Relationship of 19-nor-deoxycorticosterone to other mineralocorticoids in low-renin hypertension

A number of mineralocorticoids have been proposed as etiologic factors in low-renin hypertension. In this study, urinary free 19-nor-deoxycorticosterone (UF 19-nor-DOC) was compared to other mineralocorticoids--aldosterone, deoxycorticosterone (DOC), and 18-OH-DOC, in 11 low-renin hypertensive patients on a controlled diet in a metabolic unit. Results demonstrated that both UF 19-nor-DOC and tetrahydro-DOC (TH-DOC) excretion were elevated (2086 +/- 926, nl = 339-579 ng/day, and 18 +/- 7, nl = 5-15 mcg/day, respectively), and positively correlated (r = 0.95). Neither 18-OH-DOC nor aldosterone secretion rates were elevated, and neither of these hormones correlated with UF 19-nor-DOC, with exception of the supine plasma aldosterone (SPA) (r = 0.86). In conclusion, both UF 19-nor-DOC and TH-DOC were increased and positively correlated in the present series of hypertensives. This association is possibly indicative of a precursor-product relationship between DOC and 19-nor-DOC. 19-Nor-DOC, furthermore, correlated with supine plasma aldosterone (SPA), which could, in part, reflect their shared adrenocorticotropic hormone (ACTH) dependence.     

Sodium loading raises urinary cortisol in man

It has been suggested that cortisol secretion is modified by sodium intake. We therefore studied the pituitary-adrenal axis by measuring diurnal rhythms of ACTH and cortisol levels in serum of 10 normal control subjects after 4 days of low sodium diet (intake 40 mEq/day) and after 6 days of high sodium diet (intake 320 mEq/day). Urinary excretion of aldosterone-18-glucuronide and free cortisol were determined at the end of each diet. Urinary aldosterone excretion declined from 17.9 +/- 2.6 to 2.8 +/- 1.1 microgram/day and urinary cortisol increased from 26.2 +/- 6.2 to 36.8 +/- 13.8 micrograms/day during low and high sodium intake. In contrast, plasma ACTH and serum cortisol measured every two hours for a 24-h period were similar both during low and high sodium intake. The results suggest an altered handling of cortisol by the kidney during high salt intake.     

Urinary 18-hydroxycortisol and its relationship to the excretion of other adrenal steroids

The urinary excretion of 18-hydroxycortisol was recently reported to be increased in patients with primary aldosteronism who have an adrenal adenoma and in those with glucocorticoid-suppressible aldosteronism. A direct RIA for 18-hydroxycortisol in urine and plasma has been described, and we here report our experience using a similar direct RIA and a more elaborate RIA which includes a preliminary high pressure liquid chromatography (HPLC) purification step. The urinary excretion of 18-hydroxycortisol was compared with that of other adrencorticoids. The urinary excretion of 18-hydroxycortisol in 37 normal subjects using the direct RIA was 112 +/- 49 (+/- SD) microgram/24 h, and that with the HPLC-RIA method was 63 +/- 36 micrograms/24 h. The accuracy and specificity of the HPLC-RIA assay method were confirmed by measuring the steroid after the HPLC step as the glycolic acid ester derivative. The urinary excretion of 18-hydroxycortisol correlated with that of cortisol (r = 0.36; P less than 0.01), 18-oxocortisol (r = 0.42; P less than 0.01), and 19-nordeoxycortisosterone (r = 0.71; P less than 0.001), but did not correlate with the excretion of aldosterone 18-oxoglucuronide (r = 0.25; P = 0.15942). Dexamethasone administration to five normal subjects significantly decreased 18-hydroxycortisol excretion from 81 +/- 47 to 23 +/- 8 micrograms/24 h. ACTH infusion in these subjects receiving dexamethasone significantly raised 18-hydroxycortisol excretion to 147 +/- 37 micrograms/24 h. Five days of a sodium-restricted diet (10 mmoles/day) resulted in a significant (P less than 0.02) increase in 18-hydroxycortisol excretion, but two of eight subjects had decreased excretion, although urinary aldosterone excretion increased, as expected. These studies demonstrate that the direct RIA significantly overestimates urinary 18-hydroxycortisol excretion. These studies also demonstrate that the major factor resulting 18-hydroxycortisol excretion is ACTH. However, since 18-hydroxycortisol excretion may increase during sodium depletion, angiotensin or other factors may also regulate its secretion.     

