Kidney health

Creatinine

Serum creatinine

Included in every MyHealthspan membership: Focus, Baseline, and Complete.

Your muscles make it, and your kidneys clear it.

Creatinine is a waste product made from creatine, a compound your muscles use for energy. Your kidneys filter it out of your blood, so your level helps assess how well your kidneys are working and is used to calculate your eGFR.

Your muscle mass shapes your creatinine.

Each person makes creatinine at a fairly steady rate that depends mostly on muscle mass. People with more muscle tend to have higher levels, and people with less muscle tend to have lower levels, even with healthy kidneys.

Short-term factors can shift it too. Intense exercise, a large meat meal, creatine supplements, dehydration, and some medications can raise creatinine. That's why a single result is read with your eGFR, your history, and sometimes a repeat test.

Creatinine reflects your muscles as well as your kidneys.

Questions

Do creatine supplements affect my result?

They can. Creatine supplements are linked with a modest rise in blood creatinine, which can make kidney function look lower than it is. Let your clinician know if you take them. A cystatin C test can help clarify the picture if needed.

How can I get the most representative result?

Avoid unusually hard exercise and very large meat meals in the hours before your blood draw, and stay normally hydrated. If you take creatine or other supplements, mention them when you review your results.

Sources and references