What is proteinuria?
Proteinuria is the presence of protein in the urine. It can often be a sign on kidney disease. Normally, protein should not be found in the urine.
What causes protein to leak in the urine?
Healthy kidneys do not allow a significant amount of protein to pass through their filters. But filters damaged by kidney disease may let proteins such as albumin leak from the blood into the urine.
What are the different kinds of proteinuria?
Transient proteinuria — Most common form of proteinuria. Can be seen with stresses such as fever and exercise. Transient proteinuria is usually resolved on its own and does not require treatment.
Orthostatic proteinuria — Loss of protein in the urine, occurs while in an upright position but not when lying down. Occurs in 2-5% of adolescents, and is unusual in people over age of 30 years. It typically disappears with age, is not harmful and does not require treatment.
Persistent proteinuria —Protein that is always present is often a sign of underlying kidney disease or other medical problems such as hypertension and diabetes mellitus.
Who should be tested?
Patients should be tested for proteinuria if they have any of the following risk factors:
- Chronic kidney disease
- Family history of chronic kidney disease
- Cardiovascular disease
- Kidney stones or structural kidney disease
How would you doctor diagnose proteinuria?
Urine testing/ urinalysis — It can be detected by a quick dipstick test in the office; however dipstick testing is not very precise. It is very important to repeat the test, as it may be transient and repeat test can be normal. Microscopic examination of the urine is done to see if there are cells, crystals, bacteria, or structures called casts. These urine elements and suggest specific types of kidney problems.
What if protein in the urine is noted on more than two occasions?
Your doctor will send it to the lab to quantitate it.
- A single urine sample collected at any time.
- Urine that has been collected over 24 hours
Blood testing — Your doctor or nurse may also ask you to have blood tests to check your kidney function.
Kidney biopsy — Your doctor might recommend a test called a kidney biopsy, during which a doctor takes a small piece of one kidney and then looks at the tissue under the microscope. Most people with protein in the urine do not need kidney biopsy.
What are the signs and symptoms of protein in the urine?
Proteinuria may have no signs or symptoms in the early stages. Large amounts of protein in the urine may cause it to look foamy in the toilet. Swelling in the hands, feet, abdomen, or face may occur.
How is proteinuria treated?
Proteinuria is not a specific disease. Treatment depends on identifying and managing its underlying cause. If that cause is kidney disease, appropriate medical management is essential.
Untreated chronic kidney disease (CKD) can lead to kidney failure.
In mild or temporary proteinuria, no treatment may be necessary.
Drugs are sometimes prescribed, especially in people with diabetes and/or high blood pressure. These may come from two classes of drugs:
• ACE inhibitors (angiotensin-converting enzyme inhibitors)
• ARBs (angiotensin receptor blockers)
Where can you find more information?
- National Library of Medicine (www.nlm.nih.gov/medlineplus/healthtopics.html)
- National Institute of Diabetes and Digestive and Kidney Diseases(www.niddk.nih.gov)
- National Kidney Foundation (www.kidney.org)
- American Kidney Fund (www.kidneyfund.org)
- American Association of Kidney Patients(www.aakp.org)