Protein and creatine supplements and misdiagnosis of kidney disease

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. 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 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 …