What is the Best Test for Kidney Function?
There isn't one single "best" test, but rather a combination of tests provides the most comprehensive assessment of kidney function. The most important test is the glomerular filtration rate (GFR), which measures how well your kidneys filter blood. This is typically calculated using a blood test that measures creatinine levels, along with your age, sex, and race. Other tests that help assess kidney function include urine tests and, in some cases, a kidney biopsy.
- Estimated Glomerular Filtration Rate (eGFR): This is considered the best overall indicator of kidney function. It's calculated using a blood creatinine test and other factors. A lower eGFR indicates reduced kidney function. National Kidney Foundation, NIDDK, NCBI Bookshelf, UpToDate all cite GFR as the most important measure.
- Blood Creatinine Test: This measures the level of creatinine, a waste product, in your blood. Higher levels can indicate impaired kidney function. National Kidney Foundation, CDC, NIH discuss the role of creatinine in assessing kidney function.
- Urine Tests: These can detect protein (albumin) in the urine, which can be a sign of kidney damage. National Kidney Foundation, NHS, Cleveland Clinic highlight the importance of urine tests.
- Kidney Biopsy: While not a routine test, a biopsy may be necessary to determine the cause of kidney problems and assess the severity of kidney damage. Kidney Fund, Mayo Clinic mention this more invasive procedure.
Measuring both creatinine and cystatin C in blood tests can provide a more accurate estimation of GFR than using either marker alone. NIH