Alterations in the hypothalamic-pituitary-ovarian and the hypothalamic-pituitary-adrenal axes in athletic women

The functional integrity of the hypothalamic-pituitary-ovarian and hypothalamic-pituitary-adrenal axes was assessed by determining pulsatile LH, ACTH, and cortisol secretion during the early follicular phase in athletic women with regular menstrual cycles (CA; n = 9), athletic women with amenorrhea (AA; n = 9), and regularly cyclic sedentary women (CS; n = 8). The CA and AA women were not significantly different in body composition, exercise training, psychometric tests, or dietary consumption. The CA women had shorter luteal phases (P less than 0.05) and lower urinary excretion of pregnanediol glucuronide than the CS women. In the AA women, urinary estrone glucuronide, pregnanediol glucuronide, and LH excretion were low throughout a 30-day period. The CA women had a 24-h pattern of pulsatile LH secretion characterized by reduced frequency (P less than 0.05) and increased amplitude (P less than 0.05), yielding an overall increased 24-h mean level (P less than 0.05), but interpulse intervals similar to those in the CS women. During sleep, LH pulse frequency slowed in the CS and CA women, while pulse amplitude increased and the mean serum LH level decreased in both groups. The AA women had even fewer pulses (P less than 0.05) of normal amplitude occurring at much more variable (P less than 0.01) interpulse intervals. Sleep-associated changes in LH pulsatility were absent. Responses to a 10-microgram bolus GnRH dose revealed blunted (P less than 0.05) FSH release in CA and augmented (P less than 0.05) LH release in AA women. The groups did not differ in any 24-h ACTH pulse pattern parameter or in cortisol pulse frequencies. Yet, early morning (0200-0800 h) serum cortisol levels were higher (P less than 0.05) in both groups of athletes, and this elevation was extended through the day (0800-2000 h; P less than 0.001) and evening (2000-0200 h; P less than 0.05) in the AA women. The plasma ACTH and serum cortisol responses to bolus human CRH administration were blunted in the CA and AA women [change from baseline (delta) in ACTH, P less than 0.05 and P less than 0.01; delta cortisol, P less than 0.01 and P less than 0.01, respectively], but adrenal sensitivity (delta cortisol/delta ACTH ratio) was increased (P less than 0.05). The plasma ACTH and serum cortisol responses to meals also were blunted in the athletic groups (P less than 0.05).(ABSTRACT TRUNCATED AT 400 WORDS)     

Evidence for impaired activation of the hypothalamic-pituitary-adrenal axis in patients with chronic fatigue syndrome.

Chronic fatigue syndrome is characterized by persistent or relapsing debilitating fatigue for at least 6 months in the absence of a medical diagnosis that would explain the clinical presentation. Because primary glucocorticoid deficiency states and affective disorders putatively associated with a deficiency of the arousal-producing neuropeptide CRH can be associated with similar symptoms, we report here a study of the functional integrity of the various components of the hypothalamic-pituitary-adrenal axis in patients meeting research case criteria for chronic fatigue syndrome. Thirty patients and 72 normal volunteers were studied. Basal activity of the hypothalamic-pituitary-adrenal axis was estimated by determinations of 24-h urinary free cortisol-excretion, evening basal plasma total and free cortisol concentrations, and the cortisol binding globulin-binding capacity. The adrenal cortex was evaluated indirectly by cortisol responses during ovine CRH (oCRH) stimulation testing and directly by cortisol responses to graded submaximal doses of ACTH. Plasma ACTH and cortisol responses to oCRH were employed as a direct measure of the functional integrity of the pituitary corticotroph cell. Central CRH secretion was assessed by measuring its level in cerebrospinal fluid. Compared to normal subjects, patients demonstrated significantly reduced basal evening glucocorticoid levels (89.0 +/- 8.7 vs. 148.4 +/- 20.3 nmol/L; P less than 0.01) and low 24-h urinary free cortisol excretion (122.7 +/- 8.9 vs. 203.1 +/- 10.7 nmol/24 h; P less than 0.0002), but elevated basal evening ACTH concentrations. There was increased adrenocortical sensitivity to ACTH, but a reduced maximal response [F(3.26, 65.16) = 5.50; P = 0.0015). Patients showed attenuated net integrated ACTH responses to oCRH (128.0 +/- 26.4 vs. 225.4 +/- 34.5 pmol/L.min, P less than 0.04). Cerebrospinal fluid CRH levels in patients were no different from control values (8.4 +/- 0.6 vs. 7.7 +/- 0.5 pmol/L; P = NS). Although we cannot definitively account for the etiology of the mild glucocorticoid deficiency seen in chronic fatigue syndrome patients, the enhanced adrenocortical sensitivity to exogenous ACTH and blunted ACTH responses to oCRH are incompatible with a primary adrenal insufficiency. A pituitary source is also unlikely, since basal evening plasma ACTH concentrations were elevated. Hence, the data are most compatible with a mild central adrenal insufficiency secondary to either a deficiency of CRH or some other central stimulus to the pituitary-adrenal axis. Whether a mild glucocorticoid deficiency or a putative deficiency of an arousal-producing neuropeptide such as CRH is related to the clinical symptomatology of the chronic fatigue syndrome remains to be determined.     

