A complete blood count (CBC) is a blood test used to evaluate your overall health and detect a wide range of disorders, including anemia, infection and leukemia.
A complete blood count test measures several components and features of your blood, including:
- Red blood cells, which carry oxygen
- White blood cells, which fight infection
- Hemoglobin, the oxygen-carrying protein in red blood cells
- Hematocrit, the proportion of red blood cells to the fluid component, or plasma, in your blood
- Platelets, which help with blood clotting
Abnormal increases or decreases in cell counts as revealed in a complete blood count may indicate that you have an underlying medical condition that calls for further evaluation
CMP
How is it used?
The comprehensive metabolic panel (CMP) is used as a broad screening tool to evaluate organ function and check for conditions such as diabetes, liver disease, and kidney disease. The CMP may also be ordered to monitor known conditions, such as hypertension, and to monitor people taking specific medications for any kidney- or liver-related side effects. If a health practitioner is interested in following two or more individual CMP components, he or she may order the entire CMP because it offers more information.
When is it ordered?
The CMP is routinely ordered as part of a blood work-up for a medical exam or yearly physical. While the individual tests are sensitive, they do not usually tell a health practitioner specifically what is wrong. Abnormal test results or groups of test results are usually followed up with other specific tests to confirm or rule out a suspected diagnosis.
Thyroid-Stimulating Hormone (TSH)
A thyroid-stimulating hormone (TSH) blood test is used to check for thyroid gland 
problems. TSH is produced when the hypothalamus releases a substance called thyrotropin-releasing hormone (TRH). TRH then triggers the pituitary gland to release TSH.
TSH causes the thyroid gland to make two hormones: triiodothyronine (T3) and thyroxine (T4). T3 and T4 help control your body's metabolism.
Triiodothyronine (T3) and thyroxine (T4) are needed for normal growth of the brain, especially during the first 3 years of life. A baby whose thyroid gland does not make enough thyroid hormone (congenital hypothyroidism) may, in severe cases, be mentally retarded. Older children also need thyroid hormones to grow and develop normally.
This test may be done at the same time as tests to measure T3 and T4.
Why It Is Done
A test for thyroid-stimulating hormone (TSH) is done to:
- Find out whether the thyroid gland is working properly.
- An underactive thyroid gland (hypothyroidism) can cause symptoms such as weight gain, tiredness, dry skin, constipation, a feeling of being too cold, or frequent menstrual periods.
- An overactive thyroid (hyperthyroidism) can cause symptoms such as weight loss, rapid heart rate, nervousness, diarrhea, a feeling of being too hot, or irregular menstrual periods.
- Find the cause of an underactive thyroid gland (hypothyroidism). TSH levels can help determine whether hypothyroidism is due to a damaged thyroid gland or some other cause (such as a problem with the pituitary gland or the hypothalamus).
- Keep track of treatment with thyroid replacement medicine for people who have hypothyroidism.
- Keep track of thyroid gland function in people who are being treated for hyperthyroidism. This treatment may include antithyroid medicine, surgery, or radiation therapy.
- Double-check the diagnosis of an underactive thyroid gland in a newborn (congenital hypothyroidism).
