Regulation of insulin-like growth factor binding proteins in young growing animals by alteration of energy status.

The regulation of plasma insulin-like growth factor binding proteins (IGFBPs) by energy status has been assessed in 2-month-old pigs. Energy balance was modified by altering thermoregulatory demand and energy intake, with litter-mates being kept for several weeks at either 35 or 10 degrees C on a high (H) or low (L) level of food intake (where H = 2L); plasma samples were taken 20-24 h after the last meal. The two major forms of circulating IGFBP, as estimated by Western blot analysis, were identified putatively as IGFBP-2 and IGFBP-3 (relative molecular weights of 34 and 40-45 kDa respectively). There were significant differences in IGFBP profiles between the four treatment groups of 35H, 35L, 10H and 10L: the 40-45 kDa IGFBP (putative IGFBP-3) was elevated both in the warm and on a high food intake (P < 0.001), and there was a marked reciprocal relation between the 40-45 and 34 kDa IGFBPs. The relative concentration of the 34 kDa IGFBP (putative IGFBP-2) was greatest in the 10L and least in the 35H group. It is concluded that long-term alterations in energy balance, induced by changes in either intake or thermoregulatory demand, can significantly affect the plasma profile of IGFBPs during the first two months of life.

Dissociation between plasma concentrations of thyroxine and insulin-like growth factor-I.

The relation between plasma concentrations of thyroxine (T4) and insulin-like growth factor-I (IGF-I) has been examined in young, growing pigs under controlled conditions of energy intake. Compared with euthyroid controls, plasma levels of IGF-I were significantly elevated (P less than 0.005) both in hypothyroid animals on the same food intake and in hyperthyroid animals on double the food intake. There was however no increase in IGF-I in a hyperthyroid group on the control level of intake. Contrary to previous reports in which energy intake was not controlled, it is concluded that there is no simple correlation between plasma concentrations of T4 and IGF-I.

Variations in somatomedin-C/insulin-like growth factor-I associated with environmental temperature and nutrition.

The influences of environmental temperature and energy intake on plasma concentrations of somatomedin-C/insulin-like growth factor-I (IGF-I) have been investigated in young growing pigs. After 10 weeks acclimation, IGF-I was significantly greater at 35 than 10 degrees C (P less than 0.001) and on a high than a low energy intake (P less than 0.001). During the period 16-26 h after the last meal, there was a significant decline in IGF-I with time (P less than 0.01). These results can be explained partly in relation to differences in energy exchange in warm and cold environments and may also be related to changes in growth and thyroid hormones.

An enhanced chemiluminescent enzyme immunoassay for follicle stimulating hormone.

An enhanced chemiluminescent enzyme immunoassay for serum follicle stimulating hormone is described which involves sequential reaction of anti-follicle stimulating hormone antibody immobilised to the inside surface of an opaque microtitre plate with sample, monoclonal anti-alpha thyroid stimulating hormone antibody, and an anti-mouse IgG - horseradish peroxidase conjungate. Bound peroxidase activity was measured using a p-hydroxycinnamic acid enhanced chemiluminescent luminol-hydrogen peroxide reaction. The assay was sensitive (detection limit 0.01 mU/well) precise (intra-assay precision 2.5-8.1%, inter-assay precision 6.7-11.9%) and results obtained with this assay and a competitive radioimmunoassay were in good agreement (correlation coefficient 0.98).

An enhanced chemiluminescence enzyme immunoassay for serum oestradiol.

Oestradiol in serum was determined with a simple enhanced chemiluminescent enzyme immunoassay. The assay is based on oestradiol labelled with horseradish peroxidase and the IgG fraction of an oestradiol antiserum coated on a black polystyrene microtitre plate. The enzyme activity of bound label was determined using a p-hydroxycinnamic acid-enhanced chemiluminescent reaction. The assay was sensitive (1.8 fmol/well), precise (intra- and inter-assay CV 4-10% and 8-12%, respectively for sample concentration in the range 122-1330 pmol/L) and showed good agreement with conventional radioimmunoassays (r = 0.99).

Growth hormone deficiency and the measurement of somatomedin C/IGF-I: the influence of sexual maturation.

