Subclinical hypothyroidism and cardiovascular risk.
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Cardiovascular Diseases↗
Biomedical subjects
J U Weaver
Publications and source records attributed to J U Weaver.
Design of new questionnaires to measure quality of life and treatment satisfaction in hypothyroidism.
INTRODUCTION: This paper reports work undertaken to design two new condition-specific questionnaires for use in hypothyroidism: the Underactive Thyroid-Dependent Quality of Life Questionnaire (ThyDQoL) and the Underactive Thyroid Treatment Satisfaction Questionnaire (ThyTSQ). METHODS: Semistructured interviews exploring quality of life (QoL) and experiences of treatment were conducted with 30 women and 8 men with hypothyroidism, (mean age, 51.9; range, 29-79 years), 37 of 38 treated with thyroxine, recruited from hospital clinics and primary care. RESULTS: Despite thyroxine treatment, most interviewees reported negative impact of hypothyroidism on QoL, particularly on energy, physical capabilities, motivation, physical appearance, and weight. The newly designed ThyDQoL has 18 domains covering these and other aspects of life affected by hypothyroidism. It is an individualized measure of patients' perceived impact of hypothyroidism on their QOL, which takes into account the importance of personally applicable life domains to the patient. A 7-item measure of satisfaction with current treatment was designed (ThyTSQ-Present) but interviews also indicated the need for a separate 4-item section measuring satisfaction with past treatment around the time of diagnosis (ThyTSQPast). CONCLUSIONS: The ThyDQoL and ThyTSQ questionnaires have good face validity and content validity for adults with hypothyroidism. They are now ready for use in clinical research and psychometric evaluation.
Adult↗
Nateglinide alone or with metformin safely improves glycaemia to target in patients up to an age of 84.
AIM: To assess the effect of nateglinide on efficacy [fasting plasma glucose (FPG), postprandial plasma glucose (PPG) plasma glucose and HbA1c], tolerability and safety in patients with type 2 diabetes mellitus (T2Dm) on diet alone or on metformin in subjects up to an age of 84. METHODS: In an open-labelled 12-week, parallel study of 358 patients, aged 35-84 years with T2Dm, nateglinide was given as either monotherapy in patients previously on diet alone or low-dose sulfonylureas, which required washout before the study (group 1), or as an addition therapy in patients on steady dose of metformin (group 2). Nateglinide 120 mg was given before main meals. HbA1c, FPG and PPG values were taken at the time of breakfast at the beginning and the end of the study. RESULTS: HbA1c fell by a mean of 0.83%, 95% confidence interval (CI) (-0.97, -0.69) (p < 0.001) in group 1, and 0.67%, 95% CI (-0.77, -0.58) (p < 0.001) in group 2. There was a significant improvement in PPG in group 1 by a mean reduction of -3.47 mmol/l, 95% CI (-4.08, -2.87) (p < 0.0001) and in group 2 of -2.41 mmol/l, 95% CI (-2.84, -1.99) (p < 0.0001). There was an improvement in FPG of -1.2 mmol/l, 95% CI (-1.49, -0.81) (p < 0.0001) and -0.8 mmol/l, 95% CI -(1.07, -0.53) (p < 0.0001) in group 1 and 2 respectively. 44% of patients in group 1 and 34% in group 2 achieved target of HbA1c < 7.0 and 66% in group 1 and 59% in group 2 achieved of HbA1c < 7.5%. Only one subject on nateglinide and metformin was withdrawn due to the side effect of hypoglycaemia. No patient required third-party assistance nor was admitted to hospital due to hypoglycaemia. CONCLUSION: These data demonstrate that nateglinide is a safe and effective agent in treatment to target in patients with T2Dm up to an age of 84 years.
Adult↗
Serum fructosamine as a marker of 5-year risk of developing diabetes mellitus in patients exhibiting stress hyperglycaemia.
