An Overview of Microalbuminuria

An Early Sign of Kidney Disease

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Microalbuminuria is a condition diagnosed through a urine test, and it can be a sign of kidney disease in some cases. Microalbuminuria simply indicates that a small amount of a protein called albumin is abnormally present in your urine. It is less severe than the condition albuminuria, however, which is a sign of more significant kidney disease.

Microalbuminuria indicates that your kidneys aren’t functioning optimally, and it also is a risk factor for cardiovascular disease. In the United States, it is thought to affect between roughly 6 to 10 percent of people.

Symptoms

Usually, microalbuminuria does not cause any symptoms. However, it can be one of the earliest ways to detect kidney disease. Kidney damage may become significant (and not easily reversed) before a person notices any symptoms. This is part of why it is important for people at risk of kidney disease to have the test repeatedly so that treatment can begin if necessary.

If kidney function continues to worsen, it can start to cause symptoms like swelling of the hands, feet, and face.

Causes

How the Kidney Works

To understand microalbuminuria and why it is important, it’s helpful to understand a little about how your kidneys work. Your kidneys work to filter your blood, removing substances for removal from the body via the urine. You can imagine that part of your kidneys works like a fine sieve. Normally, small molecules can pass through the sieve (and out through the urine), but larger molecules cannot.

In a healthy kidney, proteins shouldn’t be able to be detected in a urine test. That’s because protein molecules are too large to get through the “sieve.” However, if the kidneys become damaged, some protein molecules pass through the kidney “sieve” and end up in the urine. This is a condition called proteinuria. When healthcare providers find protein in the urine, it is a sign of kidney damage. Microalbuminuria just describes a type of proteinuria.

What Is Albumin?

Albumin is a small protein that is found in large amounts in your bloodstream. It has several functions, including helping keep fluid in your blood vessels and transporting certain substances through the blood.

Since albumin is a small protein as well as a common one, it makes a good laboratory marker for kidney disease. In other words, albumin is one of the first proteins that one can detect in the urine if the kidneys have become damaged. That's why it's helpful to look for it, even before symptoms from kidney disease begin.

The “micro” in “microalbuminuria” refers to the fact that only a small amount of albumin is present in the urine. If the kidney damage gets worse, the amount of albumin the urine may increase. At this point, the condition might be called albuminuria or macroalbuminuria instead. In other words, microalbuminuria indicates less severe disease than albuminuria.

What Causes Microalbuminuria?

Microalbuminuria is caused by kidney damage. Some medical conditions that can lead to kidney damage include:

  • High blood pressure
  • Type I and type II diabetes
  • Obesity and metabolic syndrome
  • Genetic inherited kidney diseases

In the United States, diabetes is the number one cause of microalbuminuria.

Diagnosis

Microalbuminuria is diagnosed based on laboratory urine tests that might be performed along with a standard medical exam. Usually, you won’t need to do anything special to prepare for the test.

There are different versions of the test that can be used. In some, you might need to collect your urine over a 24-hour period. More commonly, you might be asked to provide a urine sample at your doctor’s office. They may be able to test your sample in the office or the sample might need to be sent to a laboratory for analysis.

The urine test for albumin is often performed with another urine test, called a creatinine urine test. This sample can help the lab technicians estimate the amount of albumin in your urine over 24 hours, even if you haven’t collected your urine over that whole time.

It’s important not to confuse urine albumin tests with blood tests for albumin. Results from blood albumin tests give some different information about potential health problems than urine albumin tests.

Abnormal Levels of Urine Albumin

Technically, microalbuminuria is defined as urinary excretion of albumin between 30 and 300 milligrams of albumin per day. You also might see it defined as between 20 and 200 micrograms per minute.

Values less than that are not technically microalbuminuria. Values higher than that would be called simply “albuminuria” or sometimes “macroalbuminuria” or “proteinuria.”

Who Needs Urine Tests to Detect Microalbuminuria?

Microalbuminuria is often the first detectable sign of early kidney disease. People who are at risk of kidney disease may need to have regular urine tests for microalbuminuria. This might apply to you if you have high blood pressure, type 1 or type 2 diabetes, heart disease, obesity or metabolic syndrome, other medical conditions that increase the risk of kidney disease (like lupus), and/or a family history of kidney disease.

You also might need to have tests for microalbuminuria if you already know that you have kidney disease.

This can help your doctors monitor your condition and see how it is responding to treatment. 

Misleading Results

It’s important to note that a single medical test result indicating microalbuminuria does not necessarily mean that you have a problem with your kidneys. Doctors usually require a few different urine tests showing microalbuminuria over a couple of months before they officially diagnose microalbuminuria as a medical condition.

That’s because certain factors can increase the amount of albumin in your urine temporarily. These might include dehydration, fever, small injuries causing inflammation, recent intense exercise, urinary tract infection, certain medications, and/or increased sodium and protein in your diet.

As always, your clinician will try to interpret any laboratory results with your other medical information to get an overall impression of your health.

Treatment

Different treatments are available to address microalbuminuria. The best treatments for you may depend on the underlying causes, your other medical conditions, and other factors like your age and sex.

Lifestyle Interventions

Lifestyle interventions are an important part of treatment. These might include making dietary changes (such as reducing sugar and foods high in simple carbohydrates) as well as reducing salt intake and increasing exercise.

Many people find it helpful to work with a registered dietitian who can provide guidance about the best way to design your meals and promote weight loss if needed.

Medications

Treatment might also include medications such as:

  • Angiotensin-converting enzyme inhibitors (ACE inhibitors like lisinopril)
  • Angiotensin II receptor blockers (ARBs like losartan)
  • Other blood pressure medications
  • Medications for diabetes if needed (like metformin)

In general, if you have medical conditions that may be worsening your kidney function (like diabetes), it’s helpful to get those under better control.

Treatment Goals

Treatment goals will depend on your specific situation. In some cases, after treatment, you may no longer show signs of microalbuminuria. This is a good sign that you are helping to prevent kidney damage over the long term.

In other cases, the goal might be to stop microalbuminuria from worsening. Your kidney might already have a certain amount of damage that can’t be healed. But it’s important to work with your treatment team to prevent your microalbuminuria worsening. Taking steps to treat your condition now may help you avoid later severe kidney disease, which may later require dialysis or kidney transplantation.

Microalbuminuria and Cardiovascular Disease

Microalbuminuria is also a risk factor for cardiovascular disease, which in some people might lead to a heart attack or stroke. Microalbuminuria itself isn’t thought to cause those problems directly: it’s just an indicator.

Not everyone with microalbuminuria will have those issues, but it does somewhat increase your risk. However, some of the treatments to reduce albuminuria may also help reduce this risk. That’s another good reason to look at your whole health overall with your doctor to see how you can act in terms of prevention.

A Word From Verywell

Though there usually aren't any symptoms from microalbuminuria, it is still a condition to address seriously, especially before kidney damage becomes severe. Remember, early intervention is key. Addressing the root causes of microalbuminuria may also help you lower your risk of serious cardiovascular events, like heart attack and stroke. Work closely with your health team to find the best ways to protect your kidneys and your overall health.

Your medical team should be ready to answer all of your questions about what microalbuminuria might mean for you. Each case is different. If you get a result of microalbuminuria from a urine test, don't jump to conclusions. Discuss your results with your doctor and you can both determine the next best steps for you.

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