The significance of alkalosis and hypochloremia in hypertrophic pyloric stenosis.

Hypochloremic alkalosis is the "classical" electrolyte abnormality seen in hypertrophic pyloric stenosis (HPS), yet it occurs in only about half the patients. To define the clinical differences between infants who were alkalotic or hypochloremic and those who were not, we reviewed the records of 216 patients treated for HPS over a recent 5-year period at our institution. The 202 patients who had a full set of serum electrolytes drawn on admission were divided into nonalkalotic and alkalotic bicarbonate groups A (less than or equal to 25 mEq/L, n = 105) and B (greater than 25 mEq/L, n = 97) and also nonhypochloremic and hypochloremic chloride groups A (greater than or equal to 99 mEq/L, n = 117) and B (less than 99 mEq/L, n = 85). The alkalotic group B had a significantly higher proportion of black patients (17.5% v 8%), longer mean duration of illness (17.8 v 9.4 days), higher incidence of palpable pyloric mass (97% v 82%), greater degree of dehydration, lower mean serum sodium (136.3 v 137.7 mEq/L), lower mean serum potassium (4.50 v 5.15 mEq/L), and lower mean serum chloride (92.4 v 102.3 mEq/L) than did the nonalkalotic group A.(ABSTRACT TRUNCATED AT 250 WORDS)