AIMS: We examined whether the level of random serum glucose (RSG) in subjects exhibiting stress hyperglycaemia is a useful marker of the future risk of developing diabetes mellitus (DM), and whether serum fructosamine is of any additional value. METHODS: All non-diabetic adults attending Accident and Emergency in 1994-1995, who had venesection, were studied. Serum fructosamine and RSG were routinely measured in all such patients. Using the laboratory biochemistry database the number of subjects with stress hyperglycaemia (RSG > 11.1 mmol/l) was determined, and their corresponding fructosamine values were recorded. The number of subjects who developed DM over the following 5 years was determined. RESULTS: Three hundred and seventeen patients had stress hyperglycaemia, and follow-up data were available on 224 patients. Of these patients, 63 (28%) had developed DM over the 5 years follow-up period. RSG and fructosamine levels at baseline of patients subsequently developing DM were (mean +/- sd (range)) 16.7 +/- 7.0 (11.2-55.0) mmol/l and 3.3 +/- 0.6 (1.3-4.5) mmol/l, respectively. The patients who did not develop DM had a similar baseline RSG, 15.9 +/- 3.3 (11.2-30.6) mmol/l; P = 0.170, but lower baseline fructosamine, 2.4 +/- 0.4 (1.6-3.8) mmol/l; P < 0.001. Receiver-operating characteristics showed that a serum fructosamine > or = 2.8 mmol/l was a useful marker of the future risk of DM (75% sensitivity, 74% specificity, 53% positive and 88% negative predictive power). CONCLUSIONS: The level of RSG in stress hyperglycaemia does not predict the future development of DM. Raised serum fructosamine is a more useful marker of future DM risk than RSG alone. Further prospective studies are needed.
Adolescent↗
Severe hyponatraemia: investigation and management in a district general hospital.
AIMS: To study the incidence, investigation, and management of severe hyponatraemia (serum sodium < 120 mmol/litre) over a period of six months in a district general hospital. METHODS: The laboratory computer was used to identify all inpatients who had a serum sodium concentration of less than 120 mmol/litre over a six month period. The records of these patients were reviewed for the relevant demographic, clinical, and laboratory data, in addition to diagnosis, treatment, and outcome of hospitalisation. RESULTS: Forty two patients were studied, with a female to male ratio of 2 : 1. Nine patients had central nervous system symptoms, and four of these patients died in hospital. Only 14 patients had their urinary electrolytes and/or osmolality checked. A diagnosis of syndrome of inappropriate secretion of antidiuretic hormone (SIADH) was mentioned in eight patients, sometimes without checking their urinary electrolytes or osmolality. Twenty one patients died in hospital. The patients who died did not have lower serum sodium values or a higher rate of correction of hyponatraemia, but they all suffered from advanced medical conditions. CONCLUSIONS: The possible cause of hyponatraemia should always be sought and that will require an accurate drug history, clinical examination, and assessment of fluid volume, plus the measurement of urinary electrolytes and osmolality in a spot urine sample. The diagnosis of SIADH should not be confirmed without the essential criteria being satisfied. The current or recent use of diuretics is a possible pitfall in the diagnosis of SIADH. The rate of serum sodium correction of less than 10 mmol/day is probably the safest option in most cases.
Adult↗
Influence of growth hormone on accretion of bone mass.
Growth hormone (GH) exerts important influences on bone metabolism during lifespan. During childhood, GH is a major determinant of acquisition of bone mass and in adult life, GH partly determines the rate of bone remodelling and therefore influences maintenance of bone mineral density (BMD). Insights into the importance of GH in these respects may be obtained by studies of BMD and indices of bone remodelling in GH deficiency (GHD) of adult-onset and childhood-onset. Adult-onset GHD, usually accompanied by other features of hypopituitarism, may be associated with osteopenia and an increased fracture risk. Postulated mechanisms include GHD and gonadal steroid deficiency of unknown duration; glucocorticoid and thyroxine replacement do not appear to exert a major role. GH replacement in adult-onset GHD results in an early increment in indices of bone remodelling which persists for up to 5 years; BMD increases by 0.5-1.0 SD in males and stabilizes in females over this time period. In adolescents with GHD who traditionally discontinue GH at completion of linear growth, BMD is substantially lower than peak bone mass for a young adult population. Studies addressing the effects of continuation of GH after achievement of final height are currently underway and will provide insights into the possible need to continue GH into adult life. Such studies may confirm a role for GH in promoting continued accrual of bone mass and thereby demonstrate that cessation of GH at achievement of final height, by limiting peak bone mass, may predispose to clinically significant osteoporosis in later life. In addition to the potential importance of GH for achievement of peak bone mass, there may be a superimposed accelerated loss of BMD with advancing age similar to the situation observed in adult-onset GHD. To date, this has been difficult to assess in adult GHD of childhood-onset because the relative contributions of low peak bone mass and increased loss of bone in later life could not be distinguished.
