen increasing emphasis on the early detection and treatment of chronic kidney disease, together with reporting of estimated glomerular filtration rate (GFR) alongside serum creatinine values.1 Most laboratories calculate estimated GFR automatically, using age, serum creatinine, gender, and ethnic group.2 Increasing reliance on this value as a marker of chronic kidney disease means that any factor which affects creatinine independently of true changes in renal function may lead patients to be misdiagnosed with kidney disease. Also, doctors have become more aware of the importance of reduction of estimated GFR. We report a series of patients referred for investigation of kidney disease (both acute and chronic) in whom ingestion of protein and creatine supplements led to a high serum creatinine and low reported estimated GFR in the absence of kidney disease.

Case reports

A 46 year old white man presented with a two month history of flu-like symptoms and headache and was found to be HIV positive. Routine blood tests showed a serum creatinine of 113 μmol/l (normal <115 μmol/l), giving him an estimated GFR, as calculated by the hospital laboratory, of 64 ml/min/1.73 m2 (normal >90 ml/min/1.73 m2). His CD4 count at the time of diagnosis was 320 cells ×106/l (normal >600 cells ×106/l) with a viral load of 34 344 copies/ml. HIV antiretroviral therapy was started, and one month later at routine review he was found to have a serum creatinine concentration of 166 μmol/l and an estimated GFR of 41 ml/min/1.73 m2. He was referred for …

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