The excretion of C6-C10-dicarboxylic acids in the urine of newborn infants during starvation. Evidence for omega-oxidation of fatty acids in the newborn.

The excretion of C6-C10-dicarboxylic acids, i.e. adipic, suberic and sebacic acids, was measured during the three first days of life in 3 fasting newborns, 2 newborns fed with isocaloric glucose and 2 newborns given mothers'-milk. On the second and third day of life the starved children excreted 27-84 mmol adipic acid/mol creatinine, 6-22 mmol suberic acid/mol creatinine and 4-7 mmol sebacic acid/mol creatinine. The excretion of C6-C10-dicarboxylic acids in the neonates given glucose or mothers'-milk was, for the first three days of life, 0-9 mmol adipic acid/mol creatinine, 0-10 mmol suberic acid/mol creatinine and 0-4 mmol sebacic acid/mol creatinine. The latter amounts are equivalent to the excretion of dicarboxylic acids in older children. It is argued that the detected dicarboxylic acids are formed by omega-oxidation of long-chain monocarboxylic acids followed by beta-oxidation, and that the excreted amounts reflect omega-oxidation activity. It is speculated that the substantial omega-oxidation activity in the starving newborn serve to provide succinyl-CoA-substrate for the citric acid cycle and for gluconeogenesis.