Malnutrition and deficiency of insulin secretion in alcoholic cirrhosis. Study by the assay of urinary C-peptide

In order to evaluate the relationship between nutritional status and insulin secretion in cirrhosis, the following parameters of caloric (tricipital skin fold, prealbumin) and proteic (arm muscle size, transferrin, 24 h-urinary creatinine excretion) nutritional status were compared in 20 alcoholic cirrhotics and 10 normal subjects. Insulin secretion was evaluated in both groups by insulin and C-peptide response to an intravenous glucose tolerance test and by 24 h urinary excretion of C-peptide. When compared to normals, cirrhotics have lower values for all nutritional status parameters and individually for at least three of those in 14 (70 p. 100) patients. In cirrhotics there is a significant decrease of the 4-min poststimulative response of insulin and C-peptide, contrasting with higher basal and late poststimulative values than in normals. This contrast could be explained by a reduced metabolic clearance rate of insulin (consistent with insulin resistance) and of C-peptide (the urinary clearance of which is 2.5 times lower in cirrhotics than in normals). The 24-h urinary excretion of C-peptide, probably weakly dependent of this reduced clearance, is 50 p. 100 lower in cirrhotics: 12.9 +/- 1.6 nM/24 h than in normals: 26.0 +/- 2.4 nM/24 h (p less than 0.001). In cirrhotics there is a significant linear correlation between 24 h urinary C-peptide excretion and all the nutritional status parameters but one (prealbumin). These results indicate that in cirrhosis: 1) urinary C-peptide excretion rate is a good index of insulin secretion; 2) urinary C-peptide indicates a marked deficit in insulin secretion.(ABSTRACT TRUNCATED AT 250 WORDS)     

Twelve-hour cycles of adrenocorticotropin and cortisol secretion in Cushing's disease

A 50-yr-old woman presented with a 7-yr history of Cushing's syndrome. She had high urinary free cortisol levels (711 micrograms/day) and a positive response to metyrapone and suppression with 8 mg dexamethasone, suggesting pituitary ACTH-dependent adrenocortical hyperfunction. Plasma cortisol and ACTH levels showed marked temporal variation. Samples obtained at 2-h intervals revealed that plasma ACTH and cortisol levels surged during periods lasting approximately 12 h and fell to levels below normal during the remainder of the 24-h cycle. When urinary free cortisol was measured in urines collected in 12-h aliquots, the corresponding surge in free cortisol excretion was also evident. These cycles were not affected by a 2.5-month course of cyproheptadine. Pituitary irradiation and mitotane therapy resulted in remission of Cushing's syndrome, with disappearance of the peaks of ACTH and cortisol secretion. This case represents an unusual example of the abnormal circadian rhythm of ACTH secretion on Cushing's disease.     

