protein in urine

Evaluation for Protein in Urine

The kidneys remove wastes and excess water and salts from the blood. Kidneys receive blood through the renal arteries. The blood flows into parts of the kidney called nephrons. Each nephron is made of a glomerulus and a tubule. Each kidney contains thousands of nephrons.

The glomeruli filter the blood, removing waste products from the blood. They also prevent some substances, such as protein, from being taken out of the blood. If the glomeruli are damaged, protein from the blood leaks into the urine.

Normally, you should have less than 150 milligrams of protein in the urine per day. Having more than 150 milligrams per day is called proteinuria. This can be detected on a routine urinalysis.


Most people with proteinuria have no signs or symptoms. However, some patients have edema (swelling) in the face, legs, or both.

The urine may also appear bubbly or soapy, like a beer with a head on it.


Proteinuria is diagnosed by analyzing the urine (called a urinalysis), often with a dipstick test. However, dipstick testing is not very precise. Most people need to have the urine test repeated. It is common to have proteinuria temporarily, and repeat urine tests are usually normal.

The urine will also be examined with a microscope to see if there are cells, crystals, bacteria, or structures called casts. These things can be a sign of another kidney problem, called glomerular disease.

If two or more urinalyses show protein in the urine, the next step is to determine how much protein is in the urine. This can be measured from:

  • A single urine sample collected at any time (this is the most common method).
  • Urine that has been collected over 24 hours.

Blood testing — You may be asked to have blood tests to see how well your kidneys are working (called kidney function testing). This includes measurement of BUN (blood urea nitrogen), creatinine, and then calculating how well the kidneys work with a formula called glomerular filtration rate.

Renal biopsy — After your initial evaluation and review of additional testing, the REHC nephrologist might recommend a test called a renal biopsy. During a biopsy, a doctor takes a small piece of one kidney and then looks at the tissue under the microscope. Most people with proteinuria will not need a kidney biopsy.

Usually a nephrologist is called when your doctor sees a change on your blood test called a creatinine. When the creatinine goes up, the kidney is not getting rid of creatinine and that is how we know there is a kidney problem. The procedure includes urinalysis. kidney ultrasound and other blood tests that might show a reason why and how the kidney has been injured.

Many types of medications and fluids can be used to treat acute kidney injury depending on the cause.

We treat the underlying cause of kidney problem and this will usually stop many of the symptoms, so our patients typically don’t experience any distress while they are having the problem treated.

Treatment and prognosis:

Transient and orthostatic proteinuria are not harmful conditions and no treatment is needed.

Patients with persistent low-grade proteinuria that is not related to decreased kidney function or a systemic disease typically have no long-term complications, even if untreated. Many nephrologists use an antihypertensive drug, such as an angiotensin converting enzyme (ACE) inhibitor, to reduce or eliminate proteinuria.

In patients with persistent high-grade proteinuria who have decreased kidney function, the underlying condition is usually treated.

Copyright by Florida Kidney Physicians.