Question

What is the importance of lab tests for patients with eating disorders? How reliable are the lab tests? What kind of predictors are they? What are the typical lab abnormalities in the anorexic patient?

Answer 1

• Laboratory testing plays a vital role in the detection, diagnosis and treatment of disease in patients. Laboratory tests help determine the presence, extent or absence of disease and monitor the effectiveness of treatment.  
• Laboratory test helps to detect the physical dangers of eating disorders such as malnutrition, dehydration, elctrolyte imbalance, vitamin and mineral defficiency etc. This will help the doctor to diagnose and treat the conditions in eating disorder patient before they lead to dangerous diseases or abnormal functioning in the patient.
• Lab tests are reliable because a doctor can not diagnose and detect only on basis of physical examination. For example, lab test such as - 1) Complete blood cell count (CBC) - The most common blood test performed by your doctor. This will check for things like low iron (anemia), infections, some cancers, arthritis and inflammations, and immune system functionality. The test does all this by checking white blood cell count, red blood cell count and platelets count. 2) Electrolytes - Dehydration, malnutrition, self-induced vomitting and laxative and/or diuretic abuse can all cause imbalances in the electrolytes. Electrolytes are a specific combination of minerals that our body needs to maintain balance over to function properly. Common symptoms are leg cramps, heart palpitations, high or low blood pressure and swelling in the legs and feet. An electrolyte imbalance can lead to kidney failure, heart attack and death.
• The typical lab abnormalities seen in anorexia nervosa are the following :

• CBC and ESR : The hemoglobin levels are typically normal, although elevations are observed in states of dehydration. If anemia is observed, it is not due to menstrual blood loss, as these patients are usually amenorrheic. The white blood cell (WBC) count is typically low due to increased margination, and thrombocytopenia is also observed. The ESR is normal in anorexia nervosa.

• Blood chemistry shows the following in anorexic patient : Hyponatremia , Hypokalemia, Hypoglycemia, Elevated blood urea nitrogen (BUN), Acidosis.

• Liver Function Studies : Liver function test results are minimally elevated, but levels encountered in patients with active hepatitis are not observed. Albumin and protein levels are usually normal, because although the amount of food intake is restricted, it usually contains high-quality proteins. A dramatic elevation in cholesterol is observed in cases of starvation and may be secondary to the following: (1) a decrease in triiodothyronine (T3) levels, (2) low cholesterol-binding globulin levels, and (3) leakage of intrahepatic cholesterol.

• Imaging Studies : A chest radiograph may reveal rib fractures or pneumomediastinum in the presence of other examination and laboratory findings to suggest repetitive vomiting. Patients may also show evidence of osteopenia. Radiographic evidence of emphysematous changes may be present on chest computed tomography (CT) scans of patients with anorexia nervosa.

• Echocardiography can reveal a decreased ventricular mass and mitral valve prolapse and can reveal evidence of sinus bradycardia, ST-segment elevation, T-wave flattening, low voltage, and rightward QRS axis, although these changes are clinically insignificant. A finding of QT-interval prolongation may indicate that the patient is at risk for cardiac arrhythmias and sudden death.