Diurnal patterns of secretion of cortisol and growth hormone in normal adolescents, in patients with exogenous and endogenous Cushing's syndrome, in patients with diabetes mellitus, and in a fasting subject

The role of respiratory infections in airway hyperresponsiveness and asthma

Viruses provoke symptoms of wheezing in many patients with asthma. Furthermore, there is evidence that viruses increase airway responsiveness in non-asthma patients. The mechanisms involved in these reactions are not clearly established, but evidence suggests that the ability of viruses to promote this bronchial responsiveness may be related to an upregulation of the allergic inflammatory reaction. This would explain why patients may be more prone to have a late asthmatic reaction.

Evidence for two subtypes of Cushing's disease based on the analysis of episodic cortisol secretion

To investigate the pathogenetic mechanisms of Cushing's syndrome, we studied variations in plasma cortisol levels (episodic variations, or pulses) over 24 hours in 51 normal subjects, 14 patients with adrenal adenoma, and 46 patients with Cushing's disease. Data were obtained both from our patients and from the literature. As compared with normal subjects, patients with adrenal adenoma had fewer spikes in cortisol levels (defined as an elevation of at least 10 per cent and no less than 1 microgram per deciliter), and the spikes were lower both in absolute terms (4.0 +/- 1.8 vs. 5.1 +/- 2.2 micrograms per deciliter, P less than 0.05) and in terms of the percentage of the preceding trough concentration (23 +/- 7 vs. 123 +/- 74 per cent, P less than 0.001). Patients with Cushing's disease seemed to fall into two groups: those with hypopulsatile and those with hyperpulsatile secretion. The hypopulsatile group had a normal number and absolute height of spikes, but their height relative to the preceding trough concentration was lower than in controls (42 +/- 16 vs. 123 +/- 74 per cent, P less than 0.005). In contrast, the hyperpulsatile group had a similar number of spikes as the hypopulsatile group, but their absolute and relative heights were twice as great (12.7 +/- 2.3 vs. 6.0 +/- 1.6 micrograms per deciliter and 84 +/- 40 vs. 42 +/- 16 per cent, respectively; P less than 0.001 for both). We hypothesize that the Cushing's disease in the second group of patients may have been caused by increased hypothalamic release of, or pituitary responsiveness to, corticotropin-releasing factor, whereas that in the first group may represent pituitary oversecretion of corticotropin that is relatively independent of corticotropin-releasing factor.

Hypothalamic control of GH secretion: pathophysiology and clinical implications

GH is secreted episodically. Its pattern is regulated by the interplay of a releasing and a release-inhibiting hormone of hypothalamic origin. Modulation occurs by metabolic factors (glucose, free fatty acids, ketone bodies, amino acids). Altered GH secretion has been observed in states of metabolic derangement such as diabetes mellitus, malnutrition and obesity. Further modulation occurs by extrahypothalamic CNS structures. In man--but not in animals, including subhuman primates--sleep has an important effect on GH secretion. A defective GH secretory pattern has been found to occur in several states of sleep disturbance, such as sleep deprivation, narcolepsy, severe psychosocial derangement, the apallic syndrome. Other CNS influences on GH secretion are related to stress, emotional changes and psychiatric disturbances. The exact mechanisms by which most of these influences are relayed to the GH secretory apparatus of the hypothalamus remain yet to be investigated.

Glucocorticosteroids and growth hormone secretion under physiological conditions and in states of steroid excess

Cortisol and growth hormone (GH) secretion (spontaneous variations at night and the release induced by insulin hypoglycaemia) were investigated in 69 children and adolescents. Statistical analysis of approximately 600 pairs of cortisol and GH values in this study demonstrated that physiological fluctuations of cortisol do not alter GH secretion. A review of the literature shows that GH secretion is consistently depressed in Cushing's disease of central origin and in Cushing's syndrome due to adrenal carcinoma. When acutely administered, doses higher than 100 mg of cortisol (or equivalent amounts of other steroids) per adult are necessary to block GH secretion and the hormones have to be given several hours previously. In long-term steroid treatment, suppression of GH is observed in only 1 out of 3 patients. The effect apparently does not persist beyond elimination of the last dose, i.e. generally not longer than 12 to 24 h. These data can be taken as a rationale for intermittent or alternating dosage schedules, and for the use of short acting derivatives if long-term, high-dose steroid treatment is necessary in children. It remains to be established whether growth deficiency in exogenous hypercortisolism is due to suppression of GH secretion, decreased production of somatomedins, direct antagonism of the action of somatomedins on growing cartilage, or a combination of these mechanisms.

Repeated circadian growth hormone, luteinizing hormone, and follicle-stimulating hormone in children: influence of 9-alpha-fluorohydrocortisone

Growth hormone (GH), luteinizing hormone (LH), and follicle-stimulating hormone (FSH) in plasma of 5 children at different pubertal stages and suffering from moderate orthostatic complaints, were measured by radioimmunoassay (RIA). Parameters for secretory capacity were arginine loading and circadian hormonal patterns in hourly intervals from 8 a.m. to 8 p.m. and in half-hourly intervals from 8 p.m. to 8 a.m. before and after 6 weeks treatment with 9-alpha-fluorohydrocortisone (9-alpha-F, Astonin-H, Fa. Merck, Darmstadt, 0.1--0.2 mg/day. Plasma GH during arginine tests and in circadian levels remained unchanged, but circadian LH showed a consistent slight rise in all children. With pubertal development, magnitude and timing of GH peaks increased in boys, and rather decreased in the two girls toward late puberty. Episodic fluctuation of LH and FSH were more marked during sleep, and increased in the three bosy as puberty advanced. Similar intraindividual patterns for GH and LH, but not for FSH were noted in 4 children. Timing of GH and LH peaks appeared to be correlated. An intrinsic hereditary long-term regulatory principle is discussed.