Sir.—Alkaline urine has traditionally been associated with Proteus urinary tract infections.1 In the absence of an infection, clinical findings might suggest other diagnoses, but these are rare in adolescents. The following are some of the traditional causes of alkaline urine2: (1) urinary tract infection (Proteus and others); (2) metabolic alkalosis (pyloric stenosis and others); (3) failure of acidification (renal tubular acidosis, chronic renal failure, or aldosterone abnormalities); (4) ingestion (salicylate, sodium bicarbonate, acetazolamide, etc); and (5) respiratory alkalosis (hyperventilation).
After noticing alkaline urine in a number of otherwise healthy patients with eating disorders, we prospectively examined urine pH in a hospital-based adolescent medicine practice to determine Urine pH (mean ± SE) in outpatients presenting to the adolescent medicine division. The difference between control subjects and patients with eating disorders was highly significant, at P<.001. ED indicates patients with eating disorders (n