Blood and urine testing in CAHThe reason for testing the blood and urine of CAH patients is to ensure that just enough medication is being given to control overproduction of androgen and no more. The test results are interpreted in conjunction with the results of a physical examination. In the blood, we are interested in the levels of a particular chemical called 17-hydroxyprogesterone (sometimes abbreviated to 17OHP) and plasma renin activity (PRA). An elevated level of 17OHP means that the adrenal glands are too active, and an increase in cortisone may be needed. A high level of plasma renin activity (PRA) means that the salt level in the body is low. In the urine, we measure pregnanetriol. This is derived from 17OHP, but since the urine is collected over 24 hours, the pregnanetriol level in the urine may give a better idea of overall control than the 17OHP level does. At the Royal Children's Hospital, we measure 17OHP, PRA and pregnanetriol every three months. Other clinics may do things differently. Adults with CAH do not need to be tested as frequently as children because they are no longer growing.
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