Urinalysis is used to screen for causes of hypertension, and to look for damage to the kidneys as a result of untreated hypertension. By comparing what is present in a patient’s urine and what is present in the blood, the provider can determine how well a patient’s kidneys are functioning.

A urinalysis consists of two parts, the “dipstick,” which detects the presence or absence of certain compounds in the urine, and the “microscopic” part, where someone examines any sediment in the urine under the microscope.

The dipstick part of the test is capable of detecting protein and hemoglobin released from red blood cells. Normally, protein is too large to be filtered and so urine usually doesn’t contain any protein. Sometimes, however, untreated hypertension can cause plaque to build-up in the glomerulus as well as the small arterioles leading to and from the glomerulus. When this happens, the filtration system may “leak,” allowing protein and sometimes blood to enter the fluid that is filtered out to become urine. When blood or protein is found in the urine, it may indicate that damage due to high blood pressure has occurred. It’s important to note, however, that finding protein or blood in the urine does not necessarily mean that hypertension is the cause. These substances may be present in the urine as a result of other processes, and so further tests will probably be done.

The microscopic part of the urinalysis may reveal the presence of blood cells (hematuria), cells from the kidney itself (renal epithelial cells) or crystals that can be indicators of either kidney disease or damage to the kidney as a result of high blood pressure.