Protein in urine (proteinuria)

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.

• Causes