title: Late metabolic acidosis: a reassessment of the definition.
abstract: The term "late metabolic acidosis" is generally used to define a population of apparently healthy LBW infants who fail to grow and have a base deficit in excess of 5 mEq/l (CO2TOT less than 21 mM). A relationship between hypobasemia and the lack of appropriate growth was postulated. This conclusion was reached, however, in the absence of adequate information regarding the distribution of acid-base variables in healthy LBW infants. The results of this study demonstrate that the CO2TOT of LBW infants (n = 114) rises between birth and three weeks of life from a mean of 18.6 to 20.3 mM. The frequency distribution of CO2TOT values did not show any significant deviations from normality, and 2 SD included values as low as 14.5 mM. No difference in the rate of growth was detected between "hypobasemic" infants given a solution of bicarbonate calculated to bring their blood CO2TOT to greater than 21 mM and those given similar amounts of isotonic saline solution. The ability of the LBW infants to excrete an ammonium chloride load was not related to their acid-base status and was comparable to that of term infants. It is apparent that the definition of late metabolic acidosis needs to be reconsidered.
mesh_terms: D000138:Acidosis / Q000453:epidemiology*; D001835:Body Weight; D002245:Carbon Dioxide / Q000097:blood; D005069:Evaluation Studies as Topic; D006128:Growth; D006801:Humans; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D007235:Infant, Premature, Diseases / Q000453:epidemiology*
chemical_list: D002245:Carbon Dioxide