The majority of individuals with early stages of CKD go undiagnosed. Hence, everyone is advised to take kidney function tests if they have any symptoms of kidney disease or if they are at high risk for kidney disease.
Kidney disease usually progresses silently, often destroying most of the kidney function before causing any symptoms. The early detection of failing kidney function is crucial because it allows suitable treatment before irreversible kidney damage or deterioration manifests itself through other complications.
Simple laboratory tests are done on small samples of blood (to measure creatinine content and estimate GFR) and on urine (to measure creatinine and albumin excretion).
Serum Creatinine: Creatinine is a waste product in your blood that comes from muscle activity. It is normally removed from your blood by your kidneys, but when kidney function is reduced, the creatinine level rises. Your doctor can use the results of your serum creatinine test to calculate your GFR, which refelcts how well your kidney is functioning.
Glomerular Filtration Rate (GFR): Your GFR tells how much total kidney function you have. It may be estimated from your blood level of creatinine. Normal is about 100 ml/min, so lower values indicate the percentage of normal kidney function which you have. If your GFR falls below 60 ml/min you will usually need to see a kidney disease specialist (called a nephrologist), If the treatment you receive from the nephrologist does not prevent a further reduction in GFR, your nephrologist will speak to you about treatments for kidney failure you might need later like dialysis or kidney transplant. A GFR below 15 indicates that you may need to start one of these treatments soon.
Urine albumin: The presence of excess protein in the urine is also a marker of CKD and is a better indicator of the risk for progression and for premature heart attacks and strokes than GFR alone. Excess protein in the urine can be screened for by placing a small plastic strip embedded with chemicals that change color when protein is present (urine dipstick) into a fresh urine specimen or can be measured more accurately with a laboratory test on the urine.
Urine albumin-to-creatinine ratio: A urine albumin-to-creatinine ratio (UACR) is a ratio between two measured substances – albumin and creatinine – in the urine. Albuminuria is diagnosed when UACR is greater than 30 mg/g and is a sign of CKD.