What is Microalbumin test?

Albumin is a protein present in blood, which plays an important role in tissue growth and healing. Kidneys cannot filter albumin due to its large size, and hence this protein is not found in urine. Compared to other proteins, albumin is relatively small in size. In case of any issues at the filtration level, albumin molecules are filtered through kidneys and appear in urine. The presence of albumin in urine is called ‘albuminuria’. It is a form of ‘proteinuria’. Proteinuria or albuminuria may occur due to various diseases, such as diabetes, raised blood pressure (hypertension) or problems in kidneys.

Initially, only a small amount of albumin is seen in urine. This is called ‘microalbuminuria’. Microalbuminuria is believed to be indicative of the early onset of kidney damage, particularly in patients with diabetes or hypertension. Severe kidney damage such as in long-term diabetes mellitus or hypertension is associated with the presence of large amounts of albumin in the urine. This is called macroalbuminuria.

A microalbumin test also called as a urine albumin test, detects albumin in urine. Hence, the doctor may recommend this test to know if kidneys are working properly. 

  1. Why is a Microalbumin test performed?
  2. How do you prepare for a Microalbumin test?
  3. How is Microalbumin test performed?
  4. Microalbumin test results and normal range

A microalbumin test is advised by the healthcare professionals to identify early damage to the kidneys in patients who are at risk of developing microalbuminuria. Diabetic and hypertensive patients are usually at the risk of developing kidney damage. Hence, a regular check-up of urine microalbumin is suggested by doctors, which can detect minute amounts of albumin in urine.

The American Diabetes Association (ADA) provides detailed guidelines on the screening of patients with diabetes mellitus for the early diagnosis and management of complications. According to the ADA, patients with type 2 diabetes mellitus should be tested for microalbuminuria immediately at the time of initial diagnosis of diabetes, and annual check-ups are required thereafter. For patients with type 1 diabetes mellitus (insulin-dependent diabetes), tests for microalbuminuria should be performed five years after the initial diagnosis of diabetes followed by yearly check-ups.

As albuminuria is usually associated with diabetes, the signs and symptoms of diabetes are worth a mention. These include:

Besides diabetes and hypertension, this test is also advised for other conditions, including diseases of blood vessels, preeclampsia (raised blood pressure in pregnancy), impending kidney damage and suspected urinary tract infection.   

It is a simple urine test. The doctor may suggest a random urine sample, timed urine sample, or 24-hour urine sample. He/she would provide specific precautions or instructions regarding urine collection. This may include avoiding contamination of urine with materials, such as toilet papers or faeces. It is important to discuss with the doctor about any medications that you may be taking, as some of them, such as oxytetracyclines or other antibiotics, may interfere with test results. Also, this test can be performed with other urine tests, such as microalbumin to creatinine ratio, which may need further precautions. 

Microalbumin test or urine albumin test can be performed in different ways as mentioned above. You will be given a sterile container for collecting urine along with specific instructions based on the type of test. A random urine test is usually a one-time collection of urine in the laboratory. In a timed urine test, urine is collected for a specific predefined duration. For a 24-hour test, patients need to collect urine over a period of 24-hours;    bladder should be emptied completely in the morning, and this first sample is discarded. Thereafter, all urine samples are collected for the next 24-hours. The samples are then transported to a laboratory for examination.

Microalbumin levels in urine are usually measured in milligrams per day (mg/day). 

Normal results: Normal values of albumin in urine is less than 30 mg/24 hours (<30 mg/day) or less than 20 mg/L (10-hour collection) for an adult (laboratory normal ranges may vary slightly for different labs).

Abnormal results: Microalbuminuria, if detected in a urine test, is considered an abnormal finding. Increased levels of albumin are found in the following conditions:

  • Diabetes (kidney damage or nephropathy in diabetes)
  • Thickening of blood vessels or atherosclerosis
  • Hypertension (kidney damage or nephropathy in hypertension)
  • Nephropathy
  • Medications causing kidney damage
  • Pre-eclampsia (raised blood pressure during pregnancy)
  • Urinary tract infection

Besides these conditions, microalbumin levels may get affected in people who take protein supplements or excess salt, do vigorous exercise or in women during menstruation. If microalbuminuria is detected, the doctor may advise further investigations for proper diagnosis and treatment of the underlying condition. 

Disclaimer: All results must be clinically correlated with the patient’s complaints to make a complete and accurate diagnosis. The above information is provided from a purely educational perspective and is in no way a substitute for medical advice from a qualified doctor. 

References

  1. Wilson DD. McGraw-Hill’s Manual of Laboratory & Diagnostic Tests. Microalbumin (MA, Microalbumin/Creatinine Ratio). 2008 pp 397-399.
  2. American Diabetes Association [internet]; Kidney Disease (Nephropathy)
  3. American Diabetes Association [internet]; Diabetes Symptoms
  4. University of Rochester Medical Center [Internet]. Rochester (NY): University of Rochester Medical Center; Microalbumin (Urine)
  5. Fischbach FT. A Manual of Laboratory and Diagnostic Tests. Chapter on Microalbuminuria/Albumin (24-Hour Urine). 7th Edition. 2003.
Read on app
cross
Ask your health query from live doctors now!