Plasma levels of atrial natriuretic factor in mild to moderate hypertensives without signs of left ventricular hypertrophy: correlation with the known duration of hypertension

The relationship between plasma atrial natriuretic factor (ANF), blood pressure (BP), age, plasma renin activity (PRA) and urinary sodium excretion was studied in 64 normal subjects (mean age 48.7 +/- 2.1 yrs; BP: 126.5 +/- 1.6/79.5 +/- 0.9 mmHg) and in 104 untreated uncomplicated essential hypertensives (50.8 +/- 1.1 yrs; BP: 164.7 +/- 1.6/105.2 +/- 0.6 mmHg). ANF was measured by radioimmunoassay after extraction on C18 columns. ANF was significantly higher in the hypertensives than in the normal subjects (37.1 +/- 1.2 vs 29.7 +/- 1.5 pg/ml, P less than 0.01). In normals plasma ANF was significantly correlated with age (r = 0.72, P less than 0.001), Na excretion (r = 0.42, P less than 0.001) and PRA (r = -0.71, P less than 0.001) whereas in the hypertensives ANF plasma levels correlated only with systolic (r = 0.46, P less than 0.001) and diastolic (r = 0.51, P less than 0.001) BP. In addition in hypertensive patients, by multivariate linear regression analysis, a significant correlation was found between age, known duration of hypertension and plasma ANF. The partial correlation coefficient between duration of hypertension and plasma ANF was highly significant (r = 0.80, P less than 0.001). These findings suggest that in essential hypertension the level of arterial BP is a main determinant of the ANF plasma values offsetting the ability of other physiological factors to regulate plasma ANF levels.     

Origin of aldosterone in trypsin-stimulated rat adrenal zona glomerulosa incubations.

The time-course for the in-vitro secretion of aldosterone and 18-hydroxycorticosterone (18-OH-B) by rat adrenal whole capsular tissue (largely zona glomerulosa) was studied under control and stimulated conditions. The stimulatory effect of trypsin was relatively delayed, and the steroids were significantly enhanced only after 1 h, in contrast to the actions of ACTH, which produced effects after 15 or 30 min. Tissue-sequestered 18-hydroxydeoxycorticosterone (t-18-OH-DOC), which is not affected by ACTH, was significantly depleted by trypsin, but secreted 18-OH-DOC was not consistently affected by either stimulant. In contrast to the apparent mobilization of t-18-OH-DOC, the conversion of exogenously added [3H]18-OH-DOC to [3H]18-OH-B was inhibited by trypsin, and aldosterone was unaffected. When trilostane was added to inhibit de-novo steroidogenesis, under conditions in which the steroid secretory response to ACTH is completely inhibited, aldosterone and 18-OH-B secretion was still stimulated by trypsin although yields were lower. Compared with controls, trilostane reduced t-18-OH-DOC concentrations, and trypsin caused a further depletion. In other studies, glomerulosa plasma membrane enriched preparations were homogenized and centrifuged, and the supernatants were dialysed and added to incubations of dispersed zona glomerulosa cells in the presence or absence of stimulators of aldosterone secretion.(ABSTRACT TRUNCATED AT 250 WORDS)     

Vasopressin secretion in normotensive black and white men and women on normal and low sodium diets

The plasma concentration and the 24-h urinary excretion of vasopressin were studied in normal black and white men and women on a normal sodium (150 mmol/day) diet for 3 days and a low sodium (9 mmol/day; furosemide, 1 mg/kg on first day) diet for 4 days. During the normal sodium diet, the 24-h urinary excretion of vasopressin was significantly (P less than 0.05) higher in men than in women and higher (P less than 0.05) in black than in white subjects. Corresponding differences in plasma vasopressin concentrations (P less than 0.05 to 0.01) were observed, with the exception that the difference between white men and women was not statistically significant. These data suggest that under basal conditions the secretion of vasopressin is higher in men and black subjects than in women and white subjects, although differences in the metabolic clearance of vasopressin cannot be ruled out. Reduction in sodium intake resulted in a significantly (P less than 0.01) decreased excretion of vasopressin in all groups except black women, but had no effect on plasma vasopressin concentrations. Significant (P less than 0.01) differences with respect to sex and race persisted for vasopressin excretion, but not for plasma vasopressin concentrations. Sex- and race-related differences in vasopressin could not be attributed to differences in blood pressure, plasma volume or plasma sodium concentration. The physiological consequences of these differences in vasopressin remain to be determined.     

