Background: Does Creatine Raise Creatinine?

A college age, extremely muscular male wants to play football in Lincoln, Nebraska. He is 6 foot, 5 inches tall. He gets a routine physical and is noted to have an elevated creatinine of 1.8. Based on his age, his eGFR suggests he is CKD Stage 3A. He does not have albumin in his urine (his uACR is less than 30).

To increase his endurance, he started using creatine to supplement his workouts. The student endorses taking 15 grams per day of creatine, purchased from a reputable establishment.

Creatine Monohydrate — Note: the recommended serving size is 5 grams. The patient was taking 15 grams.

The young man presents to the nephrologist for an evaluation of an elevated creatinine, clearance to continue to prepare for and apply to the football program, and an opinion on whether to continue creatine.

Please answer the following questions:

Describe the role of creatine in the body.

Creatine is a natural compound primarily found in muscles that helps provide energy for muscle contractions.

Creatine plays a crucial role in the body’s energy production, particularly during high-intensity, short-duration activities like lifting weights or sprinting. It aids in the rapid regeneration of adenosine triphosphate, ATP, the primary energy source for muscle contractions, leading to improved performance and muscle strength.

How can a person obtain creatine?

A person can get creatine from meat products, fish, or over-the-counter supplements.

Creatine is a naturally occurring compound found in animal products like meat and fish. It can also be obtained through dietary supplements. The body can produce creatine, but additional intake can benefit athletic performance and muscle strength.

Define creatinine and its relation to creatine.

Creatinine is a waste product formed from the muscle metabolism of creatine. It is filtered by the kidneys and excreted in urine.

creatine breaks down to creatinine — Creatine gets metabolized to creatinine

Do high levels of creatine affect the accuracy of creatinine measurements?

Yes, high levels of creatine can be misinterpreted as creatinine by laboratory analyzers, potentially leading to an incorrect diagnosis of CKD.

Our patient was taking 3 times the recommended amount of creatine.

High levels of creatine can interfere with the accurate measurement of creatinine, used to calculate the eGFR, because they have similar chemical structures.

creatine and creatinine have similar chemical structures — Initially they may not look similar, but when you look at the two molecules in the next figure as part of a chemical reaction, it makes sense how the analyzer might misinterpret one molecule for the other

When creatine is misread by the laboratory analyzers as creatinine, it can incorrectly lead to a misdiagnosis of chronic kidney disease (CKD) in a patient when the diagnosis does not exist.

How can creatine supplementation impact athletes’ performance?

Athletes often use creatine supplements to enhance their workout performance.

Creatine supplementation can increase muscle phosphocreatine stores, aiding in quick energy production during high-intensity exercise. This can lead to improved strength, power, and muscle endurance, benefiting athletes in activities requiring short bursts of intense effort.

Discussion:

➡️Learn More⬅️

Creatine for Muscle versus Creatinine for Kidney Function

Creatine and Creatinine

Creatine is a natural compound in muscles that provides energy for muscle contractions. It can be obtained from meat, fish, or supplements. Athletes often use creatine to enhance workouts.

Creatinine is a waste product from muscle metabolism. The kidneys filter creatinine from the blood and excrete it in urine at a constant rate. Creatinine is used to calculate estimated glomerular filtration rate (eGFR) which is then used to stage chronic kidney disease (CKD).

Impact of Creatine on Kidney Function Tests

Creatine can affect creatinine levels, leading to misinterpretation of kidney function. High creatine intake can be mistaken for creatinine by lab analyzers, potentially incorrectly suggesting CKD. Muscular individuals produce more creatinine than non-muscular individuals. So this patient has two reasons to have a misleading creatinine measurement: the creatine intake and his muscle mass.

For accurate kidney function assessment in such cases, the CKD-EPI creatinine-cystatin C calculation is recommended. This involves estimating eGFR using cystatin C alongside creatinine, after a period of creatine washout to eliminate its influence on the calculation.

Recommendations and Conclusion

Creatine is safe for athletes but can affect kidney function tests, making the kidney function look worse. It is crucial to remove creatine from the eGFR calculation and account for muscle mass using cystatin C to avoid the misdiagnosis of CKD.

If there are concerns about kidney function because of creatine use, or muscle mass, consulting a nephrologist for clarification is advised.

For our patient, his corrected eGFR was normal. He was cleared for play. And we told him he could continue to use creatine to train. We suggested a wash-out period during lab draw times to avoid further confusion.

Inspiration: International Society of Sports Nutrition position stand: safety and efficacy of creatine supplementation in exercise, sport, and medicine. National Library of Medicine

show less

More Interested Kidney Articles:

Why It’s Important To Calculate Total Kidney Volume In ADPKD

Michael Aaronson

August 18, 2024

Table: Calculating And Recording Daily Protein Requirements in CKD – Patient Information, Quiz