Complete Blood Count (CBC): What This Blood Test Measures and When Your Doctor May Order It

A complete blood count (CBC) is one of the most common blood tests. It measures the different cells that make up your blood, including red blood cells, white blood cells, hemoglobin, hematocrit, and platelets. These measurements give your health care team a broad picture of your overall health and can help detect conditions such as anemia, infections, and certain blood disorders, often before symptoms appear.

The androstenedione test measures the amount of androstenedione in your blood. Androstenedione is a steroid hormone produced primarily by the adrenal glands in both men and women, and by the ovaries in women. It serves as a precursor to other hormones, including testosterone and estrogen. This test helps healthcare providers assess how well your endocrine system is functioning and can aid in diagnosing various hormonal disorders.

Your doctor may order a CBC as part of a routine checkup, before surgery, or to help evaluate symptoms such as fatigue, weakness, fever, frequent bruising, or unexplained bleeding. It is also used to monitor an ongoing condition, such as kidney disease, or to check how treatments like chemotherapy or certain long-term medications are affecting your blood cells over time.

Your doctor may order an androstenedione test if you are experiencing symptoms of hormone imbalance. In women, this may include irregular periods, excessive hair growth (hirsutism), acne, or signs of polycystic ovary syndrome (PCOS). In men, it may help evaluate early or delayed puberty. The test can also help detect adrenal gland disorders, such as congenital adrenal hyperplasia, adrenal tumors, or ovarian tumors that produce excess hormones.

Preparation for a CBC is usually very simple. You can normally eat and drink as usual unless your provider asks you to fast because other blood tests are being done at the same time. Tell your care team about all medicines, vitamins, and supplements you take, since some can influence your results. Being well hydrated before your appointment can also make your veins easier to find.

Your healthcare provider may ask you to fast for 8-12 hours before the blood draw. Certain medications, including birth control pills, corticosteroids, and hormone supplements, can affect test results. Inform your doctor about all medications and supplements you are taking. The test is typically performed in the morning, as hormone levels naturally fluctuate throughout the day and are usually highest in the morning hours.

During the test, a nurse or phlebotomist will clean a small area of skin on your arm, usually the inside of the elbow, with an antiseptic and wrap a band around your upper arm. A thin needle is inserted into a vein and a small sample of blood is collected into a tube. You may feel a brief sting or pinch, but the draw typically takes only a few minutes, and a small bandage is placed on the site afterward.

A healthcare professional will clean the injection site with alcohol and insert a needle into a vein, usually in your arm. You may feel a brief pinch or sting. The blood will be collected into a vial, and the needle will be removed. The process typically takes less than five minutes. After the test, you may have minor bruising or soreness at the injection site, which usually resolves quickly.

Your report will show each result alongside a normal reference range, often given in cells per microliter (µL). Values that are higher or lower than the range can suggest conditions such as anemia, infection, inflammation, or clotting problems, but a single abnormal number does not always mean you are sick. Your provider will interpret your results together with your symptoms, history, and other tests, so ask what they mean for you and whether follow-up is needed.

Normal androstenedione levels vary based on age, sex, and the laboratory that performs the test. Generally, adult female levels range from 0.7 to 2.6 ng/mL, while adult male levels range from 0.6 to 2.0 ng/mL. Your results will be interpreted in the context of your symptoms, medical history, and other test results. Abnormal levels do not necessarily indicate a serious condition but warrant further investigation by your healthcare provider.