Adolescent↗
Comparison of two direct methods for HDL cholesterol measurement with an indirect precipitation method in diabetic patients.
The conventional precipitation method for measuring HDL cholesterol involves a centrifugation step which prevents automation of the method. Several methods have been introduced for measuring HDL cholesterol without the need for a centrifugation step. These new methods are therefore automatable and can process a large number of samples in a short period of time. Measuring HDL cholesterol is an important aspect of management of diabetes mellitus. In this study, we compared 2 direct methods for measuring HDL cholesterol with a conventional precipitation technique in 63 patients with either Type 1 or Type 2 diabetes mellitus. Both direct methods showed acceptable precision but they both showed positive bias compared to the conventional precipitation method. The greatest degree of bias occurs at low HDL cholesterol levels, which are more important for Type 2 patients. Such differences may affect cardiovascular risk calculation in patients with diabetes. Further studies are required to investigate if a correction factor needs to be introduced when these direct assays are used to measure HDL cholesterol in patients with Type 2 diabetes mellitus.
Antibodies↗
The influence of gender on the short and long-term effects of growth hormone replacement on bone metabolism and bone mineral density in hypopituitary adults: a 5-year study.
OBJECTIVES: The objectives of this study were to investigate the effects of GH replacement therapy in hypopituitary adults with growth hormone deficiency (GHD) on activation of bone remodelling during dose titration and on BMD over a median of 58 months of continuous therapy. STUDY DESIGN: Open label study in adult patients with GHD. rhGH was commenced at dose of 0.8 IU subcutaneously daily (0.4 IU if hypertensive or glucose tolerance impaired) with subsequent dose titration based on 2 weekly measurement of serum IGF-I until levels reached the target range (between the median and upper end of the age related reference range). In patients previously commenced on GH using weight based regimens the dose of GH was adjusted during clinical follow-up in order to maintain serum IGF-I in the target range. PATIENTS: Initial effects of GH on bone remodelling during dose titration were studied in 17 patients (8F). Long-term effects of GH were determined in a separate group of 13 GHD adults (6F) over a median period of 58 months (range 44-72). MEASUREMENTS: Osteoblastic activity was estimated by measuring serum bone specific alkaline phosphatase (S-BAP). BMD was determined at both lumbar spine (L2-L4) and femoral neck by dual energy X-ray absorptiometry (DEXA). RESULTS: During dose titration a significant increment in S-BAP was observed by 10 weeks in females but occurred later in males (12-26 weeks). In the long term treatment group there was a significant increment in S-BAP compared to baseline (P = 0.013) after 6 months GH treatment. After long-term GH treatment (median 58 months) S-BAP levels decreased and were no longer statistically significantly different from baseline at the end of the study period. A similar response was observed in male and female patients. There were no significant differences in baseline BMD between male and female patients at either lumbar spine or femoral neck in the long term treatment group. No significant changes were observed in BMD after 6 months GH treatment in either lumbar spine or femoral neck but BMD increased over the remainder of the study at both sites (P = 0.023 and P = 0.03 respectively). When analysed by gender male patients showed a clear positive change in BMD after longer-term replacement in both lumbar spine and femoral neck (P = 0.01 and P = 0.02 respectively) but female patients showed no significant changes. Qualitatively similar results were observed when analysing changes in BMD expressed as Z scores. CONCLUSION: This study demonstrates an earlier onset of GH activation of bone remodelling as reflected by S-BAP in females compared to males and confirms that long-term GH treatment in hypopituitary adults with GH deficiency increases or preserves BMD both at lumbar spine and femoral neck. However male patients seem to derive the greater benefits in BMD from long-term GH replacement; in females BMD appears simply to be stabilized rather than increased. This constitutes a genuine gender difference in susceptibility given that serum IGF-I was in the upper part of the reference range in all subjects.
