In addition to blood values, urine values are also important for examining kidney function. If the filtering capacity of the glomeruli is impaired, protein may no longer be retained in the body and passes increasingly into the urine (proteinuria).
A healthy person normally excretes little or no protein, at most 200 milligrams of protein per day.
To assess kidney function, the concentration of the protein albumin in the urine should be checked; in a healthy person, it is less than 30 milligrams. A concentration of 30-300 milligrams of albumin is called microalbuminuria. A rapid urine test – urinalysis or urine dipstick testing – for microalbuminuria can provide the first indication of an issue with the kidneys. However, the protein concentration in the urine depends on your fluid uptake. To increase the accuracy of the test, the albumin concentration is therefore related to the concentration of creatinine in the urine in a laboratory test (albumin/creatinine quotient). Diabetics in particular should be tested regularly for microalbuminuria to assess the filtering capacity of the kidneys.
If protein is detected in a rapid urine test, further tests must be undertaken.