Creatinine
Creatinine is a muscle-breakdown waste filtered out by the kidneys. A high level means the kidneys are clearing less than they should.
What it measures
Creatinine is produced at a steady rate by muscle metabolism and is filtered almost entirely by the kidneys. Because production is fairly constant within an individual, the blood level reflects how well the kidneys filter — high creatinine = reduced filtration. Most labs derive estimated glomerular filtration rate (eGFR) from creatinine, sex, and age. eGFR is the actually-clinically-useful number; creatinine alone can mislead in very muscular or very small-bodied people.
What a high value can mean
- Acute kidney injury — dehydration, drug toxicity (NSAIDs, contrast media, certain antibiotics), urinary obstruction.
- Chronic kidney disease — diabetes, hypertension, glomerulonephritis are the top causes.
- High muscle mass / heavy meat meal — modest rise without true kidney injury.
- Some medications — trimethoprim and cimetidine block tubular secretion of creatinine without changing actual filtration.
What a low value can mean
- Low muscle mass — elderly, frail, advanced muscle-wasting conditions.
- Pregnancy — increased filtration, normal physiology.
- Severe liver disease — reduced creatinine production.
When to discuss with a doctor
Sustained eGFR <60 (typically pairs with creatinine >1.3 in men, >1.1 in women) is the threshold for chronic kidney disease and warrants a primary-care work-up. Sudden creatinine jumps within days/weeks are acute kidney injury and need urgent evaluation. Mediora.AI plots your trajectory; treatment of CKD is highly individualised and requires a clinician.