Sir.—Paxson and co-workers' article (Am J Dis Child 131:139, 1977) prompts us to report osmolalities and renal solute load in infant formulas commercially available in Japan.
All of them are powdered formulas and reconstructed with water as
directed by the manufacturer, Osmolality and mineral and nitrogen contents of each reconstructed product were measured at two different laboratories. The osmolality was determined by freezing-point depression method with an osmometer. Sodium and potassium were measured with a flame photometer. Chloride was measured by the Volhard back titration procedure. Nitrogen was measured by the Kjeldahl method. Renal solute load of each formula (mOsm/liter) was calculated as follows: the sum of milliequivalents of sodium, potassium and chloride plus 4 mOsm of urea per gram of protein in a liter of formula.1 Results obtained in both laboratories were quite similar, and the mean of these are listed in the Table. The Committee on
MATSUDA I, KAMIMURA M, OKA Y, ARASHIMA S. Osmolalities of Infant Formulas in Japan. Am J Dis Child. 1977;131(12):1403. doi:10.1001/archpedi.1977.02120250085014