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Biomedical subjects

C T Cowell

Publications and source records attributed to C T Cowell.

At least 55 records · Page 3Linked to original sources
PubMed1995

Volumetric bone mineral density--a potential role in paediatrics.

The use of areal bone mineral density (aBMD) in paediatric populations has aroused some concern, as it fails to take the age-related increase in bone thickness into account. We have developed a measure of true bone density, volumetric bone mineral density (vBMD), which is independent of age and height. In order to examine the relationship between growth parameters, aBMD and vBMD, we studied patients with phenylketonuria (PKU, n = 40), chronic renal failure (CRF, n = 27) and chronic asthma (n = 19). aBMD of the femoral neck and the mid-femoral shaft was measured using dual energy X-ray absorptiometry (DXA), vBMD was calculated on the basis of values of bone mineral content and bone dimension provided by DXA, with the assumption that both sites are cylinders. aBMD and vBMD were then compared with the normal reference, expressed as a standard deviation score (SDS). aBMD and vBMD were normal in the femoral neck region of the PKU group, but aBMD, either standardized for age or for height, was low in the femoral shaft region (p < 0.01). In the CRF group, profound growth retardation was seen (mean height SDS, -3.2) and aBMD and vBMD were both low in the femoral shaft region but not in the femoral neck. In the asthma group, aBMD for age was low at both sites, but vBMD did not differ from that seen in normal individuals. We conclude that the true vBMD provides a different interpretation of bone density compared with aBMD and requires further evaluation in paediatrics because of its age and height independence.

Absorptiometry, Photon↗
PubMed1994

Bone mineral density of total body, spine, and femoral neck in children and young adults: a cross-sectional and longitudinal study.

Bone mineral density (BMD) of total body (TBMD), lumbar spine (L2-4), and femoral neck was measured in 266 normal subjects (136 males) aged 4-27 years (mean 13 years) using dual-energy x-ray absorptiometry (DXA). BMD of all sites increased significantly with age until 17.5 years in males and 15.8 years in females, except for femoral neck BMD in females, which peaked at age 14.1 years. Males had higher peak TBMD, which was attributed to greater weight and lean tissue mass. In contrast, despite a later timing, peak L2-4 BMD in males was not different from that in females. Before peak BMD, weight was the best predictor of TBMD and L2-4 BMD in both sexes (r2 ranged from 0.77 to 0.88), whereas femoral neck BMD was predicted equally by height and weight. Longitudinal information collected from 53 (25 boys) of these children, aged 4-16.9 years, showed that the average annualized gain in TBMD was 0.047 g/cm2 for boys and 0.039 g/cm2 for girls. No significant difference in the association between age and BMD (slopes) was found between cross-sectional and longitudinal data for either sex. We conclude that the timing for peak BMD was consistent for total body, lumbar spine, and femoral neck for each sex. The earlier peak BMD in females is most likely related to earlier puberty. The cross-sectional normative data of this study are useful in serving as a standard for serial assessment in health and disease states.

Absorptiometry, Photon↗
PubMed1994

Insulin-resistant diabetes during growth hormone therapy in a child with SHORT syndrome.

We report the case of a 13-year-old boy with SHORT syndrome, including lipoatrophy and insulin resistance, who developed diabetes mellitus while receiving growth hormone therapy. The diabetes persisted after cessation of exogenous growth hormone but oral hypoglycaemic therapy was successful and could be discontinued eight months later.

Abnormalities, Multiple↗
PubMed1994

Changes in body composition and bone density after discontinuation of growth hormone therapy in adolescence: an interim report.

Growth hormone deficiency (GHD) in adults and children is associated with decreased lean tissue mass (LTM), increased fat mass and reduced bone mineral density (BMD). The changes in BMD and body composition, 6 and 12 months after ceasing GH treatment, were assessed using dual-energy X-ray absorptiometry in eight patients with GHD (age range, 13.8-17.5 years). Seven age-matched normal subjects who had completed growth were assessed at 0 and 12 months. Total body BMD was low at baseline (p < 0.05) in patients with GHD compared with the predicted values based on sex-specific regression equations, with height, weight and age taken into account. Total body, lumbar spine and femoral neck BMD increased in the patients and controls at 12 months. LTM decreased significantly by a mean of 1.37 kg in the patients with GHD at 12 months whereas there was a non-significant increase in LTM in the control group. The percentage of body fat increased in all patients with GHD at 6 and 12 months, from 27.2 +/- 11% (mean +/- SD) at baseline to 32 +/- 9.9% at 12 months (p = 0.009). There was no significant increase in mean percentage body fat in the control group. The ratio of android (trunk):gynoid (legs) fat was calculated using default settings of dual-energy X-ray absorptiometry. The mean android:gynoid fat ratio increased, though non-significantly, in patients with GHD at 12 months, with 6 of 7 showing an increase; no change was observed in the control group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Combined therapy with growth hormone and oxandrolone in adolescent girls with Turner syndrome.