Adult↗
Are we in danger from an epidemic of Cushing's syndrome? Nature knows its course.
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Adrenocorticotropic Hormone↗
The N363S polymorphism of the glucocorticoid receptor: potential contribution to central obesity in men and lack of association with other risk factors for coronary heart disease and diabetes mellitus.
Considerable evidence suggests that diabetes mellitus and hypertension are influenced by genetic factors. Studies in humans have associated glucocorticoid receptor (GR) polymorphisms with high blood pressure, insulin sensitivity, body mass index, increased visceral fat, and variations in tissue-specific steroid sensitivity. The N363S polymorphism of the GR results in an asparagine to serine amino acid substitution in a modulatory region of the receptor. Phosphorylation of serine residues in this region has been shown to enhance transactivation of GR responsive genes. The aim of this study was to investigate the association between the 363S allele and risk factors for coronary heart disease and diabetes mellitus in a population of European origin living in the northeast of the United KINGDOM: Blood samples from 135 males and 240 females were characterized for 363 allele status. The overall frequency of the 363S allele was 3.0%, 23 heterozygotes (7 males and 16 females) but no 363S homozygotes were identified. The data show a significant association of the 363S allele with increased waist to hip ratio in males but not females. This allele was not associated with blood pressure, body mass index, serum cholesterol, triglycerides, low-density lipoprotein and high-density lipoprotein cholesterol levels, and glucose tolerance status. The results of this study suggest that this GR polymorphism may contribute to central obesity in men. Further studies are required to elucidate the properties of GR(363S) at a molecular level.
Adult↗
Appropriate insulin regimes for type 2 diabetes: a multicenter randomized crossover study.
OBJECTIVE: To directly compare the rate of hypoglycemia and metabolic control achieved on once-daily ultralente insulin administration with twice-daily NPH insulin administration in patients with type 2 diabetes. Patient treatment satisfaction and quality of life were also examined before and during each treatment. RESEARCH DESIGN AND METHODS: A crossover study was performed involving five centers and 79 patients with type 2 diabetes (fasting blood glucose > 8 mmol/l) with a 2-month run-in followed by two 6-month periods of either NPH or ultralente insulin administration. Patients were managed by a specialist nurse using a dosage adjustment protocol. RESULTS: HbA1c was lower with NPH insulin therapy during each of the 6-month periods (9.7 +/- 0.2 vs. 9.1 +/- 0.3 and 9.8 +/- 0.2 vs. 9.0 +/- 0.3 mmol/l; both P < 0.01). The difference was accounted for by higher evening glucose levels with ultralente insulin (fasting 8.2 +/- 0.3 vs. 8.2 +/- 0.3 mmol/l, 6:00 P.M. 11.5 +/- 0.4 vs. 10.6 +/- 0.4 mmol/l). Despite worse control, the total number of hypoglycemic episodes was greater with ultralente insulin (220 vs. 171), and hypoglycemic episodes requiring third-party assistance occurred almost entirely with ultralente (14 vs. 1). Treatment satisfaction scores increased more with NPH insulin compared with ultralente and rose further upon changing to NPH insulin, but fell upon changing to ultralente insulin. These changes were highly significant (P < 0.001). Diabetes quality of life improved on both regimens. CONCLUSIONS: These data clearly demonstrate the lower hypoglycemia rate, better glucose control, and greater treatment satisfaction accompanying therapy for type 2 diabetes with twice daily NPH compared with once daily ultralente insulin.
Blood Glucose↗
Sexual dimorphism in 11 beta hydroxysteroid dehydrogenase activity and its relation to fat distribution and insulin sensitivity; a study in hypopituitary subjects.
