High creatinine: possible causes and what it means

Seeing that your creatinine is high tends to startle people. That makes sense, since creatinine is often mentioned in the same breath as the kidneys. Yet a raised value does not always mean something is wrong with your kidneys. In our experience, context almost always matters more than the number alone (Levey 2009).

This article expands on the overview about your kidney function, focusing on a raised creatinine.

What is creatinine?

Creatinine is a waste product from the normal work of your muscles. You make it all day at a fairly steady pace, and your kidneys filter it out. When kidneys filter less well, creatinine builds up and the value rises. There is a catch, though: creatinine also depends on muscle mass. Someone with more muscle naturally has a slightly higher value without any kidney problem.

What does a high creatinine mean?

A raised creatinine can mean your kidneys filter less well, but it is not a diagnosis by itself. You always read it in context, ideally with your eGFR, which corrects for age and sex. Creatinine can also rise temporarily through low fluid intake, fever or heavy exercise, so an abnormal result is often repeated after a few weeks.

Possible causes of a high creatinine

To see how creatinine is converted to kidney function, read on about eGFR explained, or the normal range at creatinine normal values.

Why eGFR is often clearer

Because creatinine depends so much on muscle mass, labs usually convert it to an eGFR, which accounts for age and sex. Think of a keen strength athlete: their creatinine can be on the high side while their eGFR is perfectly normal. See also creatinine.

What can you do about a raised value?

A high creatinine is a signal, not a verdict. The logical next step is a conversation with your GP, who combines it with your eGFR and symptoms. To measure your kidney values without a referral, you can have a kidney function test at Vitalcheck. A second measurement after a few weeks often says more than one result.

References

• Levey AS, et al. A new equation to estimate glomerular filtration rate. Ann Intern Med. 2009. PMID: 19414839.
• Webster AC, et al. Chronic Kidney Disease. Lancet. 2017. PMID: 27887750.
• Nierstichting. About your kidneys.

Every blood test result includes a professional assessment from a BIG-registered doctor. For treatment decisions, discuss your results with your GP.