The microalbuminuria test provides information about the amount of the protein albumin – a protein normally present in the blood – excreted in the urine within 24 hours or spontaneously. Under normal circumstances, this large, negatively charged protein is filtered out by the kidney‘s filtering apparatus and is therefore not detectable in the urine, or only in very small quantities. However, if disorders occur, albumin is present in the urine. Factors contributing to the development of microalbuminuria are:
- Level of blood pressure
- Level of glucose serum (blood glucose; BG).
- Hyperinsulinemia
- Genetic factors
- Defects of tubular reabsorption – disruption of the reabsorption of important substances by the kidney.
- Smoking
Albuminuria is considered both a diagnostic and prognostic parameter in diabetic nephropathy.
Other causes of elevated albumin:
- Acute hyperglycemia (hyperglycemia).
- Acute heart failure (cardiac insufficiency)
- Hematuria (blood in the urine)
- Urinary tract infections
- Fever
- Blood pressure crisis
- Physical exertion
- Pregnancy
The procedure
Since collecting urine over 24 hours is not always practical, one uses test strips that indicate whether albumin is present in the urine. Furthermore, it is possible to calculate the quotient of creatinine and albumin in urine from spontaneous urine.
| Material | Normal values | Microalbuminuria | Macroalbuminuria |
| Limited collection period | <20 μg/min | 20-200 μg/min | > 200 μg/min |
| 24h collection urine | <30 mg/die | 30-300 mg/die | > 300 mg/die |
| 1st or 2nd morning urine | <20 mg/l or 20 mg/g urine creatinine | 20-200 mg/l or 20-200 mg/g urine creatinine | > 200 mg/l or > 200 mg/g urine creatinine |
The higher the albumin levels rise, the more advanced the renal damage.
Indications
- Suspected glomerulonephritis – kidney disease, with inflammation of the kidney filterlets (glomeruli).
- Preventive screening* for diabetes mellitus (diabetes) and hypertension (high blood pressure).
Interpretation
Increases
- Proteinuria (excessive excretion of protein in the urine) of various genesis (cause).
- Diabetes mellitus in diabetic nephropathy (diabetic kidney disease).
Notice.
- For confirmation or exclusion of microalbuminuria, three examinations for microalbuminuria within 6-8 weeks are recommended because of sometimes considerably varying excretion rates.
- A proven microalbuminuria in two of three examinations in diabetes mellitus is considered to indicate the onset of diabetic nephropathy.
- Follow-up of existing microalbuminuria: 2-3 times a year.
Microalbuminuria and diseases
Patients with microalbuminuria:
- Have a 10- to 20-fold increased risk of developing manifest diabetic nephropathy compared with patients with no albumin excretion
- And Zust. after myocardial infarction (heart attack) have a 2-4-fold increased risk of suffering a new infarction or even cardiovascular death.
Microalbuminuria is considered an important indicator of cardiovascular disease, such as myocardial infarction and apoplexy (stroke), as well as renal insufficiency (kidney weakness). Microalbuminuria is also considered a risk indicator for cardiovascular disease in non-diabetics. The risk here is increased by a factor of 2. In cardiovascular risk patients, regular exercise reduces the incidence and severity of microalbuminuria.
