Plasma cortisol, cortisone and urinary glucocorticoid metabolites in preterm infants.
OBJECTIVE
In the fetal circulation, there is a low cortisol:cortisone (F:E) ratio ( approximately 0.3) suggesting high activity of 11beta-hydroxysteroid dehydrogenase type 2 (11betaHSD2). The circulating F:E ratio rises after birth in term infants, but little is known about infants born prematurely. Our hypothesis was that the low fetal plasma F:E ratio would persist in infants born prematurely, due to persistently high tissue 11betaHSD2 activity. To test this hypothesis, a longitudinal observational study of plasma F, E levels and urinary F and E metabolites was performed in 22 preterm infants of 24-31 weeks gestation.


RESULTS
Median plasma F was 234-380 nmol l(-1), median 124-177 nmol l(-1) from 1 to 14 days age. Plasma F fell with increasing postnatal and postconceptional age. The F:E ratio was 3 in the first week of life, and thereafter was 1-2, falling with postnatal age. Urinary glucocorticoid metabolites were low in quantity ( approximately 48-120 microg kg(-1) day(-1)), consisted of E metabolites until term, and did not reflect the plasma F:E ratio.


CONCLUSIONS
The fetal plasma F:E ratio did not persist in these preterm infants, due to tenfold higher levels of F. The F:E ratios were similar to those reported in term infants. These data suggest that the low F:E ratio in utero is due to low fetal production of cortisol, and effective placental inactivation of maternal F by 11betaHSD2.
Midgley
P C
PC
Neonatal Unit, University College and Middlesex Hospital Medical School, London, UK. paula.midgley@ed.ac.uk
Holownia
P
P
Smith
J
J
Moore
M
M
Russell
K
K
Oates
N
N
Shaw
J C
JC
Honour
J W
JW
D000375:Aging / Q000097:blood / Q000652:urine; D003348:Cortisone / Q000097:blood*; D005260:Female; D005938:Glucocorticoids / Q000378:metabolism / Q000652:urine*; D006801:Humans; D006854:Hydrocortisone / Q000097:blood*; D007231:Infant, Newborn; D007234:Infant, Premature / Q000097:blood* / Q000254:growth & development / Q000652:urine*; D008297:Male; D013256:Steroids / Q000097:blood / Q000652:urine
D005938:Glucocorticoids; D013256:Steroids; D003348:Cortisone; D006854:Hydrocortisone