Alterations in aldosterone secretion and metabolism in low renin hypertension

Low renin essential hypertensives (LRH) have normal plasma aldosterone levels which are inappropriately high in relation to their PRA. Posture is the major determinant for plasma aldosterone and PRA levels, but it is not known whether postural increments (delta) of plasma aldosterone and (delta) PRA are also abnormal in LRH. To evaluate this, LRH (n = 8), normal renin hypertensives (NRH; n = 9), normotensive controls (n = 18), and subjects with idiopathic hyperaldosteronism (IHA; n = 5) were studied in a metabolic unit on a controlled diet over 7 days. Overnight supine and 4-h upright PRA, plasma aldosterone, and 24-h urinary tetrahydroaldosterone (THA) and aldosterone secretion rates (ASR) were measured. The delta in plasma aldosterone after 4 h of upright posture was not different in the four groups. The ratio of delta plasma aldosterone/delta PRA, however, was elevated in both IHA and LRH compared to that in NRH and normals. THA excretion was also elevated in IHA and LRH, but LRH had a normal ASR. This resulted in a higher fractional THA excretion (THA/ASR) in LRH compared to the other three groups. These data further support enhanced adrenal angiotensin-II sensitivity in LRH. Aldosterone was preferentially metabolized to THA in LRH. Since THA has reduced biological activity, this may be a compensatory mechanism to reduce mineralocorticoid activity in LRH.     

Endocrinologic and psychologic evaluation of 21-hydroxylase deficiency carriers and matched normal subjects: evidence for physical and/or psychologic vulnerability to stress

Carriers of congenital adrenal hyperplasia due to 21-hydroxylase (21-OH) deficiency demonstrate increased secretion of cortisol precursors after ACTH stimulation, suggestive of impaired cortisol production and compensatory increases in hypothalamic CRH secretion. Because both cortisol and CRH have behavioral effects, and hypothalamic CRH hypersecretion has been associated with chronic states of anxiety and depression, we performed endocrine and psychologic studies in consecutively admitted parents of patients with classic congenital adrenal hyperplasia due to 21-OH deficiency and parents of children with other chronic endocrine disorders. The number of excluded carriers because of pathologic reasons was higher than that of controls (P = 0.05). Carriers of 21-OH deficiency had a lower mean 24-h urinary free cortisol excretion (26.4 +/- 3.4 vs. 42.7 +/- 6.4 microg/d, P = 0.03) and higher peak ACTH (75.7 +/- 8.1 vs. 54.2 +/- 5.9 pg/ml, P = 0.04) and 17-hydroxyprogesterone (224.2 +/- 28.1 vs. 107.1 +/- 12.5 ng/dl, P < 0.001) concentrations post CRH stimulation than control subjects. Cortisol and androstenedione responses were similar in the two groups. Psychometric assessment performed by administering the State-Anxiety Inventory, Beck Depression Inventory, Profile of Mood States, Symptom Checklist-90R, and Temperament and Character Inventory revealed no differences between the two subject groups. Interestingly, a stepwise multiple linear regression model analysis in each population sample revealed that in carriers of 21-OH deficiency but not in the control subjects, a lower mean 24-h urinary free cortisol excretion and a higher ACTH response to ovine CRH stimulation predicted predisposition to obsessive-compulsive behavior, novelty seeking, reward dependence, and harm avoidance. We conclude that carriers of 21-OH deficiency appear to have mild hypocortisolism and compensatory changes of CRH secretion secondary to lower cortisol concentrations. These changes might predict mild predisposition of these subjects to physical and psychologic pathology, suggesting that larger studies are necessary.     

Effect of adrenal suppression with dexamethasone in essential hypertension.

