Albuminuria

Albuminuria is a sign of kidney disease that occurs when too much albumin, a protein normally found in your blood, appears in your urine. This condition can serve as an important warning sign for kidney damage and related health problems.

proteinuria, microalbuminuria

Table of contents

• What is Albuminuria?
• Who is at Risk?
• Why Testing for Albumin Matters
• How is Albuminuria Detected?
• Treatment and Management

What is Albuminuria?

Albuminuria is a sign of kidney disease and means that you have too much albumin (a protein found in the blood) in your urine^[2]. A healthy kidney does not let albumin pass from the blood into the urine. When the kidneys are damaged, some albumin passes into the urine. The less albumin in your urine, the better^[2].

Albumin is a type of protein made up of amino acids. It helps move hormones, nutrients, and enzymes throughout your body via your bloodstream. Albumin is the most common type of protein in your blood, making up about half of the total proteins found in your blood plasma^[10]. Albumin is produced in your liver and is mostly stored and used in your blood^[10].

The term proteinuria is sometimes used interchangeably with albuminuria, but these terms have somewhat different meanings. While proteinuria refers to an excess of multiple blood proteins in urine, albuminuria specifically refers to excess albumin in urine^[4]. Albuminuria is the most common form of proteinuria^[8].

Who is at Risk?

Albuminuria usually develops because of a problem with your kidneys. When the filtration system in your kidneys is not working well, too much protein can move into your urine^[10]. Albuminuria occurs in as many as 10% of representative samples of US adults^[5].

People who have diabetes, high blood pressure, heart disease, or a family history of kidney failure are at risk for kidney disease^[2]. As hypertension, diabetes, and obesity are each associated with albuminuria, it should not be surprising that the increased prevalence of these disorders has resulted in a corresponding increase in the prevalence of albuminuria^[5].

People over the age of 65 and those with certain racial or ethnic backgrounds—such as African Americans, Asian Americans, Hispanic people, and Native Americans—also have an increased risk of kidney diseases^[10]. Chronic kidney disease (a condition where the kidneys gradually lose their ability to filter waste from the blood) is one of the main issues that can lead to albuminuria^[10].

Why Testing for Albumin Matters

Measurement of urine albumin is an important tool for diagnosing kidney disease and monitoring the progression of kidney disease^[2]. Healthcare providers regularly test people for albuminuria as part of a routine medical exam and will closely monitor urine albumin in people with kidney disease^[2].

Albuminuria is an important risk marker for adverse cardiovascular (heart and blood vessel) and kidney outcomes and mortality. The relationship between albuminuria and risk is continuous and linear, like that of blood pressure and cardiovascular risk^[5].

A urine albumin level that stays the same or goes down may mean that treatments are working. Treatment that lowers the urine albumin level may lower the chances that kidney disease will progress to kidney failure^[2]. In high-risk patients, routine annual screening can detect changes in urine albumin excretion and improve the timely identification of albuminuria^[5].

Healthcare providers should discuss with patients how often they should get a urine test for albumin^[2].

How is Albuminuria Detected?

A healthcare provider often tests for albuminuria using a urine dipstick test (a simple test using a chemically treated strip of paper) followed by a urine albumin and creatinine (a waste product filtered by the kidneys) measurement^[2]. You will be asked to collect a urine sample in a special container in your healthcare provider’s office or a commercial facility. The office or facility tests the sample onsite or sends it to a lab for analysis^[2].

For the dipstick test, a nurse or technician places a dipstick into the urine. The dipstick changes color if albumin is present in the urine^[2].

A healthcare provider uses the albumin and creatinine measurement to determine the ratio between the albumin and creatinine in the urine and to estimate the amount of albumin excreted in 24 hours^[2]. Preferred simple screening methods appropriate for use in the primary care setting include microalbumin-specific dipsticks and urinary albumin:creatinine ratio determination from a spot urine sample^[5].

Low levels of protein in urine are typical. Temporarily high levels of protein in urine are not unusual either, particularly in younger people after exercise or during an illness. However, persistently high levels of protein in urine may be a sign of kidney disease^[4]. Because protein in urine can be temporary, you may need to repeat a urine test first thing in the morning or a few days later^[4].

Treatment and Management

With lifestyle changes and proper medical treatment, you can reduce your microalbumin levels^[2]. Cornerstones of albuminuria treatment include risk factor management, ongoing monitoring, and, in patients with hypertension, chronic kidney disease, or diabetes, the use of renin-angiotensin-aldosterone system (RAAS)–blocking agents (medications that help control blood pressure and protect the kidneys)^[5].

Taking medications as prescribed by your doctor is one of the best ways to help reduce the protein in your urine. Whether you have stable disease or a flare, medications are a key component in managing albuminuria. Certain medications reduce protein in the urine by controlling blood pressure; newer medications are working in other areas to target protein in the urine^[15]. Both angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) have demonstrated utility in this regard^[5].

High blood pressure causes kidney damage and is a side effect of kidney disease. Keeping blood pressure in check is crucial to slowing kidney damage. Most guidelines recommend a blood pressure below 130/80 mm Hg for individuals with kidney disease^[15]. Lifestyle adjustments such as reducing salt intake, engaging in regular physical activity, and managing stress can help keep blood pressure under control^[15].

Diet plays a significant role in managing albuminuria and reducing proteinuria. Consistently following a healthy diet can help protect your kidneys and lessen your protein leakage into urine. This includes reducing sodium (excessive salt can worsen blood pressure and fluid retention), with an aim for less than 2,300 mg per day^[15]. Limiting protein intake is also important, as too much dietary protein can strain the kidneys and increase protein leakage into the urine. The appropriate amount depends on your stage of kidney function, and the source of protein also matters—plant proteins have been shown to be easier on the kidneys than animal protein sources^[15].

You can lower albuminuria by eating a low-protein, low-fat, low-sugar diet, exercising regularly (ideally 30 minutes a day), and taking prescribed medications according to your doctor’s instructions^[16]. Focus on fruits and vegetables, legumes, nuts, whole grains, fish, and low-fat dairy products while limiting red or processed meats, sodium, and sugar-sweetened beverages like soda^[16].

It is essential to know your medication needs can change over time. Keeping a blood pressure log so that your doctor can make accurate adjustments to your medicine is a proactive way to prevent kidney damage^[15].