Microalbuminuria refers to a higher-than-normal amount of albumin in the urine. A high value of this urinary protein may indicate a problem with the kidneys. As people with diabetes have an increased risk of kidney complications, a doctor may request a microalbuminuria test to help detect early signs of kidney disease.

Diabetes is the leading cause of kidney disease. Some people may refer to diabetes-related kidney disease as diabetic nephropathy. The main functions of the kidneys include filtering waste products out of the blood and producing urine. The kidneys do this using filters known as nephrons. As a possible complication of diabetes, the nephrons may become thicker and develop scarring over time.

When this occurs, the kidneys may not work as well, causing proteins, such as albumin, to leak into the urine. Therefore, doctors can measure the levels of this protein in the urine to help identify early signs of kidney damage.

In this article, we discuss the association between microalbuminuria and diabetes, other factors that may contribute, and the treatment options.

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The liver produces the protein albumin, which enters the bloodstream to carry substances, such as hormones, throughout the body. When a person is in good health, this protein typically remains in the blood, and there is little or no albumin present in the urine.

Microalbuminuria is the term for when the quantity of albumin in the urine is more than the normal value but still lower than the amount a conventional dipstick may detect. Most laboratories define the rate of urine albumin excretion for microalbuminuria as 30–300 milligrams per day (mg/d). Some labs may instead define it as 20–200 micrograms per minute.

Lab technicians consider a result lower than 30 mg/d as normal and a value higher than 300 mg/d as macroalbuminuria.

Microalbuminuria suggests a moderate increase in urinary albumin, which may indicate early stage kidney disease. Macroalbuminuria may suggest kidney disease in the later stages. As such, it is advisable that people with diabetes undergo regular screening for kidney damage and take appropriate measures to lower their risk.

Diabetes is a condition that impairs the body’s ability to process blood glucose. As a result, people with diabetes may have elevated blood sugar levels that can cause complications, such as kidney damage.

The kidneys contain filters known as nephrons. These structures include a network of small blood vessels called the glomerulus, which uses a glomerular filtration system to let small molecules, such as waste products, pass through and become urine. In healthy kidneys, useful substances are too large to pass through the filter and remain in the blood. These substances include proteins and red blood cells.

High blood sugar levels can damage the blood vessels of the kidneys, which can cause inadequate filtration of blood. After many years, this damage may lead to proteins, such as albumin, leaking into the urine. As such, microalbuminuria may indicate early signs of kidney damage or kidney disease.

Evidence notes that the presence of protein in the urine, known as proteinuria, is a hallmark of diabetic nephropathy. Among people who have received a diagnosis of type 1 diabetes within the last 5 years, the prevalence of microalbuminuria is 41%. For those with type 2 diabetes, research suggests a prevalence of 25.6%.

Other factors that can contribute to the development of microalbuminuria may include:

  • Inflammation or injury affecting the kidneys
  • high blood pressure
  • fever
  • strenuous exercise
  • infections, such as a urinary tract infection
  • dehydration
  • older age
  • weight gain
  • genetics
  • preeclampsia in pregnancy
  • heart failure

Microalbuminuria has no specific symptoms. As it is a possible sign of early kidney damage, the lack of significant damage means that many people may not have any symptoms at this stage. However, some people may notice that their urine appears foamy or they have swelling that affects the hands, feet, face, or abdomen.

Due to the lack of visible symptoms, it is advisable that people at increased risk of kidney disease undergo a microalbuminuria test during their routine appointments. People who have a higher risk of kidney disease include those:

  • with diabetes
  • with high blood pressure
  • with a family history of kidney disease or kidney failure
  • aged 65 years or older
  • from certain ethnic groups, including African American, Hispanic, Asian, and Native American individuals

A person will need to see a doctor for an accurate diagnosis of microalbuminuria. The doctor may begin by asking questions about the person’s medical history, family history, and symptoms. They will also likely perform a physical examination.

The doctor will then ask for a small urine sample. No special preparations are necessary, but, in rare cases, a doctor may ask a person to collect all of their urine at home for 24 hours.

To make the test more accurate, the doctor may request an albumin-to-creatinine ratio (ACR) test. This also measures creatinine, which is a waste product of creatine, a substance that supplies energy to the muscles.

A urine dipstick test is another technique that doctors can use to check albumin levels at the time of the urine sample collection. However, this method may not always detect microalbuminuria.

Additional tests, such as imaging tests or a biopsy, may be necessary to investigate the overall health of the kidneys.

Various treatment options are available to manage microalbuminuria. The aim of treatment is to prevent further damage to the kidneys and reduce the chance of further complications.

A person may be able to reduce the amount of albumin in the urine using medications. For example, a doctor may prescribe angiotensin converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs). These drugs can help lower blood pressure, as high levels can also contribute to kidney damage.

A doctor may also recommend lifestyle changes to help reduce the amount of albumin in the urine, such as:

  • losing weight
  • exercising regularly
  • stopping smoking, if applicable
  • refraining from drinking alcohol
  • modifying the diet, such as eating less salt and protein

Due to the lack of noticeable symptoms of microalbuminuria, a person may not suspect that they have microalbuminuria. However, checking kidney function should be a regular part of a person’s health checks with their diabetes healthcare team.

People should also be mindful of changes in urinary frequency and potential signs of proteinuria, such as foamy urine and swelling.

Microalbuminuria occurs when an abnormal amount of albumin is present in the urine. Typically, this protein is unable to pass through the filtration system of the kidneys. However, when the kidneys experience damage, albumin may leak through the filter and enter the urine. As such, the presence of albumin in the urine may indicate kidney damage.

Kidney damage is a potential complication of diabetes. Therefore, a microalbuminuria test may be a useful way to identify early signs of kidney disease, allowing a person to receive appropriate treatment. It is important for people with diabetes to attend regular appointments to monitor their kidney health.