Acute creatine ingestion in human: Consequences on serum creatine and creatinine concentrations

The aim of the study was to explore the effect of an acute dose of creatine (Cr) ingestion on serum Cr and serum creatinine (Cm) concentrations. Sixte en healthy subjects ingested a single dose of Cr (20 g) followed by the mea surement of serum Cr and Cm concentration for 3 h up to a maximum of 6 h (n =6). In response to Cr ingestion a large rise in serum Cr concentration was observed (by 50 folds) occurring approximately 2 1/2 h after the ingestion (peak value of 2.17 +/- 0.66 mmol x l(-1)). We also found a moderate but s ignificant rise in serum Crn concentration averaging 13 % after 3 h (peak v alue at 99.5 +/- 10.5 mu mol x l(-1)). A dose response curve obtained in tw o case studies, in whom different doses of Cr were ingested (0, 2.5, 5, 10, 15, 20 g and 0, 10, 20, 30 g), showed that serum Cr concentration as well as the peak time increased linearly with Cr ingestion. In addition, acute C rn ingestion (5 g) resulted in a substantial increase in serum Cm concentra tion (by 10 folds) but led to a minor rise in serum Cr concentration (by 2 folds). These results suggest that when acute doses of Cr are ingested in h umans, the degree of conversion of exogenous Cr to Cm in the stomach and th e gut can be considered as negligible following the first 6 h of ingestion. However, further studies are required to explore the prolonged effect of C r on Cm metabolism.