Amniotic fluid cortisol as an index of fetal lung maturity

Amniotic fluid cortisol concentration was compared with lecithin/sphingomyelin ratio, gestational age, and eventual birth-weight in a large series of normal and high-risk human pregnancies in an effort to determine whether cortisol could be used as a reliable indicator of fetal maturity. It appears that when used alone amniotic fluid cortisol is of limited clinical value as an antepartum predictor of fetal respiratory status because of unacceptable percentages of false positive and false negative predictions. Whether amniotic fluid cortisol can be used as an adjunct in the evaluation of high-risk pregnancies with "transitional" L/S ratios remains to be explored.

Amniotic fluid cortisol in high-risk human pregnancies

Amniotic fluid cortisol (AFC) levels were measured in 76 normal and 67 high-risk human pregnancies. When compared to normal gestations, diabetic pregnancies were found to be associated with lower AFC levels, while toxemic, early Rh-sensitized, and other stressed pregnancies had higher mean cortisol values. Serially followed normal and high-risk pregnancies showed a progressive rise in AFC with increasing gestational age. Significant correlation between AFC concentrations and lecithin/sphingomyelin (L/S) ratios was noted in normal, diabetic, and toxemic gestations. These results are concordant with the hypothesis that cortisol may be involved in fetal lung development.

False elevation of plasma cortisol in congenital adrenal hyperplasia

Plasma cortisol values in seven patients with the 21-hydroxylase variant of CAH ranged from 9 to 35 micron/100 ml. (mean+/-S.E.=22+/-4) as determined fluorimetrically and from 22 to 35 microng/100 ml. (26+/-2) by competitive protein-binding radioassay. In these same patients the cortisol values obtained after Sephadex LH-20 column chromatography were much lower, ranging from 1 to 12.5 microng/100 ml. (5+/-2, p less than 0.01). In six normal subjects, cortisol values were similar before and after chromatography. Plasma concentrations of progesterone, 17alpha-hydroxyprogesterone, and 21-deoxycortisol in the CAH patients were increased 10 to 100-fold. The elevated cortisol values determined by customary methods were shown to be due to cross-interference of these and other steroids in the assays. Plasma cortisol values obtained routinely are falsely elevated and therefore misleading as a gauge of adrenal insufficiency in CAH.

The role of 11-deoxycorticosterone in human hypertension

1. Using a newly developed and validated radioassay method, we have measured plasma 11-deoxycorticosterone concentrations in a wide spectrum of human hypertensive states. 2. Patients with essential and renovascular hypertension have normal plasma concentrations of 11-deoxycorticosterone. 3. Elevated concentrations are seen in some patients with primary aldosteronism, Cushing's syndrome, low-renin hypertension, and in adult hypertensive subjects with elevated urinary 17-ketosteroid excretion. 4. An aetiological role for deoxycorticosterone in certain forms of human hypertension appears likely.

Unconjugated cortisol in human amniotic fluid: relationship to lecithin/sphingomyelin ratio

A specific and thoroughly validated competitive protein binding radioassay has been developed for the measurement of unconjugated cortisol in human amniotic fluid. Cortisol levels rose throughout normal gestation from 8.6 +/- 0.8 ng/ml at less than 20 weeks to 19.8 +/- 1.5 ng/ml at 30-40 weeks. Levels were significantly higher in amniotic fluid samples having mature lecithin/sphingomyelin (L/S) ratios (greater than 2), and good correlation with individual cortisol values was obtained (r = 0.79; P less than 0.001). These results support the hypothesis that cortisol plays a role in fetal lung maturation.

Interference of spironolactone in 11-doexycorticosterone radioassays

Uniformly elevated plasma 11-deoxycorticosterone (DOC) values are obtained in patients receiving spironolactone. This elevation is shown to be spurious, and is a result of cross-interference of spironolactine and its metabolite, canrenone, in both the DOC radioimmunoassay and competitive protein-binding radioassay.

The contribution of the zona fasciculata and glomerulosa to plasma 11-deoxycorticosterone levels in man

Using a newly developed radioassay method, plasma 11-deoxycorticosterone (DOC) levels were studied in 6 human volunteers for diurnal variation and for response to ACTH, metyrapone, dexamethasone, and low or high dietary sodium. DOC reached its peak of 6.4 +/- 1.2 ng/100 ml at 8:00 AM, and its nadir of less than 1 ng/100 ml at midnight. Corresponding plasma cortisol values were 14.1 +/- 1.4 mug/100 ml and 5.9 +/- 1.3 mug/100 ml respectively. After intramuscular ACTH (Cortrosyn 0.25 mg), DOC rose to 28.7 +/- 1.8 ng/100 ml in 1 h. Dexamethasone treatment for 3 days reduced DOC to less than 1 ng/100 ml in all 6 subjects. Oral metyrapone for 24 h resulted in dramatically elevated DOC levels of 1568 +/- 183 ng/100 ml. High dietary sodium did not affect DOC levels which averaged 5.6 +/- 0.7 ng/100 ml. After 3 days of sodium restriction, DOC levels were unchanged at 4.8 +/- 0.5 ng/100 ml (P greater than 0.9) despite high plasma renin activity and elevated plasma and urinary aldosterone. Dexamethasone was then added, and the diet continued for a further 2 days. In contrast to the effect of dexamethasone during ad lib sodium intake, DOC was not suppressed but slightly elevated to 8.6 +/- 1.4 ng/100 ml (P = 0.01), whereas plasma aldosterone decreased from 32.9 +/- 1.5 to 22.1 +/- 2.1 ng/100 ml. Seven additional subjects underwent the same diet for 5 days without the addition of dexamethasone. There was no change in their DOC values. It is concluded that the zona fasciculata is the main source of DOC, but in the presence of dexamethasone a contribution from the zona glomerulosa during sodium depletion is uncovered.

A competitive protein binding radioassay for deoxycorticosterone in human plasma

A simple, sensitive and reliable competitive protein binding radioassay using dog transcortin has been developed for the measurement of 11-deoxycorticosterone (DOC) in human plasma. A 1% plasma solution from dexamethasone treated male dogs served as the source of the binding protein. Sephadex LH-20 column chromatography was used for the separation of the steroid prior to assay. The method is sensitive enough to detect 50 pg of DOC. The intra- and interassay co-efficients of variation were 11.5% and 11.3% respectively. Water blanks and plasma blanks from adrenalectomized rats and humans gave negligible readings for DOC. Support for the identity of the steroid being assayed as DOC was obtained by subjecting a plasma pool to multiple radioassays using 4 different binding proteins including 2 anti-DOC antibodies. The values obtained in all 4 systems were in good agreement confirming the fact that DOC was the steroid being measured. Morning plasma DOC levels measured in 29 healthy subjects averaged 8.0 plus or minus 1.2 (S.E.) ng% in 14 males, and 8.7 plus or minus 0.9 (S.E.) ng% in 15 females (p greater than 0.3).