Fetal osteocalcin levels are related to placental 11 beta-hydroxysteroid dehydrogenase activity in humans.

OBJECTIVE

Overexposure to glucocorticoids in utero reduces birth weight and, in animals, leads to persistent hypertension in the offspring. The fetus is normally protected from maternal glucocorticoids by placental 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD) which catalyses the conversion of cortisol to inert cortisone. In adult humans, osteocalcin is a sensitive marker of glucocorticoid exposure. The aim of this study was to determine whether cord blood osteocalcin levels were related to the ability of placental 11 beta-HSD to inactivate maternal cortisol.

DESIGN

Cross-sectional study examining the relation between cord blood levels of osteocalcin and placental glucocorticoid metabolism at term.

PATIENTS

Twenty-one women attending for delivery at the Simpson Memorial Maternity Pavilion in Edinburgh had cord venous and arterial blood samples collected at delivery.

MEASUREMENTS

Cord plasma levels of osteocalcin, cortisol and cortisone were measured by radioimmunoassay and indices of placental 11 beta-HSD activity were calculated.

RESULTS

All indices of placental 11 beta-hydroxysteroid dehydrogenase activity correlated directly and significantly with cord blood osteocalcin levels. For cord blood osteocalcin and the placental 11 beta-HSD Activity Index, Pearson's r was +0.58, r2 = 0.33 and P < 0.02.

CONCLUSION

We conclude that term cord blood osteocalcin level reflects the effectiveness of placental glucocorticoid inactivation, and may be a marker for the development of adult hypertension.