Pulsatile growth hormone secretion in peripubertal patients with chronic renal failure. Cooperative Study Group on Pubertal Development in Chronic Renal Failure

The pubertal growth spurt has been associated with changes of physiologic pulsatile growth hormone (GH) secretion, and abnormalities of the central regulation of GH release have been found by pharmacologic testing in patients with chronic renal failure. To assess the characteristics of GH pulsatility in chronic renal failure and their relationship to pubertal growth, we studied spontaneous nighttime GH plasma profiles in 80 patients (61 boys) aged 10 to 20 years receiving conservative treatment (n = 29) or dialysis (n = 18) or after renal transplantation (n = 33). Tanner genital stages 1 to 4 in boys and breast stages 1 to 3 in girls were represented. Growth hormone pulse analysis was performed by the PULSAR algorithm. Growth hormone concentration profiles were pulsatile in each patient. Growth hormone mean and baseline levels and pulse amplitudes were higher in patients receiving conservative or dialysis treatment than in patients who had undergone renal transplantation. Peak frequency was similar in all treatment groups in boys but higher in girls who had undergone transplantation than in girls receiving conservative or dialysis treatment. Growth hormone peak amplitude and mean levels were lowest in patients in late puberty. The physiologic elevation of GH amplitudes around midpuberty was observed in boys receiving conservative and dialysis treatment but not after transplantation. Growth hormone mean and baseline levels were positively correlated with plasma androgen levels in boys. Growth hormone peak amplitude was correlated with 6-month height velocity after transplantation but not in patients receiving conservative treatment or dialysis. A strong inverse relationship was observed between GH peak amplitude and corticosteroid dosage in patients undergoing transplantation. The lack of relationship between circulating GH levels and growth in patients receiving conservative or dialysis treatment is compatible with end-organ hyporesponsiveness to GH. Pubertal growth failure despite successful transplantation appears to be related to steroid-induced GH hyposecretion.     

Growth prognosis and growth after menarche in primary hypothyroidism.

The long term growth of 20 girls and nine boys with juvenile primary hypothyroidism was studied until they reached final height. At diagnosis the girls had a mean age of 8.8 years (range 3.0-13.0); mean bone age was 5.4 years. The mean age of the boys at diagnosis was 9.5 years (range 3.7-14.2); mean bone age was 6.3 years. The patients were treated with thyroxine 100 micrograms/m2/day and serum thyroxine concentrations were maintained in the normal range. During treatment the rate of skeletal maturation exceeded the change in chronological age. Initial mean height SD score for bone age before treatment in the girls was +0.59 and after 11 years of treatment fell to -0.55 Mean height SD score for bone age in the boys decreased from +1.6 to -0.87 during treatment. In the girls the onset of puberty was 1.2 years later than the normal population but the duration of puberty was reduced. Mean age (SD) of menarche was 13.8 (1.7) years. The pattern of growth in girls with treated hypothyroidism was abnormal as growth continued after menarche, at a time when normal girls have almost stopped growing. During the second year after menarche our patients still had a mean growth velocity of 4.1 cm/year. Our data suggest that juvenile primary hypothyroidism results in a permanent height deficit. In addition, there is a loss of the normal harmony between growth and sexual maturation in girls, despite adequate treatment, in that growth continues for much longer after menarche than in normal girls.     

Chlamydia trachomatis infection in infants: a prospective study.

In a prospective study of Chlamydia trachomatis infection in pregnancy, 198 mothers positive for chlamydial antigen were identified; the infants of 174 were followed for up to six months and C trachomatis was recovered in cell culture from 43 infants (25%). Conjunctivitis occurred in significantly more infants who were positive for C trachomatis (20 of 43, 47%) than in those who were negative (18 of 131, 14%). There were also significantly more lower respiratory tract infections among infants with positive cultures (six of 43, 14%, compared with three of 131, 2%). The chlamydial antigen enzyme linked immunosorbent assay (ELISA) was positive in 61 of 131 infants from whom C trachomatis was not recovered in cell culture. False positive results were usually associated with the isolation of Staphylococcus aureus from samples of pharyngeal aspirate. Our results confirm that C trachomatis infection is a common cause of neonatal conjunctivitis, and respiratory infection in the first few months of life, with an incidence of 8.2/1000 live births. Because the infection is easily treated by oral erythromycin, however, screening during pregnancy is not warranted.     

