Blood Test (Laboratory Test): What It Is, How It Is Done, and What Your Results Mean

What is this test? A blood test is a common laboratory procedure in which a small sample of your blood is collected and analyzed to evaluate your overall health, screen for diseases, help diagnose symptoms, or monitor a condition you already have.

The androstenedione challenge test measures the amount of androstenedione in your blood. Androstenedione is a hormone produced by the adrenal glands (small glands on top of your kidneys), as well as by the ovaries in women and testes in men. This test is called a "challenge" or "stimulation" test because it involves giving you a stimulating agent (usually ACTH - adrenocorticotropic hormone) to prompt your adrenal glands to produce more hormones. Blood samples are taken before and 20 minutes after the challenge to see how your body responds.

How is the test performed? A trained healthcare professional will clean the skin on the inside of your elbow or the back of your hand, wrap a band around your upper arm, and insert a thin needle into a vein to draw a small amount of blood into one or more tubes. The sample is then sent to a laboratory for analysis, and the puncture site is covered with a small bandage. The procedure usually takes only a few minutes.

The test typically involves the following steps: First, a healthcare professional will insert a small needle into a vein in your arm to draw a baseline blood sample. Then, you will receive an injection of a stimulating hormone (usually synthetic ACTH). After exactly 20 minutes, another blood sample will be drawn from the same or a different vein. The entire procedure usually takes about 30-45 minutes. The blood samples are then sent to a laboratory to measure androstenedione levels.

Why might I need this test? Your doctor may order a blood test as part of a routine checkup, to help diagnose symptoms such as fatigue, fever, weakness, or unexplained pain, to confirm or rule out an infection, to check how well organs such as the liver, kidneys, or thyroid are working, or to monitor how well a treatment or medication is controlling an existing condition.

Your doctor may order this test if you have symptoms of a hormonal disorder, such as irregular periods, excessive hair growth (hirsutism), acne, or infertility in women; or early puberty, muscle mass changes, or testicle problems in men. It helps distinguish between adrenal gland problems and other causes of hormone imbalances. The test is also used to monitor response to treatment for certain conditions.

How should I prepare for the test? Follow any specific instructions from your healthcare provider, because some blood tests require fasting for 8 to 12 hours beforehand, meaning you should not eat or drink anything except water. Stay well hydrated unless told otherwise, wear sleeves that can be rolled up easily, and tell your provider about all medications, vitamins, and supplements you take, since some of them can affect your results.

Follow your doctor's instructions carefully. You may need to avoid certain medications (especially steroids or hormonal treatments) before the test, as they can affect the results. Inform your doctor about all medications and supplements you are taking. Fasting is usually not required, but follow specific instructions if given. Wear comfortable clothing with sleeves that can be easily rolled up. The test is generally safe, but inform your healthcare provider if you have any allergies or have had reactions to previous stimulation tests.

What do the results mean? Your report will show the measured levels of different substances in your blood compared with normal reference ranges. Values outside these ranges may point to an infection, inflammation, anemia, a hormone imbalance, or another condition, but an abnormal result does not automatically mean you are seriously ill. Your healthcare provider will interpret the findings together with your symptoms, medical history, and other tests before discussing the next steps with you.

Results show the change in androstenedione levels from the baseline (before challenge) to 20 minutes after stimulation. A normal response shows a significant increase in androstenedione levels after stimulation. An abnormally low response may indicate adrenal insufficiency or impaired adrenal function. An excessively high response may suggest conditions like congenital adrenal hyperplasia, adrenal tumors, or polycystic ovary syndrome (PCOS). Your doctor will interpret your results in context with your symptoms and other test findings.

Are there any risks? Blood tests are very safe, but minor risks include slight pain or bruising at the needle site, brief dizziness, or light bleeding. Serious complications such as infection or excessive bleeding are rare. Applying gentle pressure and a cool cloth afterward usually eases any discomfort, and you should contact your provider if you notice swelling, warmth, or bleeding that does not stop.

The risks are minimal and similar to routine blood tests. You may experience slight pain or bruising at the injection site. Some people might feel dizzy or lightheaded during or after the blood draw. The stimulating hormone (ACTH) may cause temporary flushing, headache, or a fast heartbeat. Serious allergic reactions are rare. If you have a known allergy to ACTH or any components of the stimulation medication, inform your healthcare provider beforehand.