The 24-h integrated plasma concentration of aldosterone (IC-ALDO), PRA (IC-PRA), and cortisol (IC-F) were measured in 34 male patients with uncomplicated mild essential hypertension and 15 matched normal controls using a portable 24-h continuous nonthrombogenic blood withdrawal system. The hypertensive were subsequently given 0.5 mg dexamethasone three times per day, resulting in suppression of their urinary excretion of 17-hydroxycorticosteroids and free cortisol. The diastolic blood pressure of the hypertensives fell during adrenal suppression from 104 +/- 5 to 96 +/- 8 mm Hg (mean +/- 1 SD; P less than 0.0001). The systolic pressure fell from 150 +/- 16 to 148 +/- 17 (P greater than 0.01). Baseline values for IC-F, IC-ALDO, and IC-PRA were similar in hypertensive subjects and normal controls. After treatment with dexamethasone for 8 weeks, IC-F in the hypertensives decreased from 7.8 +/- 2.1 to 0.7 +/- 0.6 microgram/dl (P less than 0.0001). There was no associated change in IC-ALDO or IC-PRA. Thus, the fall in diastolic blood pressure in response to dexamethasone was associated with suppression of IC-F, without demonstrable changes in other endocrine or biochemical factors measured.     

EFFECTS OF INHIBITION OF CHOLESTEROL SYNTHESIS BY SIMVASTATIN ON THE PRODUCTION OF ADRENOCORTICAL STEROID HORMONES AND ACTH

Simvastatin, a derivative of lovastatin, is a potent inhibitor of cholesterol biosynthesis and may interfere with steroid hormone production, for which cholesterol is required. In a single-blind, placebo-controlled study, 24 patients with severe primary hypercholesterolaemia (mean serum cholesterol +/- SD = 10.74 +/- 1.59 mmol/l) were treated with simvastatin 40 mg per day for 8 weeks. Before and after treatment, the following parameters were evaluated: basal levels of ACTH, cortisol, androstenedione, dehydroepiandrosterone and 17-hydroxyprogesterone; urinary excretion of free cortisol; the cortisol response after short-term infusion of ACTH; the ACTH and cortisol response during insulin-induced hypoglycaemia. Total serum cholesterol decreased by 35.0 +/- 8.1% (P less than 0.001) and low-density lipoprotein (LDL) cholesterol by 39.8 +/- 9.8% (P less than 0.001); high-density lipoprotein (HDL) increased by 9.2 +/- 11.1% (P less than 0.001). Basal levels of ACTH were higher after simvastatin (2.9 +/- 1.9 pmol/l vs 4.1 +/- 2.9 pmol/l; P less than 0.05) whereas basal levels of steroid hormones were not significantly changed. The excretion of free cortisol was unaltered. The peak cortisol after ACTH infusion was lower after treatment (0.87 +/- 0.23 mumol/l vs 0.78 +/- 0.10 mumol/l; P less than 0.05), but was unaltered during insulin-induced hypoglycaemia. We conclude that simvastatin lowers serum cholesterol without clinically relevant effects on the adrenocortical steroid hormone secretion and the hypothalamic-pituitary-adrenal axis.     

The relationship of adrenal iodomethylnorcholesterol uptake to indices of adrenal cortical function in Cushing's syndrome

The adrenal gland uptake of 131I-6-beta-iodomethyl-19-norcholesterol (NP-59) was calculated using a semioperator-independent computer algorithm in 17 patients with Cushing's syndrome (CS). Twelve had ACTH-dependent and 5 had ACTH-independent CS. The mean adrenal gland uptake (percentage of administered dose) of NP-59 was 0.74 +/- 0.18% (range, 0.21-2.02%) in CS and was significantly higher than that of normal subjects (0.33 +/- 0.02%). Patients with the ectopic ACTH syndrome and ACTH-independent CS manifested the highest uptakes (mean, 1.18 +/- 0.08%; range, 0.74-2.02%). In the patients with ACTH-dependent CS, a significant correlation was observed between 24-h urinary free cortisol excretion and NP-59 adrenal gland uptake (r = 0.97, P less than 0.001). No relationship was seen between NP-59 uptake and urinary free cortisol in ACTH-independent CS or between NP-59 uptake and urinary 17-hydroxycorticosteroids, 17-ketosteroids, cortisol secretion rate, plasma cortisol, or ACTH levels in either ACTH-dependent or ACTH-independent CS. We conclude that in addition to localizing the sites(s) of adrenocortical hypersecretion in CS, the level of NP-59 adrenal uptake is a reflection of cortisol excretion in ACTH-dependent disease and may be utilized as another parameter to quantitate adrenal disease activity in CS.     

