Henoch-Schonlein Purpura (HSP): Tests and Diagnosis

What tests are used to diagnose HSP?

HSP can be diagnosed and treated by your pediatrician or family doctor. If there are any questions about the degree to which kidneys are being affected, the doctor can get advice from a pediatric nephrologist (kidney specialist for kids). In a few children, the kidney problem will be serious, so your child's doctor will refer you to a pediatric nephrologist.

The following tests are typically used to diagnose HSP:

  • Urine tests show if there is blood in the urine. This will let the doctor know if the kidneys are being affected by HSP. Since body waste products are filtered from the blood by the kidneys, the doctor can tell how well the kidneys are working by measuring waste in the blood.
  • Blood tests called blood urea nitrogen (BUN) and creatinine show how well the kidneys are working. The doctor may need to check these tests more regularly until the HSP is gone to be sure the kidneys continue to function normally.

Your child’s doctor also watches for high blood pressure and high amounts of protein in the urine. Sick kidneys often cause high blood pressure (hypertension). If your child’s blood pressure is high, medication will be necessary to treat it. Keeping the blood pressure normal helps keep the kidneys and the rest of the body healthy. When the kidneys get well, the blood pressure will become normal again and the medicine can be stopped. If blood tests show the kidney function is being affected, or if there is hypertension or high amounts of protein in the urine, your doctor will refer you to a nephrologist.

You may hear about a test called a kidney biopsy. This is a test where a tiny piece of kidney is taken from one of the kidneys and looked at under a microscope. A biopsy is not needed in all cases, since the findings rarely help in deciding treatment. The results of urine and blood tests are usually enough to diagnose and treat the problem. However, a kidney biopsy may be done when there is any question about the severity of the kidney involvement, or to determine the degree of long-term kidney disease.

Typically, your child’s pediatrician or primary care provider will make the initial diagnosis of HSP after performing blood and urine tests. A nephrologist sees patients with more severely affected kidneys for treatment, but usually does not perform additional diagnostic tests.