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Protein S in the first year of life
D Sthoeger1, M Nardi, M Karpatkin
1Department of Pediatrics, New York University Medical Center, New York 10016.
Insights
This study establishes normal levels for total protein S, free protein S, and C4b binding protein in infants. Free protein S reaches adult levels within 4 months due to low C4b binding protein at birth.
Area of Science:
- Biochemistry
- Pediatric Hematology
- Neonatal Physiology
Background:
- Protein S is a crucial vitamin K-dependent anticoagulant protein.
- Its activity is regulated by C4b-binding protein (C4bBP).
- Understanding neonatal levels is vital for assessing thrombotic risk.
Purpose of the Study:
- To determine normal ranges for total protein S, free protein S, and C4bBP in healthy term infants.
- To track the postnatal development of these protein levels throughout the first year of life.
Main Methods:
- Quantitative measurement of total protein S, free protein S, and C4bBP.
- Analysis of samples from healthy term infants at various time points from birth to 12 months.
- Comparison of infant levels to adult mean values.
Main Results:
- Total protein S increased from 36.5% of adult mean at day 1 to 90% by 6-12 months.
- Free protein S was 54.2% of adult mean at day 1, reaching adult range by 2 months and adult mean by 4 months.
- Low C4bBP levels (28.8% of adult mean) at birth and a slow postnatal rise contributed to high free protein S.
Conclusions:
- Infants exhibit distinct developmental patterns for protein S and C4bBP levels.
- The early postnatal period is characterized by relatively high free protein S levels.
- These findings provide essential reference ranges for neonatal coagulation studies.
Abstract:
Total protein S, free protein S and C4b binding protein were measured in healthy term infants in order to establish the normal levels of these proteins during the first year of life. Total protein S rose from 36.5% of the adult mean level on day 1 of life to 90% between 6 and 12 months of age. Free protein S was 54.2% of the adult mean on day 1 of life, all values were in the adult range by 2 months and the mean value was no different from the adult at 4 months. This relatively high level of free and presumably active protein S reflects low levels of C4bBP at birth (28.8% of the adult mean) and a slow postnatal rise.