According to Yahoo.com the following tests are taken to diagnose the eating disorder:

• Chem 20: Definition
  "Chem-20 is a "battery" of 20 chemical tests performed on serum (the portion of blood without cells). Electrolytes are ionized salts in blood or tissue fluids (ions are atoms or molecules that carry an electrical charge); electrolytes in the body include sodium, potassium, chlorine, and many others (see the Normal Values). The rest of the tests focus primarily on chemicals related to the body's metabolism and the breakdown of various substances. These would be tests that allow us to evaluate the function of the liver and kidney" http://health.yahoo.com/health/encyclopedia/003468/0.html
• Urinalysis Definition
  "A urinalysis is an examination of the urine by physical or chemical means. Urinalysis comprises a battery of chemical and microscopic tests that help to screen for urinary tract infections, renal disease, and diseases of other organs that result in abnormal metabolites (break-down products) appearing in the urine." http://health.yahoo.com/health/encyclopedia/003579/0.html
• an ECG  Definition
  "An electrocardiogram (ECG) is a test that records the electrical activity of the heart.ECG is used to measure the rate and regularity of heartbeats as well as the size and position of the chambers, the presence of any damage to the heart, and the effects of drugs or devices used to regulate the heart (such as a pacemaker)." http://health.yahoo.com/health/encyclopedia/003868/0.html