Which of the following would you expect to be elevated in a patient with anorexia nervosa?
Most blood results in anorexia are low except for growth hormone, cholesterol and cortisol.
Cholesterol levels are frequently raised in patients with anorexia. This usually resolves when intake increases and should not be treated with statins.Eating disorders - metabolic complications
Blood abnormalities are a major cause of morbidity and mortality in patients with eating disorders. Important changes in blood chemistry are listed below (Winston 2012):-
Electrolytes
Hypokalemia (low potassium)
Hypomagnesemia
Hypocalcemia
Hypophosphatemia (note in bulimia a high phosphate level is generally seen)
Endocrine
Low estradiol
Low luteinizing hormone (LH)
Low follicular stimulating hormone (FSH)
Low T3 (low T3 syndrome/ sick euthyroid syndrome), TSH and T4 are usually normal
Hypercortisolism
Hypoglycemia
Elevated growth hormone
Others
Hypercarotenemia
Hypercholesterolemia
Urea and creatinine low
Winston (2012) The clinical biochemistry of anorexia nervosa. Ann Clin Biochem March 2012 vol. 49 no. 2 132-143.
The following table gives a useful guide to the complications of purging (the effects vary depending on what laxative and diuretic is used so it's not that straightforward):
| Sodium (serum) | Potassium (serum) | Chloride (serum) | PH (serum) | |
|---|---|---|---|---|
| Vomiting | Increased, decreased, or normal | Decreased | Decreased | Increased |
| Laxatives | Increased or normal | Decreased | Increased or decreased | Increased or decreased |
| Diuretics | Decreased or normal | Decreased | Decreased | Increased |
Mehler (2003). Bulimia nervosa. N Engl J Med ;349:876.
Be aware that most patients who purge do not develop electrolyte abnormalities so screening is not indicated.