OBJECTIVE: Sexual dimorphism of 11 beta hydroxysteroid dehydrogenase activity (11 beta HSD) as measured by the urinary 11-OH/11-oxo cortisol metabolite ratio has been documented in healthy subjects. Since body composition, fat distribution and insulin sensitivity vary between the sexes we have investigated whether these factors may account for the observed difference. Studies were performed in ACTH deficient hypopituitary subjects to eliminate the effect of feedback modulation of cortisol secretion. DESIGN AND PATIENTS: 44 hypopituitary patients, (m:f, 32:12), median age 51 years, median weight 86 kg, on hydrocortisone and other replacement therapy as appropriate were studied. MEASUREMENT: Urine 11-OH/11-oxo cortisol metabolites and serum and urine cortisone (E) and cortisol (F) were measured in relation to total cortisol metabolites and cortisol binding globulin; fat distribution was assessed by Dual Energy X-ray absorptiometry (DXA), and insulin sensitivity by homeostatic model of assessment. RESULTS: Cortisol bioavailability (total urine cortisol metabolites, urine free cortisol and cortisol binding globulin) was similar in both sexes. The 11-OH/11-oxo ratio was lower in females than males (median; 0.99 vs 1.3, P < 0.03) while thyroid status was similar. Females had higher percentage fat (median 47.7 vs 34.9, P < 0.01); total fat (median 39.5 vs 34.9 kg, P < 0.01), android fat (median 9.1 vs 6.6 kg, P < 0.01); gynoid fat (median; 9.9 vs 6.8 kg, P < 0.05) and lower insulin sensitivity (median 15.3 vs 30.6, P < 0.01). In all subjects, the 11-OH/11-oxo ratio was inversely related to body weight (P < 0.01), % fat (P < 0.05), total fat (P < 0.01), android fat (P < 0.01), gynoid fat, (P < 0.01) and directly correlated to insulin sensitivity, P < 0.01. Stepwise regression analysis showed gynoid fat to be the most important factor determining the 11-OH/11-oxo ratio. In 24 subjects (f:m, 8:16) on exogenous sex steroid therapy insulin sensitivity was similar but the sexual dimorphism of the 11-OH/11-oxo ratio remained unchanged (median; 1.0 vs 1.7, P < 0.05). The urine and serum F and E and their ratio (F/E) were similar in these groups. CONCLUSION: These data confirm the presence of sexual dimorphism in 11 beta-hydroxysteroid dehydrogenase activity in hypopituitary patients as described in normal individuals. This is the first in vivo evidence that this dimorphism is related to body composition. Our findings suggest that sexual dimorphism may be determined by the activity of type 1 and not type 2 11 beta-hydroxysteroid dehydrogenase.
11-beta-Hydroxysteroid Dehydrogenases↗
The effect of growth hormone replacement therapy on cortisol-cortisone interconversion in hypopituitary adults: evidence for growth hormone modulation of extrarenal 11 beta-hydroxysteroid dehydrogenase activity.
OBJECTIVE: Growth hormone (GH) replacement therapy in hypopituitary adults has been associated with a decreased urinary ratio of 11-hydroxy/11-oxo-cortisol metabolites (CoM). This could result from GH regulation of the activity of hepatic or renal 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD1 and 2), the enzymes responsible for cortisol-cortisone interconversion, or alternatively it might reflect decreased cortisol availability. To elucidate this, we examined the effect of GH on urinary cortisol, cortisone and cortisol metabolites in hypopituitary adults at increasing doses of hydrocortisone replacement. DESIGN: Patients received increasing twice daily doses of hydrocortisone (HC) (10/10, 20/10, 40/20 mg) each week, before and during 2 months of GH replacement (0.25 U/kg/week). PATIENTS: Seven hypopituitary adults (three men and four women, age range 47-64 years) with combined GH and ACTH deficiency. Three additional patients with GH deficiency, but intact ACTH reserve, were also studied. MEASUREMENTS: Urine steroid metabolite profiles were measured in 24-hour urine collections by gas chromatography after each week of treatment. Urinary free cortisol and free cortisone were measured by radioimmunoassay as a measure of renal 11 beta-HSD-2 activity. RESULTS: Total urinary CoM increased with rising doses of HC, but at each particular HC dose, were unchanged after GH (before versus after GH, median (range): 9.67 (7.86-12.59) versus 9.93 (8.31-14.08); 15.87 (12.37-31.39) versus 17.07 (12.64-23.81); 26.68 (19.07-42.14) versus 26.77 (8.01-37.62) mg/24 hours). The urine ratio 11-hydroxy/11-oxo-CoM decreased significantly with GH treatment, at each HC dose schedule (1.22 (1.02-1.96) versus 0.92 (0.83-1.63) P = 0.018; 1.53 (1.30-2.23) versus 1.23 (0.93-1.46) P = 0.018; 1.87 (1.45-2.70) versus 1.56 (1.22-1.79) P = 