Five adolescent girls with Turner syndrome (mean age 13.9 years, mean bone age 12.0 years) were treated with both recombinant human growth hormone (rhGH) and oxandrolone for 2 years with an average increment in height of 13.4 cm. The mean bone age advanced by only 1.2 years, providing an increase in the mean estimated mature height of 9.2 cm. We conclude that rhGH and oxandrolone benefit older teenagers with Turner syndrome because of an increased growth rate with slow progression of skeletal maturation.

Adolescent↗
PubMed1993

Growth in children with X-linked hypophosphataemic rickets.

Currently, X-linked hypophosphataemic rickets (XLHR) is most commonly treated with a combination of phosphate and vitamin D, but there is conflicting evidence about the effects of this treatment on linear growth. In all, 25 patients with XLHR (current age range, 4.1-22.1 years; median, 8.2 years) were studied to determine whether there was any improvement in height SDS during treatment. The duration of therapy was 2.9-15.0 years (median, 5.7 years). Measurements before the age of 2 years or after the onset of puberty were excluded to remove the effects of measurement difficulties in small infants and of variation in pubertal timing. The growth of these patients was compared with a similar group of untreated historical controls. Patients treated with calcitriol and phosphate for at least 2 years before the onset of puberty (n = 22) had a significantly better mean height SDS than the historical controls (-1.23 compared with -2.05 for the historical controls; p = 0.02). Among patients treated with calcitriol and phosphate for at least 2 years (n = 21), the change in height SDS had a positive correlation with the duration of therapy (r = 0.51; p = 0.02). The growth of children with XLHR treated with combination therapy was thus significantly better than that of historical controls.

Adolescent↗
PubMed1992

Pituitary gigantism.

A case of pituitary gigantism resulting from a pituitary adenoma which secreted growth hormone is described. The patient was successfully treated by surgery, which led to the normalisation of endogenous growth hormone secretion. An acceptable final height was achieved with high dose intramuscular testosterone treatment.

Adenoma↗
PubMed1991

Effects of therapy in X-linked hypophosphatemic rickets.

BACKGROUND: Patients with X-linked hypophosphatemic rickets, which is clinically manifested by growth failure and bowing of the legs, are usually treated with phosphate and a vitamin D preparation. However, the efficacy of this treatment has been disputed, and nephrocalcinosis is a recognized complication of therapy. METHODS: We studied 24 patients with X-linked hypophosphatemic rickets (9 boys and 15 girls) ranging in age from 1 to 16 years (median, 5.3). The duration of combination therapy ranged from 0.3 to 11.8 years (median, 3.0). We measured height as a standard-deviation (SD) score (the number of SDs from the mean height for chronologic age). Measurements made before the age of two years or after the onset of puberty were excluded. We compared the results with those reported in 1971 for 16 untreated prepubertal Australian patients. We also determined the severity of nephrocalcinosis (on a scale of 0 to 4, with 0 indicating no abnormalities and 4 stone formation) with renal ultrasonography and whether it could be related to the dosage of phosphate or vitamin D or to other factors. RESULTS: Patients treated for at least two years before the onset of puberty (n = 19) had a mean height SD score of -1.08, as compared with -2.05 in the untreated historical controls. The 13 patients who had been treated with calcitriol and phosphate for at least two years had an increase in the mean height SD score of 0.33, from -1.58 to -1.25 (95 percent confidence interval, 0 to 0.67; P = 0.05). Nineteen of the 24 patients (79 percent) had nephrocalcinosis detected on renal ultrasonography. The grade of nephrocalcinosis was significantly correlated with the mean phosphate dose (r = 0.60, P = 0.002), but not with the dose of vitamin D or the duration of therapy. All patients had normal serum creatinine concentrations. CONCLUSIONS: Therapy with calcitriol and phosphate may increase the growth of children with X-linked hypophosphatemic rickets. Nephrocalcinosis in these children represents a complication of therapy and is associated with the dose of phosphate received.

