A Creatinine (CREAT) Test measures creatinine, a muscle waste product, in your blood or urine to check how well your kidneys filter waste, indicating kidney health, diagnosing disease (like CKD), or monitoring conditions like diabetes. Elevated levels signal potential kidney issues, as healthy kidneys filter it out. It’s often part of routine checks (BMP/CMP) and can involve a simple blood draw or timed urine collection, sometimes used with eGFR or albumin/creatinine ratio for a fuller picture