Albumin is a protein with various tasks in the body. It is used, for example, as a transport substance or in the distribution of fluid inside and outside the cells.
An albumin excretion in the urine, which is between 20 to 200 mg/l or 30-300 mg/24h is called a microalbuminuria. It is the mildest form of proteinuria.
The microalbumin test is a very early indicator of kidney damage. Long before manifest kidney damage, small amounts of albumin are excreted, which are not detected with a simple urine test during routine screening. Therefore, a microalbumin test with a special test strip is also carried out under certain conditions.
Albumin is a protein formed by the liver and released into the blood. Therefore, it is found in relatively high concentrations in the blood plasma.
If the kidneys are damaged, there may be an increased permeability of the filter of the kidney cells for this protein. Then albumin appears more and more in the urine.
Diabetes mellitus or arterial hypertension (hypertension) are possible causes of such a restriction of the filter function of the kidneys.
An increasing concentration of albumin is an indication of progression of kidney damage. Albumin can also appear in the urine without pathological causes, e.g. after strong physical activity.
Albumin is a relatively small protein. Therefore, it is one of the first proteins that appears in the urine with a beginning kidney damage.
If there is a suspicion of the presence of kidney disease, the urine is examined for microalbumin, or the microalbumin/creatinine quotient is also determined. Especially with diabetes or arterial hypertension, the risk of kidney damage is high. Therefore, the microalbumin test should be carried out here at least once a year.
The test is performed either from a sample of the spontaneous urine or a bulk urine sample (e.g. collection over 4 hours, overnight or 24 hours).
