Comparison of serum cortisol concentrations in preterm infants with or without late-onset circulatory collapse due to adrenal insufficiency of prematurity.

A recent survey found that approximately 4% of very low birth weight infants in Japan were treated with glucocorticoids postnatally for circulatory collapse thought to be caused by late-onset adrenal insufficiency. We identified 11 preterm infants with clinical signs compatible with this diagnosis (hypotension, oliguria, hyponatremia, lung edema, and increased demand for oxygen treatment) and matched them for gestational age with 11 infants without such signs. Blood samples were obtained for cortisol and its precursors from the patient group before the administration of hydrocortisone, and from the control group during the same postnatal week. All samples were analyzed using a gas chromatography-mass spectrometry system. Cortisol concentrations did not differ between the two groups (6.6 +/- 4.5 vs 3.4 +/- 2.7 microg/dL); however, the total concentration of precursors in the pathway to cortisol production was significantly higher in the patient group (72.2 +/- 50.3 vs 25.0 +/- 28.5 microg/dL; p < 0.05). We conclude that the clinical picture of late-onset adrenal insufficiency in preterm infants is not a result of an absolute deficiency of cortisol production, but may be a result of a limited ability to synthesize sufficient cortisol for the degree of clinical stress.

Development of an enzyme-linked immunosorbent assay for serum 11-dehydrocorticosterone in rat and mouse.

We have developed an enzyme-linked immunosorbent assay (ELISA) for serum 11-dehydrocorticosterone (4-pregnen-21-ol-3,11,20-trione). The antiserum against 11-dehydrocorticosterone 21-hemisuccinate-conjugated bovine serum albumin was raised in rabbits. As an enzyme-labeled antigen, 11-dehydrocorticosterone 21-hemisuccinate was conjugated to horseradish peroxidase. Two ELISA systems were established: one without the extraction of steroids from serum (direct method), and another that used an HPLC purification step (HPLC method). The cross-reactivity of all steroids tested against the antibody was low except cortisone (92%); however, since cortisone levels in rats and mice are negligible, cortisone does not interfere with this direct ELISA. The measurable range of serum 11-dehydrocortiocosterone in both the direct and HPLC methods was 0.3-250 ng/ml and 0.78-400 ng/ml, respectively. Both methods displayed satisfactory parallel dilution, recovery and reproducibility; moreover, the values obtained with each method significantly correlated with the alternate method. To evaluate the two ELISA systems, the serum concentrations of 11-dehydrocorticosterone in normal rats and mice were determined by these two systems. The levels in Wistar rats fluctuated from 3 to 14 weeks of age (7.8+/-2.6 ng/ml) but at 1 week (1.7+/-1.2 ng/ml) were significantly low compared to other ages. No sex differences were found in rats and mice. Further, using the proposed direct method, chronological changes of rat serum 11-dehydrocorticosterone levels after 11-dehydrocorticosterone administration have been investigated together with corticosterone levels. These results verify that the proposed ELISA for 11-dehydrocorticosterone is useful for measuring 11beta-HSD activities in combination with the determination of serum corticosterone in rats and mice.