An Unusual Cause of Metabolic Alkalosis and Hypocalcemia in Childhood.

Abstract

An 8-year-old boy presented to the emergency department with complaints of intermittent stiffening of his upper and lower limbs. Shortly after his arrival he had a large volume (approximately 500 mL) of nonbilious projectile vomit. He described general weakness and fatigue the previous night and on waking, with no history of headaches, diarrhea, fevers, or other symptoms of infection. In the past 4 months he had experienced intermittent generalized abdominal pain, nausea, anorexia, vomiting, and mild weight loss (3 kg). He had presented 2 months earlier with vomiting. Investigations including a complete blood count, electrolytes, liver function tests, albumin-corrected calcium, magnesium, and phosphate were within reference intervals at that time. An abdominal ultrasonography was unremarkable. The episodes of vomiting had become increasingly more frequent and forceful. His past medical history was otherwise unremarkable. On presentation he was afebrile but tachycardic (pulse rate 156 bpm), tachypneic (respiratory rate 32/min), and mildly hypertensive (bp 125/78 mmHg). He was intermittently drowsy but easily rousable. He was described as having “locked hands and curled toes” consistent with carpopedal spasms and twitching movements of his tongue. He had no focal neurological signs, and his power and reflexes were essentially normal. There were no cardiac murmurs, and his respiratory examination was unremarkable. His abdomen was soft and nontender, with normal bowel sounds. Biochemical testing on presentation showed hypokalemia, hypochloremia, and hyperbicarbonatemia (Table 1). He had evidence of dehydration and prerenal azotemia (increased urea, creatinine, and urate) and normal total protein and albumin. His liver function tests, lipase, thyroid function tests, albumin-corrected calcium, phosphate, and magnesium were normal. An electrocardiogram revealed a prolonged corrected QT interval (QTc 480 ms). Despite the normal albumin-corrected calcium, the presence of carpopedal spasms and the …