Complete Blood Count (CBC): A Blood Test That Checks Your Red Blood Cells, White Blood Cells, and Platelets

This test is a complete blood count, commonly called a CBC. It measures the main types of cells in your blood, including red blood cells, white blood cells, and platelets, and it helps your healthcare provider evaluate your overall health and detect many different conditions.

The 17-Hydroxyprogesterone (17-OHP) test measures the amount of a specific hormone in your blood. This test is done after you receive an injection of Gonadotropin Releasing Hormone (GnRH), which stimulates your body to produce certain hormones. Multiple blood samples are collected (this is the 6th specimen) to see how your adrenal glands and pituitary gland respond over time.

Your provider may order this test as part of a routine checkup, or to help find the cause of symptoms such as fatigue, weakness, fever, easy bruising, or unusual bleeding. It can also be used to monitor an existing condition, such as anemia, or to see how well a treatment is working.

Your doctor may order this test if you or your child has symptoms of a hormone disorder, such as early or delayed puberty, ambiguous genitalia, or unusual growth patterns. The test helps doctors determine if the adrenal glands are producing too much or too little of certain hormones, which can indicate conditions like Congenital Adrenal Hyperplasia (CAH) or other hormonal imbalances.

A healthcare professional will take a small sample of blood, usually from a vein in your arm. The site is cleaned, a needle is gently inserted, and the blood is collected into a tube and sent to a laboratory for analysis. The procedure typically takes only a few minutes and causes little discomfort.

A healthcare provider will first give you a GnRH injection, usually in the arm. Then, blood samples will be taken at specific time intervals (this is the 6th and final sample). Each blood draw involves inserting a small needle into a vein to collect a small amount of blood. The entire process may take several hours.

This test usually requires no special preparation, and you can normally eat and drink beforehand unless your provider tells you otherwise. Tell your provider about all medicines and supplements you take, since some can affect results. Wear a short sleeve or a sleeve that rolls up easily, and let the staff know if you have ever felt faint during blood draws.

Follow your doctor's instructions about eating and drinking before the test. Some medications may affect the test results, so inform your doctor about all medicines, vitamins, or supplements you are taking. Wear comfortable clothing with sleeves that can be easily rolled up for the blood draw.