Creatine supplementation does not affect kidney function in an animal model with pre-existing renal failure.
BACKGROUND
Creatine is widely used as an ergogenic substance among athletes. Safety of prolonged creatine intake has been questioned, based upon case reports and animal data. We investigated the effect of prolonged creatine ingestion on renal function in animals with normal kidney function or pre-existing kidney failure, respectively.


METHODS
Male Wistar rats were randomly allocated to four experimental groups: (i) sham-operated, control diet; (ii) sham-operated, creatine-supplemented diet (2% w/w (0.9+/-0.2 g creatine/kg body weight/day)); (iii) two-thirds nephrectomized, control diet; and (iv) two-thirds nephrectomized, creatine supplemented diet. Glomerular filtration rate was determined using inulin and creatinine clearance, together with albumin excretion, urea clearance, muscle and serum creatine and serum cystatin C concentrations.


RESULTS
In contrast to previous reports, no detrimental effects of creatine supplementation on the renal function indices were observed in two-thirds nephrectomized or sham-operated animals. No differences were observed in inulin (0.28+/-0.08 vs 0.25+/-0.08 ml/min/100 g; P=NS) or creatinine clearance rates. Serum cystatin C concentration, urinary protein excretion, and albumin and urea clearance were comparable between creatine-supplemented and control-diet fed animals in both sham-operated and two-thirds nephrectomized animals. Serum creatine and intramuscular total creatine concentrations were higher in creatine-supplemented groups (P<0.05).


CONCLUSIONS
Creatine supplementation at a dosage of 2% w/w for 4 weeks does not impair kidney function in animals with pre-existing renal failure or in control animals.
Taes
Youri E C
YE
Laboratory of Clinical Chemistry, Department of Internal Medicine, University Hospital Ghent, De Pintelaan 185, B-9000 Ghent, Belgium.
Delanghe
Joris R
JR
Wuyts
Birgitte
B
van de Voorde
Johan
J
Lameire
Norbert H
NH
D000419:Albuminuria; D000818:Animals; D001835:Body Weight / Q000187:drug effects; D003401:Creatine / Q000378:metabolism / Q000494:pharmacology*; D004435:Eating / Q000187:drug effects; D005919:Glomerular Filtration Rate / Q000187:drug effects; D007668:Kidney / Q000187:drug effects* / Q000503:physiopathology*; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism; D051381:Rats; D051437:Renal Insufficiency / Q000378:metabolism / Q000503:physiopathology*; D012709:Serum Albumin / Q000032:analysis; D014508:Urea / Q000097:blood / Q000652:urine
D012709:Serum Albumin; D014508:Urea; D003401:Creatine