Sports supplements impact on serum creatinine and eGFR markers of renal function

Several case studies showing the impact of creatinine supplementation on eGFR results, were presented in a poster by Graeme Moyle, from the Chelsea and Westminster Hospital, London.

Estimated GFR is now routinely included in renal monitoring using the MDRD calculation, which incorporates serum creatinine, together with age, sex and ethnicity.

Six HIV-positive male patients (aged 25- 55) on stable HAART were referred to an HIV/renal clinic due to elevated serum creatinine (range 131-257 umol/L) and low eGFR. All were normal blood pressure and no history of diabetes. Proteinuria levels were normal and confirmed by urinary protein:creatinine ratio. Each patient routinely used protein and creatine supplementation as part of a muscle-building gym routine.

Three months after 5/6 patients discontinued the supplements, serum creatinine levels consistently dropped to between 98 and 118 umol/L and eGFR reported to normalise (eGFR data was not shown).

Although dietary intake of creatine is 1g/day, supplementation can increase this 20-30 fold, and intramuscular concentrations can remain elevated for several weeks. Creatine is converted to creatinine relative to its concentration which can increase serum creatinine despite normal renal function. The poster suggested that ARV exposure may also be involved but also that the association of raised serum creatinine with creatine ingestion has not been published outside of the HIV context.

This study highlights the importance taking a history of supplement use to consider this as a cause for elevated creatinine or low eGRF.

Ref: Moyle G et al. The pitfalls of the estimated glomerular filtration rate hitting the gym and creatine supplementation. 11th Intl Workshop on Adverse Drug Reactions. 26-28 October 2009, Philadelphia. Poster abstract P27. Antiviral therapy 2009; 14 Suppl 2: A49.