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Vitamin K effect in low birth weight infants
1Department of Pediatrics, Kumamoto University Medical School, Japan.
Insights
Low birth weight infants have lower levels of factor II coagulant antigen and coagulant activity. Vitamin K2 administration improved these levels, suggesting its prophylactic effectiveness in preventing hypoprothrombinemia.
Area of Science:
- Neonatal Medicine
- Hematology
- Biochemistry
Background:
- Low birth weight infants often exhibit impaired hemostasis.
- Vitamin K is crucial for the synthesis of coagulation factors, including Factor II.
Purpose of the Study:
- To investigate coagulation factor levels in low birth weight infants.
- To evaluate the efficacy of vitamin K2 in treating hypoprothrombinemia in this population.
Main Methods:
- Measurement of Factor II coagulant antigen (FII-AG), protein induced by vitamin K absence or antagonist II (PIVKA-II), and coagulant activity (normotest).
- Comparison between low birth weight infants and full-term infants.
- Group A infants received vitamin K2, while Group B did not.
Main Results:
- One-day-old low birth weight infants showed lower FII-AG and normotest levels than full-term infants.
- PIVKA-II levels became positive in 65.2% of untreated infants (Group B) within seven days.
- Vitamin K treatment led to greater normotest improvement in infants with positive PIVKA-II levels.
Conclusions:
- Hypoprothrombinemia in low birth weight infants is linked to reduced Factor II coagulant antigen synthesis.
- Prophylactic vitamin K administration is effective in improving coagulation parameters, likely by enhancing Factor II synthesis.
Abstract:
Factor II coagulant antigen (FII-AG), the protein induced by vitamin K absence or antagonist II (PIVKA-II), and coagulant activity (normotest) were measured in low birth weight infants. The factor II coagulant antigen and normotest levels in one-day-old babies were lower than those of full-term infants (P less than .005, P less than .01, respectively). Infants whose normotest levels were less than 30% at one day (group A) received vitamin K2, and the others whose normotest levels were greater than 30% at one day (group B) were not treated. At this time, the mean factor II coagulant antigen level was significantly lower in group A than in group B (P less than .05). During the first seven days of life, in 65.2% of the infants in group B the PIVKA-II level became positive, but this did not occur in any infant in group A. After vitamin K treatment, there was greater improvement in the normotest level in infants with positive PIVKA-II levels than in those with negative PIVKA-II levels. This observation indicates that the hypoprothrombinemia found in low birth weight infants at one day of age is attributable to reduced synthesis of factor II coagulant antigen in the liver at this stage, but the prophylactic administration of vitamin K seemed to be effective even in such infants, probably because of the increase in factor II coagulant antigen synthesis (P less than .001) during the first seven days of life.