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Postheparin plasma lipoprotein and hepatic lipases in preterm neonates
Insights
Lipoprotein lipase activity in preterm infants is generally sufficient for fat clearance, except in cases of septic shock. This finding challenges previous assumptions about lipase function in premature neonates.
Area of Science:
- Biochemistry
- Neonatology
- Pediatric Metabolism
Background:
- Preterm infants exhibit slower fat clearance compared to term infants.
- This slower clearance has been historically attributed to low lipoprotein lipase activity.
Purpose of the Study:
- To investigate lipoprotein lipase and hepatic lipase activities in preterm infants.
- To determine the role of these lipases in fat clearance in preterm neonates, particularly in the context of septic shock.
Main Methods:
- Measured postheparin plasma lipoprotein lipase and hepatic lipase activities in 11 preterm infants (1-4 days old).
- Activities were assessed after a heparin bolus and during exchange transfusion.
- Infants were categorized into two groups: good clinical condition (group 1) and septic shock (group 2).
Main Results:
- Group 1 infants showed higher lipase activities than term infants.
- Group 2 infants had extremely low initial lipase activities, which increased during exchange transfusion.
- Lipoprotein lipase activity was not the primary cause of slow fat clearance in preterm infants, except in septic shock.
Conclusions:
- Preterm infants generally possess adequate lipoprotein lipase activity for fat metabolism.
- Septic shock significantly impairs lipase activity, leading to impaired fat clearance in preterm neonates.
- Findings suggest a re-evaluation of the causes of delayed fat clearance in preterm infants, excluding lipase deficiency in most cases.
Abstract:
Postheparin plasma lipoprotein lipase and hepatic lipase activities of 11 preterm infants aged 1 to 4 days were measured 15 min after a heparin bolus of 100 IU/kg and during an exchange transfusion performed with fresh heparinized blood. Each infant had a birth weight (range, 1210-3490 g) appropriate for gestational age (range, 28-36 (wk). Eight of the infants (group 1) were in good clinical condition while three (group 2) suffered from septic shock. After the heparin bolus and during the exchange transfusion, lipoprotein and hepatic lipase activities in group 1 were higher than in term infants. In group 2, both lipase activities were extremely low after the heparin bolus but increased approaching the activities of group 1 during the exchange transfusion. Clearance of fat from the circulation is slower in preterm than term infants. This has been attributed to low lipoprotein lipase activity. Our results, however, indicate that lipoprotein lipase is not the reason for slow clearance of fat from the circulation in preterm infants except in septic shock.