We compared the reproducibility and repeatability of the acute adrenal response to low doses (90 and 500 ng/1.73 m2) of Synacthen (ACTH(1-24)) with that of the standard dose (250 micrograms/1.73 m2). We also examined the effect of basal cortisol levels on peak values achieved after stimulation with a low dose. ACTH(1-24) was given to six male volunteers: 90 ng/1.73 m2 twice at 90-min intervals on day 1, and 90 and 500 ng/1.73 m2 once on day 2 and 250 micrograms/1.73 m2 once on day 3. The rise in serum cortisol concentration with repeated low doses of ACTH was not attenuated (161 +/- 49 (S.D.) nmol/l on initial vs 150 +/- 41 nmol/l on repeat stimulation; P = 0.5) and this was reproducible (161 +/- 49 nmol/l on day 1 vs 148 +/- 15 nmol/l on day 2; P = 0.6). A dose of 500 ng ACTH(1-24)/1.73 m2 produced a maximal adrenal response in that the rise in serum cortisol concentration at 20 min was identical with that produced at the same time by the standard dose of 250 micrograms/1.73 m2. There was a strong positive correlation between the basal cortisol level and peak cortisol concentration after low-dose ACTH stimulation (r = 0.93, P < 0.001) but not between the basal cortisol level and the incremental rise (r = -0.1, P = 0.69). These results suggest that the cortisol response to low-dose ACTH stimulation is reproducible and not attenuated by repeat stimulation at 90-min intervals.(ABSTRACT TRUNCATED AT 250 WORDS)

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SUMMARY 10 infants are described with pseudohypoaldosteronism, 5 in detail and a further 5 briefly. They all presented with hyperkalaemia, urinary salt-wasting disease, and ostensibly normal renal and adrenocortical function. Diagnosis was established by demonstrating the greatly increased values of plasma renin activity and plasma aldosterone concentration, plus the increased excretion of aldosterone and its metabolites on gas chromatographic and mass spectrometric analyses of urine. The children were treated with sodium chloride supplements, up to 60 mmol/day, but by the time most of the infants were about a year old these could be stopped. Exogenous mineralocorticoids were without effect in those to whom they were administered. The precise aetiology of the condition remains conjectural; lack of renal tubular response to aldosterone seems probable. Pseudohypoaldosteronism may be more common than has been thought and new techniques for investigating salt-wasting disorders may show its true incidence.

Background The outcome of parathyroid surgery is often not clear for at least 24 h after the operation. A frozen section does not always distinguish between an adenoma and hyperplasia. Minimally invasive surgical techniques are being refined, so the need for perioperative assurance about the completeness of surgery has increased. The value of intraoperative parathyroid hormone (PTH) measurements in 26 surgical cases undergoing parathyroidectomy has been evaluated.

Hypertension was produced in Sprague-Dawley rats by intramuscular injections of either corticosterone or ACTH. Lower increases in blood pressure to these challenges were observed in Sprague-Dawley rats pretreated with neomycin or vancomycin which alone had no effect on blood pressure or growth. The development of high blood pressure in spontaneously hypertensive rats of a stroke-prone substrain was also attenuated by oral administration of neomycin. These results suggest that experimental hypertension can be modulated by the administration of antibiotics.