Recently a really worried athlete approached ISST with his recent blood work ordered by the doctor (a reputed MD in his field). The blood work showed his serum creatinine levels at 7! The normal range for the same is between 0.6 to 1.1 mg/dl.
After seeing this report, doctor recommended him an immediate dialysis as this high of the creatinine levels are only visible in renal failure cases.
Now, this young athlete told me that he had no past history of any steroid use or other medications/drugs, nor were any symptoms present. But many a time in a Kidney disease symptoms may be subtle or may not appear at all. So based on this info alone absence/presence of kidney disease can’t be ruled out.
On further investigation about his daily nutrition and supplemental routine, he revealed that lately, he had swapped his regular creatine monohydrate supplement with a new creatine ethyl-ester product.
This was an AHA moment!
I asked the athlete that whether he had shared this information with the doctor to which his response was negative. I asked him to immediately inform the doctor about it because creatine supplementation does increases the serum creatinine levels. Plainly further investigation is required to check into kidney functioning.
Now, this was where the things got really interesting and persuaded me to write this piece. When this athlete approached the doctor with the new information, the doctor hesitated at first but then ordered a next test for the urine analysis to check the creatinine levels present in urine. Turned out that his urine creatinine levels were too out of whack.
And next, the doctor told him to immediately stop this new supplement, as clearly (according to Doc) it was affecting his kidney functioning and creating damage. He also prescribed him with a list of other drugs to start immediately. Dialysis was still not off-list.
What’s going on here?
Creatine and Creatinine
Creatinine is a chemical waste product produced by muscle metabolism. When your kidneys are functioning normally, they filter creatinine and other waste products, say urea out of your blood. These waste products are removed from your body through urination.
Each day, 1-2% of muscle creatine is converted to creatinine. Men tend to have higher levels of creatinine than women because, in general, they have a greater mass of skeletal muscle. Increased dietary intake of creatine or eating a lot of protein (like meat) can increase daily creatinine excretion.
It’s been observed that a 5 grams/day dose of creatine monohydrate supplement increases the serum creatinine levels by 2 to 3 times the normal after a period of 8 to 12 hours. And designer creatine supplement (like the one our guy was taking) can raise the serum creatinine levels up to 6 to 7 times!
Now in our athlete’s case, the serum and urine creatinine levels were both elevated which indicates that kidneys are working in good order as far as creatinine clearance (CrCl) is concerned. And since the filtration rate (eGFR) was normal, there was nothing to be worried about.
The elevated creatinine levels have ZERO clinical significance here. Our athlete is perfectly safe.
The creatinine test is NOT a valid indicator of kidney disease in the case of creatine supplement users.
Moreover, studies suggest that supplemental creatine does not impair the kidney functioning in any way. Even it was observed that in a person with only one kidney using a large dose of creatine (20 grams/day) had no effect on kidneys.
Creatine supplementation is safe for a healthy individual.
And I don’t really blame medical practitioners or doctors for such ignorance because they’re not well-versed in sports nutrition and supplementation. How can you blame someone for something that one is not even trained for?
One caveat though, if you already had some sort of kidney problem and you’re on diuretic drugs, then creatine may interfere with your treatment. Besides, if while taking supplemental creatine your serum creatinine levels are high but urine creatinine level does not correspond, this indicates that your kidney health is not up to snuff. But it should be a common sense to both you and your doctor. Right?
- Gualano B, et al. Effect of short-term high-dose creatine supplementation on measured GFR in a young man with a single kidney. Am J Kidney Dis. (2010)
- Stevens LA, Coresh J, Greene T, Levey AS (June 2006). “Assessing kidney function–measured and estimated glomerular filtration rate”. The New England Journal of Medicine. 354 (23): 2473–83.
- Physiology: 7/7ch04/7ch04p11 – Essentials of Human Physiology – “Glomerular Filtration Rate”