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Abstract & Commentary
Synopsis: Creatine supplements should be used with caution and supervision, if at all, in individuals with renal insufficiency.
Source: Edmunds JW, et al. Am J Kidney Dis. 2001;37(1):73-78.
Oral creatine supplementation has seen a huge surge in popularity since it was shown to be performance enhancing during short, high-intensity exercise. Other beneficial effects include favorable effects on lipid profiles, and neurodegenerative and musculosketelol disorders. Most of the total-body creatine is stored in muscle.
Controversy exists as to whether creatine supplementation has a detrimental effect on renal function. No controlled long-term studies are available, and most studies are small with a short duration and are comprised of only healthy subjects. Several recent reports raised serious concerns that creatine supplementation could cause serious kidney damage.1,2
To study the potential long-term effects of creatine supplementation on renal function, Edmunds and colleagues studied a rat model of renal disease. The Han: Sprague-Dawley (SPRD)-cy rat resembles human autosomal dominant polycystic kidney disease and was chosen for its short lifespan. Four-week-old male and female rats were randomized to receive a standard diet or a creatine-supplemented diet for 6 weeks. To mimic human consumption, the rats received 2.0 g/kg creatine for 1 week followed by one-fifth the dose for the next 5 weeks. Renal function was assessed with serum urea, creatinine, and creatine clearance measurements. After 6 weeks, cystic kidney disease progression was assessed by measurement of kidney size, cyst fluid content, and cyst scores.
Creatine supplementation was associated with detrimental effects after 6 weeks in this rat model. Total kidney weight increased 10%, and there was a 25% increase in cyst scores (P = .017), and a 2.1% increase in renal fluid content (P = .006). Serum urea worsened by 16% (P = .023), and creatinine clearance was reduced by 23% (P = .016) with creatine supplementation.
Comment by Kamaljit Sethi, MD, FACP
We are consuming creatine like never before—more than 2.5 million kg were consumed last year in the United States by athletes, teenagers, and others.3 The primary source of dietary creatine is meat, and 250 g of meat yields 1 g of creatine. Creatine supplementation increases skeletal muscle stores by 20% and increases short-term performance more in female athletes than in men, hence the motivation for its use as an ergogenic agent.
There are a series of questions:
1. Does creatine supplementation have an adverse effect on renal function in normal subjects? Probably not, although only short-term studies have been done.
2. Is there an adverse renal effect if high-protein intake and creatine supplements are combined in those with normal renal function? The answer is unknown and unstudied.
3. Are there deleterious effects of oral creatine supplements in those with a propensity for renal failure? If what is true of mice is true of men, then indeed deleterious renal effects may occur. Creatine supplements should be used with caution and supervision, if at all, in individuals with renal insufficiency.
1. Pritchard NR, et al. Lancet. 1998;351:1252-1253.
2. Koshy KM. N Engl J Med. 1999;340:814-815.
3. Sabatini S. Am J Kidney Dis. 2001;37:157-159.