Influence of protein intake and liver function on acid base balance in premature infants.

In 43 patients with late metabolic acidosis (LMA) the factors promoting LMA were investigated. Postnatal adaptation was distributed in all cases, in 35 patients acidosis developed after introduction of formula feeding. Whereas no differences were observed in renal function (urine volume and renal molar excretion) between acidotic and non-acidotic patients, there was a significantly higher concentration of bile acids in serum (26.1 +/- 9.6 vs 98.6 +/- 21.6 mumol/l), a significantly increased fractional volume of stools (8.2 +/- 1.3 vs 11.4 +/- 1.9% of intake, and higher faecal fat excretion (26.5 +/- 5.2 vs 39.1 +/- 6.6% of faecal weight) in LMA patients than non-acidotic formula-fed infants. It is suggested that impaired postnatal development of liver function caused by severe disturbances of postnatal adaptation (respiratory distress, persistent fetal circulation, sepsis) is one of the most important factors in the pathogenesis of LMA. Thus, liver function should be checked before a protein intake surpassing that of a breastfed infant is introduced. Concentration of the serum bile acid level seems a reliable marker of LMA.