Arriving at a diagnosis is a complicated process that involves many factors. It generally starts with a medical practitioner taking a detailed history of current symptoms, past illnesses and surgeries, exercise habits, smoking, drug and alcohol use, diseases of family members and any other symptoms. A physical exam is then performed as it relates to the symptoms. If warranted, the doctor may schedule diagnostic tests or assays to help find or confirm the diagnosis. Some of these tests are more common than others.
Blood Tests
Blood tests are commonly performed to screen for certain conditions. Three of the more common blood tests are a CBC, a BMP and a coagulation panel. The CBC, or complete blood count, measures levels of red blood cells, white blood cells and platelets. The BMP, or basic metabolic panel, measures levels of common chemicals in the blood, such as the electrolytes sodium and potassium. The coagulation panel helps determine how well the blood clots. If a particular condition is suspected, other tests can be performed, such as one that measures thyroid hormone if a thyroid disorder is possible, or one that measures fats and cholesterol to evaluate the need for cholesterol drugs.
Imaging
Various imaging tests are commonly used to establish a diagnosis. X-ray machines use small doses of radiation to see through soft tissues. Computed tomography, or CT, scans are similar to X-rays, but they synthesize many X-ray pictures together to get a very detailed view of the body. Ultrasound uses the echoing of sound waves bounced through the tissues to create an image. MRI, or magnetic resonance imaging, uses magnetic fields to create extremely detailed images.
Tissue Tests
Sometimes chemical tests or images are not enough to establish a diagnosis. If a lesion or diseased portion of the body is present, it may need to be biopsied. A biopsy takes a small tissue sample out for studies such as marking the tissue with dyes or markers for certain proteins and looking at it under a microscope. For example, if a stomach ulcer is not healing, a physician may insert a long, flexible tube called an endoscope through the mouth and into the stomach to look at the ulcer and remove a small piece of it for further study.
References
- National Institutes of Health: National Heart Lung and Blood Institute: Common Blood Tests
- "Encyclopedia of Diagnostic Imaging"; Baert, Albert; 2008
- Mayo Clinic: Biopsy: Types of biopsy procedures used to diagnose cancer
