Adrenal function in normal infants and in marasmus and kwashiorkor: plasma aldosterone concentration and aldosterone secretion rate

Fetal endocrinology

Successful outcome of pregnancy depends upon genetic, cellular, and hormonal interactions, which lead to implantation, placentation, embryonic, and fetal development, parturition and fetal adaptation to extrauterine life. The fetal endocrine system commences development early in gestation and plays a modulating role on the various physiological organ systems and prepares the fetus for life after birth. Our current article provides an overview of the current knowledge of several aspects of this vast field of fetal endocrinology and the role of endocrine system on transition to extrauterine life. We also provide an insight into fetal endocrine adaptations pertinent to various clinically important situations like placental insufficiency and maternal malnutrition.

Neonatal undernutrition and short term administration of hydrocortisone and thyroxine: effects on rat brain hydrolases

Brain enzymes activities that are likely to be involved in the catabolism of gangliosides were determined in controls (20% casein diet), postnatally undernourished (6.5% casein diet) and undernourished rats treated with either thyroxine or hydrocortisone, at 21 days of age. Postnatal undernutrition imposed by maternal protein deficiency during lactation resulted in a decrease in body weight and brain wet weight of the pups at 21 days of age. Administration of thyroxine or hydrocortisone to the undernourished pups every day between 16 and 21 days caused a further decrease in the body weight of the pups. On the other hand, the wet weight of brain showed a slight gain following hydrocortisone treatment. Postnatal undernutrition during lactation elevated the activities of beta-glucosidase, beta-galactosidase, beta-hexosaminidase and sialidase in rat brain. Short-term administration of thyroxine or hydrocortisone to the undernourished pups, every day between 16 and 21 days postnatal age decreased the enzyme activities. However, reversal of the increased enzyme activities to the normal lower level was completed only in the case of undernourished pups treated with hydrocortisone.

Circulating gonadotropin profile in severe cases of protein calorie malnutrition

The circulating levels of luteinizing hormone (LH), follicle-stimulating hormone (FSH), and prolactin (PRL) were studied in children of both sexes between 2 and 14 years of age who were suffering from severe protein calorie malnutrition (PCM), namely, kwashiorkor, marasmic kwashiorkor, and marasmus. LH and FSH levels in all the age groups and in all forms of PCM were found to be significantly lowered, thereby explaining the possible delay in the onset of puberty in these children. Circulating PRL levels, on the other hand, were significantly raised in all patients with PCM studied, with values in children with kwashiorkor and marasmic kwashiorkor higher than in children with marasmus, possibly accounting for the presence of edema in the former cases. The present work, therefore, proposes a possible correlation between gonadotropin levels and PCM in children.

Regulation of aldosterone secretion in dehydrated babies

The factors controlling aldosterone secretion were measured in 12 patients with moderate to severe dehydration during the first year of life. Secondary hyperaldosteronism was present in all cases (mean plasma aldosterone concentration 414.6 ng/dl), as well as increased plasma cortisol levels (mean 49.7 microgram/dl). Plasma cortisol, an indirect parameter of stimulation of the adrenal cortex by ACTH, showed the highest correlation with plasma aldosterone (r = 0.82). Despite a mean elevation of 168 ng AT/ml/h the plasma renin concentration did not seem to play the dominant role in the regulation of aldosterone secretion in these infants. High serum sodium concentrations have a clearly inhibiting effect on aldosterone secretion as shown by the negative correlation coefficient of r = 0.80.

Behaviour of plasma renin activity and aldosterone during the first 72 h of life

Plasma renin activity (PRA) and plasma aldosterone concentrations (PAC) were determined in fifty normal newborns during the first 72 h of life. PRA was elevated in all cases and tends to increase from the first (6.79 +/- 0.69SE ng/ml/h) to the third day of life (8.24 +/- 0.96SE ng/ml/h). PAC was also elevated and rose from 24.06 +/- 3.23SE ng/dl on the first day to 39.20 +/- 4.25SE ng/dl on the third day. No significant correlation was observed between PRA and PAC. Serum sodium was within the normal range, whereas serum potassium was slightly elevated during the first 48 h of life. The physiological significance of the high levels of PRA and PAC in newborns is not clear at present. Many factors may be involved in the increased activation of the renin-angiotensin-aldosterone system: low blood pressure, hypersensitivity of the macula densa to catecholamines, relative insensitivity of the immature kidney to aldosterone, hyperkalaemia and other control mechanisms for aldosterone secretion all of which probably operate simultaneously during the first days of life.

Potassium-renin-aldosterone relationships during the first year of life

In order to gain insight into factors controlling aldosterone secretion during the first year of life, we studied the relationships between PRA, serum potassium, sodium, and serum aldosterone levels. While we found a dissociation during the early neonatal period, there was a high degree of correlation between serum aldosteron, PRA, and serum potassium by 3 to 12 months of age. This suggests that aldosterone secretion in the 3- to 12-month-old child, as in adults, is regulated by the circulating levels of potassium and angiotensin II.

Adrenal function in normal infants and in marasmus and kwashiorkor. Cortisol secretion, diurnal variation of plasma cortisol, and urinary excretion of 17-hydroxycorticoids, free corticoids, and cortisol

Normal infants exhibited circadian rhythmicity of plasma F concentration. Infants from 2.1 to 3.2 months of age had CSR significantly higher than those of older infants. THF/THE urinary excretion ratios increased with age. The 17OHCS excretion was higher in the younger infants. Urinary excretions of free corticoids and cortisol were similar in all age groups. In marasmus, plasma F concentrations in the morning and evening were significantly elevated. Normal diurnal variation returned following therapy. CSR and 17OHCS excretions were not different from age controls, but were significantly lower than size controls, THF/THE ratios, urinary excretion of free corticoids and cortisol were normal. In marasmic kwashiorkor, plasma F concentrations were significantly elevated in the morning and evening. There was a suggestive decrease with therapy. CSR was low before and after treatment. THF/THE ratios, urinary 17OHCS excretion, and urinary free corticoids and cortisol were not significantly different from infants matched for size or patients with marasmus.