0.018). The urinary ratio tetrahydrocortisols/tetrahydrocortisone, an alternative index of 11 beta-HSD activity, also fell with GH therapy at each HC dose (P = 0.049; P = 0.018; P = 0.043). In contrast, the urinary 20-hydroxy/20-oxo-CoM ratio exhibited a small increase with GH, suggesting that the changes observed above were not simply due to changes in redox status. The patients with GH deficiency, but intact ACTH reserve, demonstrated changes in urine steroid profiles similar to the group receiving hydrocortisone replacement. Urinary free cortisone and urinary free cortisol/free cortisone ratios did not change with GH therapy, but the serum cortisol/ cortisone ratio fell significantly with GH therapy at each hydrocortisone dose. CONCLUSIONS: GH therapy decreases the urinary ratios 11-hydroxy/11-oxo-cortisol metabolites and tetrahydrocortisols/tetrahydrocortisone, but not urinary free cortisone or the urinary free cortisol/free cortisone ratio. This effect is not secondary to reduced cortisol availability. These findings provide further evidence for direct or indirect modulation of cortisol metabolism by growth hormone and suggest that this occurs at hepatic or an alternative site of 11 beta-hydroxysteroid dehydrogenase-1 activity.
11-beta-Hydroxysteroid Dehydrogenases↗
Genetic contribution of polymorphism of the GLUT1 and GLUT4 genes to the susceptibility to type 2 (non-insulin-dependent) diabetes mellitus in different populations.
Polymorphic variation of genes encoding the glucose transporters glycoproteins (GLUT) may contribute to the genetic susceptibility to type 2 (non-insulin-dependent) diabetes. In this study we evaluated the allele and genotype frequencies of GLUT1 and GLUT4 restriction fragment length polymorphism (RFLP), revealed by digestion with XbaI for GLUT1 and KpnI for GLUT4, in Caucasian, Chinese, Japanese, Asian Indian and American black populations. No differences of the KpnI GLUT 4 RFLP were found between control and diabetic subjects in any ethnic group or when all data are combined. In contrast, positive results were found for the XbaI RFLP: (1) most ethnic groups showed an association of allele 1 with type 2 diabetes, and this association was maintained when all groups were analysed together; (2) after stratifying for sex and obesity, this association was significant only for overweight/obese women. This joint analysis suggests that GLUT1 polymorphism may contribute to susceptibility to type 2 diabetes in some populations, and especially in overweight/obese women.
Adult↗
The effect of low dose recombinant human growth hormone replacement on regional fat distribution, insulin sensitivity, and cardiovascular risk factors in hypopituitary adults.
GH deficiency is associated with increased cardiovascular morbidity, which may be determined by alterations in vascular risk factors. We report the effect of partially treated hypopituitarism and subsequent GH replacement (mean dose, 0.2 IU/kg.week) on putative cardiovascular risk factors in 22 nondiabetic hypopituitary subjects in a 6-month, double blind, controlled study (active/placebo ratio, 11:11). All patients were subsequently treated with GH for a further 6 months. Total fat, percent body fat, and central fat were measured by dual energy x-ray absorptiometry. The hypopituitary patients had increased percent fat (P = 0.03) and central fat (P < 0.01) compared with body mass index-matched controls. Before GH treatment, fasting (total) and specific insulin positively correlated with body mass index (P = 0.02 and P < 0.001, respectively), waist/hip ratio (P = 0.05 and P = 0.01), and central fat (P = 0.03 and P = 0.003). Specific insulin and insulin sensitivity (IS), calculated by homeostatic model of assessment, were related to total fat (P < 0.001 and P = 0.02). GH treatment for 6 months led to a reduction in total fat (P < 0.02), percent fat (P = 0.002), central fat (P = 0.012), waist/hip ratio (P < 0.05), total cholesterol (P = 0.03), and apolipoprotein-B (P = 00001), as well as a decrease in the IS from 36.9% (range, 12-100%) to 25% (range, 2.5-55%; P = 0.0002). This was paralleled by a rise in fasting (total) and specific insulin (P = 0.016 and P = 0.002). The degree of correlation among indices of IS, body composition, and fat distribution increased after GH treatment. Fasting plasma glucose rose significantly, but was within the reference range. During 12 months of GH therapy, a significant increase in serum lipoprotein-(a) was observed (P < 0.05). Although GH has beneficial effects on central adiposity and lipid fractions, it is also associated with a decrease in IS; these effects may vary between individuals.
