This test looks for specific gene changes in a sample of your blood. These gene changes cause most cases of Tay-Sachs disease.

This test checks for proteins in the cerebrospinal fluid to help healthcare providers diagnose Alzheimer disease.

This test looks for a substance that can appear in your blood if you have hairy cell leukemia.

This test measures the level of the hormone thyroxine (T4) in your blood. This test can show whether your thyroid gland is overactive (hyperthyroidism) or underactive (hypothyroidism).

This test finds and counts 3 types of white blood cells in your blood. White blood cells help your body fight off infections and illness.

This test looks for antibodies that your body made when fighting off group A Streptococcus bacteria. These bacteria cause strep throat.

This test looks for white blood cells in your stool. This can help your doctor figure out what's causing inflammatory diarrhea.

This test looks for bacteria, viruses, and other organisms in your stool. This test can help find out what's causing a digestive tract infection.

This test finds out what's causing your lung infection. Sputum, or phlegm, is the mucus that settles in the lower airways of your lungs when you have an infection or a chronic illness.

This test measures the amount of sodium, or salt, in your urine. This test can help your doctor find out whether you have too much salt in your diet.