Proceedings: Plasma renin activity and aldosterone concentration in children

Concentrations of circulating steroids in normal prepubertal and adult male and female humans, chimpanzees, rhesus monkeys, rats, mice, and hamsters: a literature survey

Radioimmunoassay (RIA) data on concentrations of circulating steroids in normal prepubertal and adult male and female humans, chimpanzees, rhesus monkeys, rats, mice, and hamsters have been collated from the literature. Few reports include data for both sexes, for age groups, or for more than one species. In selecting references for inclusion in the tables, efforts were made to choose data only from RIA procedures that were adequately validated. A number of similarities can be found by reviewing the tables. Levels of estradiol appear somewhat similar for humans, chimpanzees, and rhesus monkeys of both sexes. Among the notable differences are the levels of estradiol and progesterone in primates and rodents, the apparently high level of aldosterone in mice, and the patterns of progesterone secretion in mice and rats. All values in the tables have been converted to picograms for easy comparison between steroids and species. Data for humans are fairly complete, but there is a significant lack of information for several other species.

High blood pressure in children: problems and guidelines for evaluation and treatment

Evidence is presented from studies of the authors and of other investigators that primary hypertension is more common in children than was previously thought. Ninety-five percent of 131 asymptomatic children with incidental hypertension were considered to have primary hypertension after investigation for possible causes. The definition of hypertension was based on normal ranges of blood pressure for each age and sex. However, the definition of juvenile hypertension is still unsettled as is the question of treatment. Investigation of the effect of prolonged antihypertensive therapy on growth and development is needed. Primary hypertension in the young makes possible the study of the disease at its inception.

Fluid and electrolyte metabolism in the newborn infant

This chapter has sought to gather together the background information on systems controlling homoeostasis of salt and water and their clinical derangement. The temptation to adopt an all-embracing approach to the management of these problems is strong but such an approach is difficult to achieve and indeed dangerous. The circumstances of each sick infant are unique and plans for treatment must be individually tailored and flexible, dependent upon clinical and biochemical progress. Future developments in this field are likely to involve further understanding of renal and hormonal control of fluid and electrolyte and it might be expected that as new methods of management emerge they will be accompanied by their own peculiar risks of inducing secondary homoeostatic disturbances. With regard to infant feeding each advance appears to underline the desirability of breast feeding and support current moves toward provision of low solute feeds for those who are artificially fed. Paediatricians should be vocal in their advocation of breast feeding and ensure that the major principles of salt and water handling are understood by all who work with small infants. An extra scoop of powdered milk can be more of a poison than a food.

Severe hypertension of renal ischaemic origin

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Measurement of plasma renin activity by semi-micro radioimmunoassay of generated angiotensin I

A semi-micro method for determination of plasma renin activity (PRA) by radioimmunoassay of generated angiotensin I (AI) is described. The method permits measurement of PRA on 250 mul of plasma without loss of specificity, sensitivity, accuracy or preision. The small sample size has considerable application in terms of investigation of infants and young children. A reference range was established for healthy children on free diets. There was a 15-fold decline in PRA with age from a mean value of 1404pgAI/ml h-1 (ngAI/1. h-1) in infancy to a mean of 85 pgAI/ml h-1 (ngAI/1. h-1) in adult life.

Hypertension, oedema, and suppressed renin aldosterone system due to unsupervised salt administration

This paper describes an infant with gastroenteritis, who developed hypertension and oedema after administration of inaccurately prepared oral glucose salt solution. The renin aldosterone system was suppressed in this child and it was suggested that this may be a factor in the development of hypernatraemia when abnormal water losses occur in infants fed on hyperosmolar feeds. Unless salt can be given accurately in small amounts it may be safer to advise feeds of glucose only in infants with mild diarrhoea.