Urinary growth hormone (GH) measurements are useful for evaluating endogenous GH secretion

Daily (24-h) urinary GH excretion was measured using a highly sensitive sandwich enzyme immunoassay in 10 normal adults, 6 patients with hypopituitarism, 25 normal but short children who had normal plasma GH responses (peak plasma GH level, greater than 10 micrograms/L) to provocative tests, and 8 patients with acromegaly. The mean urinary GH values in the normal adults, patients with acromegaly, and patients with hypopituitarism were 13.8 +/- 4.0 (+/- SE) and 431.1 +/- 149.1 ng/g creatinine (Cr) (1.56 +/- 0.45 and 48.77 +/- 16.87 ng/mmol Cr) and undetectable, respectively; these mean values were significantly different from each other. In the normal but short children the urinary values ranged from undetectable to 55.8 ng/g Cr (6.31 ng/mmol Cr). All of the normal but short children and 4 patients with hypopituitarism participated in a 24-h endogenous GH secretion study. The urinary GH values correlated significantly with the mean 24-h plasma GH concentrations as an index of endogenous GH secretion (r = 0.81; P less than 0.001) and plasma somatomedin-C levels (r = 0.67; P less than 0.001), respectively. In 6 patients with acromegaly whose plasma GH levels were constant throughout a 4-h period, the urinary GH values also significantly correlated with the mean plasma GH levels (r = 0.95; P less than 0.01). These data indicate that urinary GH measurements reflect endogenous GH secretion and that measurement of urinary GH excretion is a useful, simple, and practical method for evaluating endogenous GH secretion.     

Effects of carbamazepine on pituitary-adrenal function in healthy volunteers.

Carbamazepine (CBZ) is a widely used therapeutic agent in seizure, pain, and mood disorders. Although CBZ has been shown to inhibit hypothalamic CRH secretion in vitro, limited data suggest that systemic CBZ induces pituitary-adrenal activation. Few data are available to reconcile these effects or clarify their mechanism(s), particularly in healthy human subjects. We report here a study of basal ACTH and cortisol secretion and their responses to ovine CRH administration in nine healthy volunteers, studied both during repeated (2-3 weeks) administration of CBZ and while medication free. CBZ significantly increased mean 24-h urinary free cortisol (mean +/- SE, 197 +/- 17 vs. 137 +/- 24 nmol/day; P less than 0.02) and evening basal total plasma cortisol (113 +/- 17 vs. 83 +/- 14 nmol/L; P less than 0.05) as well as cortisol-binding globulin-binding capacity (497 +/- 36 vs. 433 +/- 28 nmol/L; P less than 0.01). Despite the CBZ-induced hypercortisolism, plasma ACTH responses to CRH during CBZ treatment remained robust, rather than being suppressed by basal hypercortisolism. In fact, during CBZ treatment, we noted a positive correlation between the increase in basal plasma cortisol and the increase in the plasma ACTH response to CRH (r = 0.65; P less than 0.05). We also observed a reduction in cortisol-binding globulin-binding capacity after CRH administration (315 +/- 25 vs. 433 +/- 28 nmol/L; P less than 0.001), which was accentuated by CBZ treatment (342 +/- 19 vs. 497 +/- 36 nmol/L; P less than 0.001; magnitude of fall, -155 +/- 22 nmol/L on CBZ vs. -118 +/- 11 nmol/L off CBZ; P less than 0.05). We conclude that CBZ increases plasma cortisol secretion in healthy volunteers independent of its effect on plasma cortisol-binding capacity. This pituitary-adrenal activation seems to reflect a pituitary, rather than a hypothalamic, effect of CBZ. Hence, despite CBZ-induced hypercortisolism, the ACTH response to CRH remained robust in direct proportion to the CBZ-induced rise in basal plasma cortisol. Thus, we propose that the increased cortisol secretion observed during CBZ treatment reflects a relative inefficacy of glucocorticoid negative feedback at the pituitary. This pituitary-driven increase in cortisol secretion combined with the expected reduction in centrally directed CRH secretion could contribute to the anticonvulsant properties of CBZ.     

