SEX STEROID BINDING PROTEIN (SBP) IN PREMATURE INFANTS

Abstract

We have recently reported that SBP is measurable in amniotic fuid: low levels with no sex difference, but showing a significant (p=0.02) correlation (r=0.587) with gestational age (GA). This prompted us to examine whether the postnatal pattern was different between premature and full-term infants. SBP was measured by a solid phase method in 102 plasma samples from healthy premature babies (28 to 38 weeks'GA) and in 290 samples from full-terms infants matched for age (0 to 280 days). There was no sex difference at any age. Results from boys and girls were pooled and are given in μg/l of plasma. In the cord, a positive correlation between SBP and GA (r=0.42; p<0.01) was found. In peripheral blood, SBP was lower (p=0.02) in premature (4.9 ±1.9) than in full-term (7.1 ±3.3) infants 0-2 days old. A postnatal 3-4 fold rise was observed in both groups, with a significant correlation with age from day 0 to 30 (full-terms: r=0.723; n = 120) (prematures: r=0.657; n = 66) . The rise lagged somewhat behind in prematures, whose levels were still significantly lower (9.8 ± 4.9) than in full-terms (15.0 ±5.7) the 2nd week of life. Thereafter, SBP levels were not different in the successive age groups. In conclusion: 1) At birth, plasma SBP is lower in premature than in full-term infants. 2) A postnatal rise occurs in both, and by the third week of life values are similar. 3) Factors controlling the postnatal rise of SBP are poorly understood. Sex steroids do not play a role, since SBP rises dramatically at times when plasma estradiol drops and plasma testosterone rises in males infants. Whatever the factor(s) responsible, it is not related to prematurity.

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