Interestingly the word “creatinine” derives from “kreas” which means ‘flesh’ aka muscles. Pancreas is named so for being ‘pan – creas’ or ‘all flesh’ . Since muscles are the source of creatinine in our body, muscular people can have a higher baseline creatinine on labs.
After that small TED talk on muscles & creatinine, it’s useful to know that cooking meat will convert creatine in the animal’s muscles to creatinine which is then absorbed by our guts into blood ! So eating meat (and for that matter chicken or fish) can raise serum creatinine levels transiently in a patient & create a false impression of acute or worsening renal failure if labs are checked soon after eating. Here is a Feb-2022 case report published on Pubmed about the acute creatinine elevation in a patient an hour after eating boiled beef for lunch. It jumped from from 88 microMol/L to 132 microMol/L , or from 0.99 mg/dL to 1.50 mg/dL. Another study in 2014 using case-controlled healthy & CKD subjects showed a similar relation to timing of eating angus beef & checking creatinine, increases were worse with CKD.
Why is this relevant ? For patients admitted with Acute kidney injury (AKI) we often check creatinine almost daily initially until it convincingly trends down. Meat eaten within 12 hours of creatinine check can skew results showing false creatinine elevation while renal function may actually be improving, especially in patients with CKD, and may cost an extra day or two of hospital stay for monitoring.
Learning Tip 💡 : Meat, fish & chicken consumption raises serum creatinine levels transiently. It’s advisable to restrict patients admitted with AKI or CKD from eating cooked meat, chicken or fish at least in their evening meals to give enough meat-free time before checking creatinine next morning !