Egg and breast milk based nitrogen sources compared.

A nitrogen source based on egg protein (Vamin 9 glucose) and an alternative with an amino acid profile more similar to breast milk (Vaminolact), were compared in 14 parenterally fed infants. Subjects were randomly allocated to receive one or other amino acid solution, but were otherwise given identical diets. At the start of the study the two groups did not differ significantly in postconceptual age, postnatal age, or weight. Over a six day study period on a stable intake of intravenous nutrients there was no significant difference in growth or nitrogen retention between the two groups. Plasma amino acid profiles in those receiving Vamin 9 glucose, however, were frequently abnormal. Notably, mean concentrations of potentially neurotoxic phenylalanine and tyrosine were significantly higher (140% and 420%, respectively) in patients fed Vamin 9 compared with those given Vaminolact. An amino acid solution based on the composition of breast milk protein therefore brings plasma amino acid profiles during parenteral nutrition closer to those found in breast fed infants, and reduces in particular, the risks of hyperphenylalaninaemia and hypertyrosinaemia.     

The contribution of local distribution substations and associated area distribution system to personal exposure to power frequency magnetic fields

A number of epidemiological studies has shown a significant correlation between wire coding, magnetic fields and childhood cancer, although a more recent study has not [McBride et al. (1999) Am. J. Epidemiol. 149 (9), 831-842]. In the UK there is currently no equivalent to wire-codes and there is some uncertainty about the extent to which the UK medium-voltage electricity distribution systems contribute to personal exposure and how this compares with US overhead supply systems. Studies on four different area types were carried out to measure magnetic field intensities from typical electricity supply utility substations and cabling in the vicinity of domestic housing. Typically at distances of two metres from the substations mean magnetic field intensities were 20 nano teslas (nT) or less, increasing to 0.98 microT or less at the closest public access point. The mean magnetic field exposure level sampled around the four main test areas varied between 0.012 and 0.27 microT increasing to 0.30-0.80 microT at road junctions.     

The effect of cyproterone acetate on the growth of children with central precocious puberty

We have examined the growth and skeletal maturation of 19 children (6 male, 13 female) with central precocious puberty. The aetiology in nine patients (5 male, 4 female) was secondary to a hypothalamic hamartoma. Six children (2 male, 4 female) received no treatment whereas 13 children (4 male, 9 female) were treated with cyproterone acetate in a mean dose of 68 mg/m² per day (range, 34–260) for a mean duration of 4.5 years (range, 0.8–7.9). There was no significant difference between height SDS for bone age at the beginning and end of observation in either treated or untreated groups. No significant relationship between the mean dose of cyproterone acetate used and change in height SDS for bone age could be determined. We conclude that cyproterone acetate has no beneficial effect on the growth prognosis of children with central precocious puberty.Abbreviation GnRH gonadotrophin releasing hormone     

Patterns of growth in the hepatic glycogenoses.

Longitudinal growth data from 31 patients with hepatic glycogen storage disease (type I (8 patients), type Ib (three patients), type III (13 patients), and type IX (phosphorylase kinase deficiency) (7 patients) ) have been reviewed. All patients were below the mean for height at presentation; the mean height standard deviation scores were -2.13 (type I), -2.0 (type Ib), -2.4 (type III), and -1.6 (type IX). Untreated, most patients with type I and Ib grew slowly with no catch up growth but three patients with mild disease grew normally. Most children with type III disease grew at a normal velocity throughout childhood. Puberty was delayed and final height normal. Some of the children with type III and all of those with type IX had catch up growth throughout childhood. Intensive treatment of patients with severe forms of type I and Ib disease resulted in catch up growth, but this was not complete if the treatment was started late.