ADRENOCORTICOTROPHIN (ACTH) DEFICIENCY UNDETECTED BY STANDARD DYNAMIC TESTS OF THE HYPOTHALAMIC-PITUITARY-ADRENAL AXIS

Six patients (four females, two males; aged 18-65 years), previously treated by external pituitary irradiation (2000-4000 cGY in 8-15 fractions over 10-20 days) for pituitary tumours, presented with the symptoms of excessive and inappropriate tiredness suggestive of ACTH deficiency, despite a normal peak cortisol response to an insulin tolerance test (four cases) or to a glucagon stimulation test (two cases). These six patients were found to have significantly lower mean 24 h urinary free cortisol levels (100 +/- 40 nmol; mean +/- SD) compared with the mean value of 31 normal controls (210 +/- 70.8 nmol; P less than 0.01). In addition serum cortisol profiles based on a series of four timed samples between 0900-2300 h were subnormal (mean 130 nmol/l) in comparison with profiles obtained from 12 normal controls (mean 270 nmol/l) (P less than 0.001). Glucocorticoid replacement therapy promptly abolished their symptoms. These results suggest that a discordance between ACTH secretion under basal circumstances and ACTH response to pharmacological tests may exist in patients with ACTH deficiency. We speculate that defective endogenous corticotrophin-releasing hormone (CRF) secretion, due to radiation-induced damage at hypothalamic level, is one cause of this phenomenon.     

Increased Urinary C-Peptide and Albumin Excretion in Juvenile Borderline Hypertensives

The study was designed to evaluate the urinary excretion of C-peptide and albumin, and urinary N-acetyl-beta-D-glucosaminidase (NAG) activity in juvenile borderline hypertensives. The second aim was to examine the relationship between these variables and ambulatory blood pressure level and variability. The study group consisted of 21 non-obese males consecutively chosen from patients with borderline hypertension, defined by sphygmanometer readings, examined in our outpatient clinic. All subjects collected separately their day-time and night-time urines during the period of ambulatory blood pressure monitoring. In 16 patients, who were considered to have “sustained” borderline hypertension, both 24-h urinary C-peptide excretion and 24-h UAE were significantly increased in comparison to those of the controls, while NAG activity did not differ significantly between the two groups, UAE was significantly lower at night than during the day in both borderline hypertensives and controls. Twenty-four-hour UAE in borderline hypertensives correlated significantly with the ambulatory blood pressure variability, but not with the average blood pressure level. These results suggest that the 24-h insulin secretion rate estimated by means of urinary C-peptide excretion is significantly increased in “sustained” borderline hypertensives. Elevated UAE in juvenile borderline hypertensives can be explained by a possible direct effect of systemic blood pressure variability on albuminuria.     

The regulation of urinary free 19-nor-deoxycorticosterone and its relation to systemic arterial blood pressure in normotensive and hypertensive subjects

19-Nor-deoxycorticosterone (19-nor-DOC) is a naturally occurring, potent mineralocorticoid present in hypertensive animal models as well as man. To investigate 19-nor-DOC's regulation and possible pathogenesis in hypertension, urinary free (UF) 19-nor-DOC was measured in 14 hypertensives, correlated with other corticosteroids and systemic arterial blood pressure (BP), and compared to basal and ACTH-stimulated values in 8 normotensive subjects. Seven of the 14 hypertensives had low-renin hypertension, 2 had primary aldosteronism, 1 had an adrenal carcinoma, and another had acromegaly. These studies determined that: 1) although the mean UF 19-nor-DOC was not increased in hypertensives (588 +/- 180 vs. 428 +/- 122 ng/day), 2 low-renin hypertensives had quite elevated levels (2186 and 2018); 2) the UF 19-nor-DOC in hypertensives was correlated with BP but not with PRA, aldosterone secretion, plasma potassium, basal plasma cortisol, or 17-hydroxycorticosteroids; 3) likewise, in normotensives, UF 19-nor-DOC did not correlate with basal plasma cortisol, cortisol secretion, or 17-hydroxycorticosteroids excretion but did correlate after ACTH stimulation. Therefore, although 19-nor-DOC is activated by ACTH administration, it is not correlated with basal parameters of cortisol production, suggesting that factors other than ACTH regulate basal 19-nor-DOC secretion. Furthermore 19-nor-DOC is elevated in some hypertensive patients, and it is directly related to the elevation of mean systemic BP. This suggests that, although 19-nor-DOC could contribute to hypertensive disease in some individuals, it does not appear to be due to excess ACTH.