One common test measures serum creatinine, a waste product produced by normal muscle activity. The kidneys help remove creatinine from the blood, so an elevated level may indicate reduced kidney filtration. However, creatinine can also be influenced by muscle mass, hydration, certain medicines, and other factors. Doctors interpret it alongside other findings.
Another important measure is the estimated glomerular filtration rate, or eGFR. This provides an estimate of how effectively the kidneys filter blood. A low result may indicate impaired kidney function, but interpretation depends on the person’s circumstances and whether the abnormality persists.
Urine testing can provide additional clues. Blood or protein in the urine may occur in several kidney conditions. A urine albumin test can help identify small amounts of a protein that may indicate kidney damage. Other tests may be used to investigate infection or inflammation.
Doctors may also measure blood pressure and check electrolytes such as potassium and sodium. These measurements help assess how well the kidneys are maintaining the body’s internal balance. Ultrasound or other imaging may be used when clinicians need to examine the kidneys’ size, structure, or drainage.