Adipose Tissue↗
The effect of growth hormone replacement on cortisol metabolism and glucocorticoid sensitivity in hypopituitary adults.
OBJECTIVE: Growth hormone (GH) replacement therapy in hypopituitary adults is associated with sodium and water retention. The underlying mechanisms are incompletely understood and a possible contribution of altered cortisol metabolism or action has not been evaluated. We have investigated the effect of GH replacement therapy on cortisol metabolism, cortisol binding globulin and in-vitro glucocorticoid sensitivity in a group of adult hypopituitary patients. DESIGN AND PATIENTS: We studied 19 adult hypopituitary patients (18 adult onset, M:F, 6:13), who were receiving conventional hydrocortisone (16 patients), thyroxine (14 patients), triiodothyronine (1 patient), sex steroid (9 patients), human chorionic gonadotrophin (1 patient) or desmopressin (6 patients) replacement during a 6-month, double blind controlled trial of GH therapy (active:placebo, 8:11) followed by a 6-month open phase of GH (mean dose: 0.2 IU/kg/week, range 0.051-0.27) and after a 6-week washout phase following discontinuation of GH therapy. MEASUREMENTS: Twenty-four-hour urine free cortisol, cortisol metabolites (CoM), ratio 11-hydroxy/11-oxo CoM (F/E) and ratio 5 alpha/beta tetrahydrocortisol were measured at 6 months, 12 months and after the 6 week washout phase. Serum cortisol binding globulin was measured basally, at 6 months, 12 months and after washout. Glucocorticoid sensitivity was determined in lymphocyte preparations from 8 patients, during GH therapy and after washout, using an in-vitro technique dependent on dexamethasone suppression of phytohaemagglutinin-stimulated thymidine incorporation into DNA. Plasma renin activity and aldosterone were measured after 6-12 months GH therapy and after washout. RESULTS: After 6 months of GH, in patients on hydrocortisone (n = 9), there were significant decreases in CoM (mean decrement 21%, P < 0.01), F/E (mean decreased from 1.27 to 1.0, P = 0.04; reference range 0.33-1.29) and 5 alpha/5 beta tetrahydrocortisol (mean decreased from 0.67 to 0.48, P = 0.01) and a subsequent increase after washout. Patients not on hydrocortisone (n = 2) demonstrated a normal basal F/E falling by 25% on GH therapy but no change in CoM. During 12 months of GH therapy, patients on hydrocortisone (n = 7) demonstrated a further trend to decrement in CoM (P = 0.09) which reversed after washout (P = 0.04). Urine free cortisol tended to fall during GH therapy and increased significantly following washout after 12 months treatment (P < 0.02). Serum cortisol binding globulin decreased by 20% (P < 0.05) during 12 months GH treatment but remained within the reference range. In-vitro studies demonstrated a trend to reduced glucocorticoid sensitivity on GH therapy; the maximum inhibition of phytohaemagglutinin by dexamethasone tended to be less on GH therapy (P = 0.052) and was also lower than in 29 normal volunteers (P < 0.05). There were no significant changes in plasma renin but there was a small increment in aldosterone in recumbent patients (P = 0.04) during the open phase of GH therapy in the placebo arm. CONCLUSIONS: GH therapy in hypopituitary adults is associated with an apparent reduction in availability of administered hydrocortisone as measured by urine cortisol metabolites and urine free cortisol. This effect is unlikely to be clinically significant except possibly in ACTH deficient subjects on suboptimal hydrocortisone replacement. The changes in F/E suggest that GH may directly or indirectly modulate the activity of 11 beta-hydroxysteroid dehydrogenase. The apparent decrease in glucocorticoid sensitivity during GH therapy, demonstrated in vitro, merits further investigation.