Body Height↗
PubMed1991

Effect of obesity on endogenous secretion of growth hormone in Turner's syndrome.

Nocturnal growth hormone secretion over a 12 hour period was assessed at 20 minute intervals in 25 prepubertal subjects with Turner's syndrome and 11 normal prepubertal girls of short stature to try and elucidate the relationship between body weight and endogenous secretion of growth hormone in Turner's syndrome. There were no differences in mean growth hormone concentration, age, height, or growth velocity between the two groups. There was an age related decline in mean growth hormone concentration in patient's with Turner's syndrome in contrast to the age related increase in controls. Mean percentage of ideal body weight was significantly higher in the Turner's syndrome group than among controls and it increased with age. There was a strong inverse relationship between mean growth hormone concentration and percentage of ideal body weight in those with Turner's syndrome. Covariate analysis of the multiple linear regression of mean growth hormone concentration on age and percentage of ideal body weight in Turner's syndrome indicated that percentage of ideal body weight had a significant effect on endogenous secretion of growth hormone when age was held constant, but not the other way round. We conclude that the age related decline in endogenous secretion of growth hormone in Turner's syndrome is partly the result of increasing body weight with age. The significant influences of biological variables such as age and body weight in the interpretation of measurements of endogenous secretion of growth hormone in Turner's syndrome should be emphasised.

Adolescent↗
PubMed1991

Insulin-like growth factor and growth hormone secretion in juvenile chronic arthritis.

Insulin-like growth factor (IGF-1) concentrations were determined in a series of 23 children with juvenile chronic arthritis in conjunction with anthropometric assessment. When standardised z scores were used significant decreases in height and weight were shown in comparison with the normal age/sex matched means. Severe growth disturbance was seen, particularly in those with prolonged disease duration, which was independent of corticosteroid treatment, indicating disease activity itself is a major factor in the growth retardation. Eight children had low IGF-1 z scores--that is, less than -2.00 from age/sex matched mean. Low IGF-1 z scores were associated with low weight z scores but not with low height z scores. Overnight growth hormone secretory profiles were determined in 10 patients, including seven with low IGF-1, and showed generally normal secretion in all but one patient, who subsequently attained normal concentrations coincident with catch up growth. Increased pulse frequency of overnight secretion was commonly seen. Low IGF-1 concentrations probably result from varying factors, particularly nutritional, but do not reflect marked endocrinological abnormalities in most patients.

Adolescent↗
PubMed1990

Luteinizing hormone-releasing hormone analogue (Buserelin) treatment for central precocious puberty: a multi-centre trial.

A multi-centre open trial of Buserelin, a luteinizing hormone-releasing hormone (LHRH) analogue, was conducted in 13 children with central precocious puberty. Eleven children (eight girls and three boys), aged 3.4-10.2 years at commencement, completed the required 12 month period of treatment. Initially all patients received the drug by intranasal spray in a dose of 1200 micrograms/day, but by the end of the 12 month period two were having daily subcutaneous injections and three were receiving an increased dose intranasally. The first month of treatment was associated in one boy with increased aggression and masturbation, and in the girls with an increase in the prevalence of vaginal bleeding. Thereafter, however, both behavioural abnormalities and menstruation were suppressed. Median bone age increased significantly during the study, but without any significant change in the ratio of height age to bone age. The median predicted adult height for the group therefore did not alter significantly over the twelve months of the study. Buserelin treatment caused a reduction in the peak luteinizing hormone and follicle-stimulating hormone (FSH) responses to LHRH, mostly to prepubertal levels, and also suppressed basal FSH. In the first weeks of treatment, the girls' serum oestradiol levels rose significantly and then fell to prepubertal or early pubertal levels. A similar pattern was seen for serum testosterone levels. Serum somatomedin-C levels, however, showed little fluctuation over the course of the study. Buserelin treatment was safe and well accepted, and offers the promise of improved linear growth potential in precocious puberty.

Administration, Inhalation↗
PubMed1990

Effects of growth hormone in short, slowly growing children without growth hormone deficiency. Australasian Paediatric Endocrine Group.

