Growth and the growth hormone axis in prepubertal children with asthma.

To determine the influence of asthma and its treatment with inhaled corticosteroids on growth, linear growth velocity, and the growth hormone axis in prepubertal children, we performed a longitudinal study for 12 months in 56 children with asthma, aged between 4.4 and 11.7 years. Height, weight, skin-fold thickness, and lung function were measured every 3 months and bone age at entry to and exit from the study. A 24-hour serum growth hormone concentration profile and fasting insulin-like growth factor I levels were measured halfway through the year. Seventy-four percent of boys and 62% of girls had heights below the 50th percentile. Growth velocity in the nonsteroid-treated control group (n = 13) was normal; 10 of 20 children taking beclomethasone grew slowly (14/20 used a dry powder device), and 4 of 19 children taking budesonide grew slowly (15/19 used a spacer). Three of four children using inhaled steroids and prednisolone grew slowly. In none of the treatment groups were measures of growth hormone secretion or levels of radioimmunoassayable serum insulin-like growth factor I affected. We conclude that slow growth in steroid-treated children with asthma does not appear to be associated with major perturbations in the growth hormone axis.

Increased energy expenditure in a patient with diencephalic syndrome.

Total energy expenditure, measured in an infant with diencephalic syndrome with doubly labeled water, was 30% to 50% higher than that reported for other healthy infants whose energy expenditure was measured by the same technique and 13% higher than the patient's energy intake. This result suggests that the weight loss and cachexia of the diencephalic syndrome are the result of abnormally increased energy expenditure.

Bioavailability of dietary urea nitrogen in the infant.

Because the human body has no enzymes capable of hydrolyzing urea, nitrogen from this source becomes bioavailable only by release of ammonia from urea by bacterial hydrolysis in the intestines, with subsequent absorption and utilization of ammonia. To explore extent to which urea ingested in milk becomes bioavailable, we fed di-15N-urea (both nitrogen atoms in the form of the stable isotope 15N) and determined urinary excretion of di-15N-urea (excreted without having become bioavailable) and mono-15N-urea (urea containing only one atom of 15N and therefore reflecting excretion of absorbed ammonia). The largest percentage of the ingested di-15N-urea was excreted promptly in the urine still in the form of di-15N-urea. We conclude that most of the urea ingested by a normal infant is not bioavailable.

In vitro measurement of antithyroid compounds and environmental goitrogens.

A specific, sensitive, and reproducible in vitro assay for antithyroid compounds and environmental goitrogens has been used to investigate antithyroid activity (AA) in small samples of water supplying 15 localities in endemic and nonendemic goiter areas of western Colombia. A significant positive correlation was observed between goiter prevalence and AA in water collected from the pipelines of these localities. Samples at the water source showed only borderline significance. No significant correlation was observed in waters between AA and total hardness (ppm) or concentrations of Ca, Mg, sulfates, chlorides, silicates, nitrates, and iodine. AA was also demonstrated by this in vitro assay in well water previously shown experimentally to be goitrogenic and that supplied the endemic goiter district of Candelaria town in western Colombia. In contrast, water from the well supplying the area of lower endemicity was found to possess little AA. These results provide experimental support for epidemiological observations that demonstrate a relationship between the sources of drinking water and goiter prevalence rates, and are consistent with previous findings indicating that organic antithyroid compounds contaminate water supplies in areas where goiter persists despite adequate iodine supplementation.