Anorexia nervosa (AN) has serious negative effects on multiple organs and systems of the human body. As patients often do not make their eating disorder the subject of discussion, the physician is forced to rely on the physical examination and laboratory parameters as diagnostic hints. Obvious signs of AN are a body mass index (BMI) below 17.5 kg/m, dry and scaly skin, lanugo, edema, acrocyanosis, petechias, dental problems, and low blood pressure. However, because the often complex laboratory alterations can be difficult for the general psychiatrist to interpret, this article presents some useful guidelines. The plasma of patients with AN often shows alterations in laboratory parameters and appetite regulators, including electrolytes, liver enzymes, leukocyte count, hemoglobin (Hb), leptin, neuropeptide Y (NPY), triiodothyronine (T3), follicle-stimulating hormone (FSH), luteinizing hormone (LH), estrogen, ghrelin, pancreatic polypeptide (PP), tumor necrosis factor-alpha (TNF-alpha), and cortisol. Medical problems secondary to AN or due to the treatment itself may lead to further laboratory abnormalities. To date, despite these associated laboratory alterations, the diagnosis of anorexia is a clinical one, based on weight and specific psychopathology.
