Protein in urine — also called proteinuria (pro-tee-NU-ree-uh) — is an excess of bloodborne proteins in urine. Protein is one of the substances measured in a lab test to analyze the contents of urine (urinalysis).
The term "proteinuria" is sometimes used interchangeably with the term "albuminuria," but these terms have somewhat different meanings. Albumin (al-BYOO-min) is the most common type of protein circulating in blood. Some urine tests only detect an excess of albumin in urine. Excess albumin in urine is called albuminuria (al-BYOO-mih-NU-ree-uh). Proteinuria refers to an excess of multiple blood proteins in urine.
Low levels of protein in urine are typical. Temporarily high levels of protein in urine aren't unusual either, particularly in younger people after exercise or during an illness.
Persistently high levels of protein in urine may be a sign of kidney disease.
Your kidneys filter waste products from your blood while keeping what your body needs — including proteins. However, some diseases and conditions allow proteins to pass through the filters of your kidneys, causing protein in urine.
If a urine test reveals protein in your urine, your health care provider may ask you to have more testing done. 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. You also may need to do a 24-hour urine collection for lab testing.
If you have diabetes, your doctor may check for small amounts of protein in urine — also known as microalbuminuria (my-kroh-al-BYOO-mih-NU-ree-uh) — once or twice each year. Newly developing or increasing amounts of protein in your urine may be the earliest sign of diabetic kidney damage.
Show References
- McPherson RA, et al., eds. Basic examination of urine. In: Henry's Clinical Diagnosis and Management by Laboratory Methods. 24th ed. Elsevier; 2022. https://www.clinicalkey.com. Accessed Feb. 14, 2022.
- Rovin BH. Assessment of urinary protein excretion and evaluation of isolated non-nephrotic proteinuria in adults. https://www.uptodate.com/contents/search. Accessed Feb. 14, 2022.
- AskMayoExpert. Proteinuria. MayoClinic; 2021.
- Proteinuria. Merck Manual Professional Version. https://www.merckmanuals.com/professional/genitourinary-disorders/symptoms-of-genitourinary-disorders/proteinuria. Accessed Feb. 14, 2022.
- Kelepouris E, et al. Overview of heavy proteinuria and the nephrotic syndrome. https://www.uptodate.com/contents/search. Accessed Feb. 14, 2022.
- Albuminuria: Albumin in the urine. National Institute of Diabetes and Digestive and Kidney Diseases. https://www.niddk.nih.gov/health-information/kidney-disease/chronic-kidney-disease-ckd/tests-diagnosis/albuminuria-albumin-urine. Accessed Feb. 10, 2022.
Original article: https://www.mayoclinic.org/symptoms/protein-in-urine/basics/causes/sym-20050656