Fifty-nine short children 2-19 years, 25 females and 34 males, were studied for clinical and biochemical evidence of growth hormone deficiency (GHD). Group 1 (n = 32), mean height SDS -3.26 +/- 1.5, mean retardation of bone age 2 years, had a mean peak GH of 6.1 +/- 3.7 mIU/l during tests of GH release, and were classified as GHD. Group 2 (n = 27), had a mean height SDS of -2.65 +/- 1, mean bone age retardation of 1.7 years and had a mean peak GH during provocation tests of 24.3 +/- 11.1 mIU/l and were classified as non-GHD. Basal IGF-I concentrations were correlated with height and bone age, for both groups and for GHD children, with pubertal score. Neither peak GH values nor integrated GH concentrations in a provocative test were correlated with IGF-I values. The minimum IGF-I concentrations occurred at a bone age of 8 years, the reference point that was taken as the average expected time of maturational change. IGF-I concentrations rose in five GHD children when their bone age exceeded 8 years and when their free testosterone was greater than 10 pmol/l. Eighty-nine per cent of the GHD children with a bone age at or below 8 years were identified as GHD from their basal IGF-I values, but for all bone ages this fell to 62.5%. Basal IGF-I values appear to be less discriminatory for identification of GHD as sexual maturity and bone age advance.

Precocious and delayed sexual development in children.

A review is presented of tests used to diagnose either isosexual precocity or delayed pubertal development in children. The importance of auxological measurements is emphasised. Attention is drawn to the limitations of measuring basal or stimulated levels of LH, FSH and the sex steroids for the diagnosis of these conditions. The value of gonadotropin profiles is discussed for either diagnosis or for assessing the response to GnRH therapy in patients with either isosexual precocity or isolated gonadotropin deficiency. Examples are given of new therapeutic agents and procedures that are used to treat these two groups of patients. These include GnRH agonists for treatment of children with isosexual precocity either alone, or in combination with inhibitors of aromatase or C17-20 lyase enzyme activity in the biosynthesis of the sex steroids and pulsatile GnRH for the treatment of adolescents with gonadotropin deficiency.

Free cortisol and creatinine in urine of healthy children.

Cortisol and creatinine were measured in two consecutive overnight urine collections from 103 healthy school children, ages seven to 18.5 years. Mean cortisol and creatinine concentrations were respectively 194 nmol/L and 12.7 mmol/L. The data were statistically analyzed to simultaneously assess any effects of sex, age, weight, day of collection, and urine volume. Mean urine volume for boys exceeded that for girls, increased with body weight, and was greater on the second day of collection than on the first. Cortisol concentration was independent of sex, age, and weight, but decreased with urine volume. Boys excreted more cortisol than did girls, and the amount increased with urine volume. Creatinine concentration increased with weight, decreased with urine volume. Total creatinine increased with weight, was greater for boys than girls, and increased with urine volume. The cortisol/creatinine ratio was valueless as an index of adrenocortical status.

Should we screen for congenital adrenal hyperplasia? A review of 117 cases.

A total of 117 patients with congenital adrenal hyperplasia who were under the care of paediatricians at Birmingham Children's Hospital between 1958 and 1985 were reviewed retrospectively. There were 47 boys (40%) and 70 girls (60%); 30 of the 47 boys (64%) and 38 of the girls (58% of the 66 whose salt state was known) were salt losers. In all salt losers the condition was diagnosed before the age of 6 months, 90% of the diagnoses being made during the first month. The ratio of boys to girls, the distributions of salt losers to non-salt losers, and the age at diagnosis were studied in relation to the year of birth. Early diagnosis was found to be more common in children born after 1970 due partly to the introduction of a method of assaying the concentration of 17 alpha-hydroxyprogesterone in serum, partly to an increase in the number of paediatricians in the West Midlands, and partly to the appointment of a paediatric endocrinologist. A neonatal screening programme does not seem to be necessary.

Observations on the role of GH/IGF-1 and sex hormone binding globulin (SHBG) in the pubertal development of growth hormone deficient (GHD) children.

SHBG concentrations in GHD and non GHD children of both sexes were studied in relation to their weight and androgen status. SHBG was inversely related to age in short and control children, but not for GHD. Correction for body weight restored the inverse relationship in these children and improved the correlation for the other groups. DHAS concentrations were similar in GHD and short children, suggesting GH per se does not influence adrenal androgen synthesis. The mean free testosterone in GHD children 12.7 pmol/L, was similar to that in short children, 14.3 pmol/L, and lower than controls 21.2 pmol/L, but consistent with their pubertal status. The linear regression of SHBG on IGF-1 was r = -0.605 (P less than 0.01). It was postulated that IGF-1 and free testosterone may regulate SHBG synthesis. Administration of native and synthetic GH to prepubertal GHD children lowered SHBG without a significant change in TBG, albumin or free testosterone. The fall in SHBG concentration after HGH in GHD children is suggested as a selective mechanism which may lead to improved pubertal development.

Pre-pubertal gynaecomastia as the presenting feature of late-onset 21-hydroxylase deficiency.