Adult↗
Hyperactivity of the hypothalamo-pituitary-adrenal axis in obesity: a study of ACTH, AVP, beta-lipotrophin and cortisol responses to insulin-induced hypoglycaemia.
OBJECTIVE: The purpose of this study was to determine whether alterations in the hypothalamo-pituitary-adrenal axis and arginine vasopressin secretion, which have been associated with animal obesity, also occur in man. DESIGN: Cross-sectional analysis of extremely obese women and normal weight controls. PATIENTS: Thirty-three obese premenopausal, non-diabetic women (mean age 31 years, mean body mass index (BMI) 41), and 15 normal weight controls (mean age 24 years, mean BMI 22). MEASUREMENTS AND RESULTS: Arginine vasopressin (AVP), ACTH, beta-lipotrophin and cortisol responses to insulin-induced hypoglycaemia (0.2 units Actrapid/kg body weight for obese; 0.15 unit/kg for controls) were measured. The obese women were further characterized by anthropometric measurements (weight, body mass index, fat distribution) and indices of insulin secretion/resistance: fasting insulin, insulin secretion during 75-g oral glucose tolerance test area under curve, insulin-stimulated glucose disposal and an index of insulin resistance. No significant differences were found in the basal levels of ACTH, AVP, beta-lipotrophin or cortisol. An augmented peak beta-LPH (n = 16, P < 0.02, the difference of the mean 3.65, 95% confidence interval 1.33-10) and ACTH (n = 16, P = 0.05, the difference of the mean 2.12, 95% CI 1.0-4.5) response were found in obese as compared with normal weight controls. Both ACTH and AVP areas under the curve were similar in both groups studied. There was additionally a direct positive association between the integrated ACTH response (area under the curve) and the weight of the obese subjects (P < 0.05, r2 = 0.265). The cortisol response was negatively correlated with insulin-stimulated glucose disposal (P < 0.01, r2 = 0.23), but not with other indices of insulin secretion/resistance (fasting insulin, oral glucose tolerance test area under the curve, index of insulin resistance) or fat distribution. Comparable responses to hypoglycaemia were seen for AVP and cortisol. There was no correlation between the ACTH, AVP or cortisol responses. CONCLUSION: Obesity is associated with increased activity of the hypothalamo-pituitary-adrenal axis as supported by augmented ACTH and beta-lipotrophin secretion in response to insulin-induced hypoglycaemia and the positive association between the ACTH response and the body weight of obese women studied.
Adrenocorticotropic Hormone↗
Central obesity and hyperinsulinaemia in women are associated with polymorphism in the 5' flanking region of the human insulin gene.
Obesity is a multifactorial disease with a marked genetic component. The situation is further complicated by the heterogeneity of obesity demonstrated by the topographical distribution of body fat, e.g. upper body (central) and lower body (gluteal) obesity. Furthermore, the distribution of fat shows a stronger heritable tendency compared with total body fat. Central obesity is characterized by hyperinsulinaemia and insulin resistance, a feature in common with non-insulin dependent diabetes mellitus, hypertension and atherosclerosis. In order to study the molecular genetics of central obesity we have examined 56 severely obese (mean body mass index 40), unrelated British Caucasoid young non-diabetic women for associations of restriction fragment length polymorphism of candidate genes with anthropometric measurements and indices of insulin secretion and resistance. The candidate genes examined were insulin receptor, insulin sensitive glucose transporter and insulin. An association of the class 3 allele of the hypervariable region in the 5' flanking region of the insulin gene was found with upper segment obesity (P = 0.005). Furthermore, the class 3 allele was also associated with fasting hyperinsulinaemia (P = 0.01), stimulated insulin secretion (P = 0.01) and insulin resistance as calculated from the homeostatic model of assessment (HOMA; P = 0.008). No such associations were found with the other candidate genes studied. This data suggests that polymorphisms in the 5' flanking region of the insulin gene may affect expression of the gene and thereby modulate insulin production in severely obese female subjects.
Adult↗