What Is Orthostatic Proteinuria?

Orthostatic proteinuria is a benign condition where the urine contains slightly higher protein levels during the day. Normally, very small amounts of proteins are present in the urine, but in these patients, dipstick tests of the urine can reveal a slightly higher concentration than normal. If they are evaluated and there are no obvious causes like urinary tract infections or kidney damage, a doctor may develop a diagnosis of orthostatic, or postural, proteinuria. No treatment is required although it is advisable to monitor with followups each year to determine if the patient is developing problems.

This condition most commonly occurs in children and adolescents, although it can develop in adults. For unknown reasons, around 3% to 5% of the population loses some protein in the urine during the day while they are active; the term “orthostatic” means “upright” and means that the problem happens when people are sitting and standing. These individuals may urinate slightly more frequently during the day, and will also have a higher protein content in their urine. Overnight, their urine production drops and they have lower protein levels.

When protein in the urine is identified on a routine physical or medical workup, it can be confirmed with lab testing and the doctor may ask for additional testing of the urine to check for possible causes. For example, a child with a bladder infection would have higher proteins in the urine, and the infection would need to be identified and treated. If obvious causes are eliminated and the doctor suspects orthostatic proteinuria, the patient may be asked for what are known as divided urine samples, taken at specific times during the day to catch daytime and nighttime urine.

These samples should contain varying amounts of protein, indicating that the patient probably has orthostatic proteinuria. Doctors note the finding so discoveries of protein in the urine in the future don’t cause alarm. Once a year, the patient may be asked to submit samples for a follow-up appointment to check for complications, just in case their condition has evolved into something more serious. Many people with orthostatic proteinuria don’t experience problems.

People with this condition may want to make new health care providers aware of it. Since urinalysis is a common test in routine physicals and examinations used to learn more about new patients, it is likely that the high urine content will be noted and might be considered a cause for concern. Being aware of a prior history of orthostatic proteinuria can allow a medical provider to determine if the urine sample is truly abnormal.