Berlin  - Kidney problems are a common side effect of high blood pressure, according to the German Kidney Association.

The group recommends people with high blood pressure undergo an annual urine test to check protein levels. A high level indicates the kidney is already underperforming in its filtering duties.

High blood pressure is usually identified by non-specific symptoms, like headaches or dizziness. Some people display no symptoms whatsoever.

"Loss of kidney function is often only noticed when the patient has almost reached the stage of renal failure," says Werner Riegel, president of the association.

A urine protein test is part of any annual check-up starting with age 35 and is covered by many insurers. Even people with normal blood pressure should consider the test every other year once they hit 35. (dpa)