We describe an 8-year-old boy with pre-pubertal gynaecomastia as the presenting feature of late-onset 21-hydroxylase deficiency, an association not previously reported. Although absolute oestrogen levels were not higher than previously described in 21-hydroxylase deficiency, the gynaecomastia may have arisen through a relative disproportion of the C18 to C19 steroids.

An enhanced chemiluminescence enzyme immunoassay for serum progesterone.

A competitive enhanced luminescent enzyme immunoassay for serum progesterone is described, which is based on a 11 alpha-hydroxyprogesterone 11-hemisuccinyl-horseradish peroxidase conjugate and a black polystyrene microtitre plate sensitised with anti-progesterone IgG. Bound label was determined using a mixture of 4-iodophenol, luminol and peroxide, and the light emitted from the wells of the plate quantitated using a luminescent plate reader. The assay was sensitive (detection limit 0.5 pg), precise (CV 2.7 - 9.0% in the concentration range 4.3-67.7 nM) and showed good correlation (r = 0.99) with a conventional radioimmunoassay.

Plasma renin activity in the management of congenital adrenal hyperplasia.

Fourteen children with salt losing and five children with non-salt losing congenital adrenal hyperplasia were studied. Venous samples were collected for measurement of plasma renin activity, serum 17 alpha-hydroxyprogesterone, testosterone, sodium, and creatinine. Overnight urinary sodium and creatinine excretions were measured after collection on an outpatient basis. Eight 'salt losers' had a raised plasma renin activity despite mineralocorticoid treatment, as did one 'non-salt loser'. Six of the children in whom clinical and biochemical control was inadequate, including the 'non-salt loser', had an increase in the dose of fludrocortisone. When the investigations were repeated one month later, a fall in plasma renin activity accompanied by a fall in 17 alpha-hydroxyprogesterone in all but one patient were found. The dose of mineralocorticoid may be as critical as the dose of glucocorticoid in the management of congenital adrenal hyperplasia, and regular determination of plasma renin activity should be made, particularly if clinical control is difficult.

A screening method for measuring somatomedin B protein binding in serum from children with growth retardation.

A simple method which uses 100 microliter serum has been developed to measure the binding of somatomedin B (SMB) to protein in serum from normal children, adults, and patients with growth hormone deficiency. 125I-labelled SMB was used as binding ligand. The correlation between the binding of label by the proposed procedure and by an immunoelectrophoretic technique was acceptable (r = 0.73; P less than 0.02). The mean percentage of label bound to protein in serum from patients with deficiencies of growth hormone or other trophic hormones was significantly (P less than 0.001) lower than that for controls. The physicochemical characteristics of a specific binding-protein suggested that a protein with low capacity (160 pmol/l) and low Ka (4.37 X 10(6) l/mol was present in serum, in addition to a high concentration of alpha globulin(s) which also bound 125I SMB.

Congenital adrenal hyperplasia in a 66-year-old female.

A 66-year-old genotypically female patient was reared as a man. Investigations showed a partial adrenal 21-hydroxylase deficiency, and pituitary gonadotrophin secretion typical of a post-menopausal woman.

Oestrogen-gonadotrophin feedback mechanisms in the puerperium.

The effect of oestradiol benzoate on serum gonadotrophin concentrations before and after LHRH administration was studied in lactating and non-lactating women at 3 and 6 weeks post-partum. Except in the non-lactating women at 6 weeks, basal serum FSH concentrations were suppressed by oestrogen. There were no significant changes in basal concentrations of LH after oestrogen in the lactating women in either the 3- or 6-week studies. Individual increases in the basal LH concentrations in two out of six non-lactating subjects in the 6-week study occurred but overall there were no significant changes. In the 6-week study amplification of the LH response to LHRH was found in both groups, the effect being significantly greater in the non-lactating women. Overall FSH responses were also significantly different in the two groups, being suppression in those lactating ad amplification in those not lactating. The LH/FSH ratios following LHRH administration in the 6-week non-lactating study were similar to those seen in the early follicular phase in regularly menstruating subjects. The basal ratios in the lactating subjects were, however, significantly less than those seen in the non-lactating subjects both at 3 and 6 weeks. This difference was associated with the relative enhancement of LH release in non-lactating subjects and enhancement of FSH release in those lactating. Taken together the results indicate the presence of an intact negative feedback of oestrogen on gonadotrophin release in both groups being enhanced at 6 weeks post-partum in the lactating subjects; also in the lactating subjects at 6 weeks there was less amplification by oestrogen of the responsiveness of the anterior pituitary to LHRH. At 6 weeks, however, in the non-lactating group these responses were similar to those seen in normal regularly menstruating subjects. These dynamic endocrine studies suggest a possible hypothalamic-pituitary mechanism which may help to explain the delayed return of ovulatory cycles in lactating women.