Internal medicine is the branch of medical science that combines laboratory science along with care of patients. The specialists focus on diagnosis, treatment and prevention of adult diseases.

Doctors who practice this branch are called internists. They are especially trained to resolve confusing diagnostic disorders involving more than one disease at a time. Internal medicine sub specialists can also practice general internal medicine though they usually concentrate on their own unique subspecialty like pulmonology concerning lungs, endocrinology concerning endocrine system, hematology concerning blood, cardiology concerning heart etc. They may also specialize in immunology and allergy.

The principle tools for diagnosis are physical examination of patients and medical history. Apart from taking cue from visible signs and symptoms doctors also take help of medical imaging, electrolyte count, X-ray, renal function test and blood tests. They can also be used as effective tools for screening, primarily for older patients as in tests like full blood count and blood urea nitrogen. There are some specific tests for particular diseases like biopsy for cancer.

Internal medicine though mainly focuses on study and cure with medication but many non-surgical treatments are also used by some subspecialties. For example cardiology uses angioplasty, cardioversion. gastroenterology uses endoscopy and ERCP, and nephrology relies heavily on dialysis.