The aim of the study was to measure the real effect of growth hormone (GH) treatment compared to the effect of placebo, since a placebo effect has been shown in other studies involving interventional growth therapy. Changes in height velocity and insulin-like growth factor I (IGF-I), relative to pretreatment variables, were examined during a 12-month, double-blind study.

Adolescent↗
PubMed1989

Patterns of hospitalisation in a paediatric diabetes clinic in Sydney.

The hospital notes of all children with diabetes admitted to the Children's Hospital (both newly diagnosed and subsequent admissions) for the period 1985-1987 were examined. The information collected included basic demographic data, number of bed-days per admission, and reasons for admission. The direct cost of a bed-day and an admission for diabetes in this hospital were calculated. The median duration of an admission at diagnosis was 12 days, and of a subsequent admission 7 days. The proportion of total admissions to the Children's Hospital in 1987 which were due to diabetes (post diagnosis) was eight times the prevalence of IDDM in the 0-14-year population. In 1987, 5.5% of the diabetic patients (excluding new cases) aged 0-19 years and registered with this Diabetes Unit were admitted to hospital. Most of these admissions were for poor control, and were thus potentially preventable. The age group most at risk for admission due to ketoacidosis was the 10-14-year group. The cost of a diabetic bed-day was $Aust 295, average cost of an admission at diagnosis $Aust 3660, and of a post-diagnosis admission $Aust 2680. Thus, even in this young age group there is considerable morbidity due to diabetes, most of which can probably be prevented.

Adolescent↗
PubMed1989

Carbohydrate metabolism on high dose growth hormone therapy in children treated for leukaemia.

The effect on carbohydrate metabolism of a high dose growth hormone (GH) regimen (1.2 U/kg per week) was assessed on 24 children who had previously been treated for leukaemia. Sixteen patients received high dose GH and eight patients received a conventional dose of GH (0.6 U/kg per week). Oral glucose tolerance tests (OGTT) were performed at baseline and after 3 months of treatment with GH. For the entire group between 0 and 3 months, there was a significant increase in mean (and standard deviation) fasting plasma glucose (0.3 +/- 0.6 mmol/L), fasting insulin level (11 +/- 26 mU/L), and 2 h insulin level (20 +/- 40 mU/L). One patient, who received a conventional dose of GH, developed substantial carbohydrate intolerance. For the entire group, there was no change in response to a carbohydrate load at 3 months as measured by the area under the plasma glucose or insulin curve. There was no significant difference between conventional and high dose groups at 3 months as assessed by these parameters. This study demonstrates that a higher dose of GH may be used in these children in an attempt to improve their final height, without increased risk of carbohydrate intolerance in the short term.

Blood Glucose↗
PubMed1989

Congenital adrenal hyperplasia family studies using the short ACTH test.

Because of the increasing use of 17-hydroxyprogesterone (17OHP) levels with the short adrenocorticotrophic hormone (ACTH) test in the detection of 21-hydroxylase deficiency, the diagnostic efficiency of the test was evaluated in patient and family studies of congenital adrenal hyperplasia due to 21-hydroxylase deficiency and of congenital adrenal hyperplasia due to 11-hydroxylase (11OH) deficiency (the latter disorder now overlaps basally with the milder non-classical 21-hydroxylase deficiency [NC-CAH]). Stimulated 17-hydroxyprogesterone level (17OHP30), 17-hydroxyprogesterone increase (delta 17 OHP) and the ratio 17-hydroxyprogesterone increase to cortisol increase (delta 17OHP/delta cortisol) were the parameters from the short ACTH test derived for assessment. 17-OHP30 provided complete differentiation of NC-CAH from the controls and heterozygotes, but overlap between NC-CAH and 11-OH occurred. Complete differentiation of NC-CAH from 11-OH was achieved using delta 17OHP. The heterozygotes showed best differentiation from the controls using delta 17OHP/delta cortisol with a diagnostic accuracy of 70%, however marked overlap of heterozygotes and NC-CAH with 11-OH was found. The short ACTH test proved to be a valuable technique with the further detection of homozygotes (n = 3) and heterozygotes (n = 5) in the 13 families studied. However, when interpreting the short ACTH test a careful choice of parameters should be made. It should be kept in mind that mild NC-CAH patients can only be differentiated from 11OH patients by using delta 17OHP.

17-alpha-Hydroxyprogesterone↗