GH replacement in 1034 growth hormone deficient hypopituitary adults: demographic and clinical characteristics, dosing and safety

Optimizing gh therapy in adults and children

Until the advent of modern neuroradiological imaging techniques in 1989, a diagnosis of GH deficiency in adults carried little significance other than as a marker of hypothalamo-pituitary disease. The relatively recent recognition of a characteristic clinical syndrome associated with failure of spontaneous GH secretion and the potential reversal of many of its features with recombinant human GH has prompted a closer examination of the physiological role of GH after linear growth is complete. The safe clinical practice of GH replacement demands a method of judging overall GH status, but there is no biological marker in adults that is the equivalent of linear growth in a child by which to judge the efficacy of GH replacement. Assessment of optimal GH replacement is made difficult by the apparent diverse actions of GH in health, concern about the avoidance of iatrogenic acromegaly, and the growing realization that an individual's risk of developing certain cancers may, at least in part, be influenced by cumulative exposure to the chief mediator of GH action, IGF-I. As in all areas of clinical practice, strategies and protocols vary between centers, but most physicians experienced in the management of pituitary disease agree that GH is most appropriately begun at low doses, building up slowly to the final maintenance dose. This, in turn, is best determined by a combination of clinical response and measurement of serum IGF-I, avoiding supraphysiological levels of this GH-dependent peptide. Numerous studies have helped define the optimum management of GH replacement during childhood. The recent requirement to measure and monitor GH status in adult life has called into question the appropriateness of simplistic weight- and surface area-based dosing regimens for the management of GH deficiency in childhood, with reliance on linear growth as the sole marker of GH action. It is clear that the monitoring of parameters other than linear growth to help refine GH therapy should now be incorporated into childhood GH treatment protocols. Further research will be required to define the optimal management of the transition from pediatric to adult GH replacement; this transition will only be possible once the benefits of GH in mature adults are defined and accepted by pediatric and adult endocrinologists alike.

Growth hormone therapy in adults

The importance of growth hormone (GH) deficiency in adults became evident 10 to 15 years ago, when the first clinical studies on GH replacement therapy in adults were published. Since then, a number of studies have been reported showing that GH replacement therapy can improve this condition. Adult GH deficiency (GHD) is now recognized as a specific clinical syndrome and the first reports of long-term use of GH (up to 10 years) are now being published. The aim of this paper was to review the accumulated data on the various clinical aspects of adult GHD.

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.

The influence of growth hormone deficiency, growth hormone replacement therapy, and other aspects of hypopituitarism on fracture rate and bone mineral density

To assess the influence of factors affecting fracture risk and bone density in adult hypopituitary patients with growth hormone deficiency (GHD), data from a large-scale pharmacoepidemiological survey (the Pharmacia & Upjohn International Metabolic Database [KIMS]) were analyzed and compared with data from a control population (the European Vertebral Osteoporosis Study [EVOS]). The KIMS group consisted of 2084 patients (1112 men and 972 women) with various types of pituitary disease and EVOS consisted of 1176 individuals (581 men and 595 women). Fracture and bone mineral density (BMD) data were available from 2024 patients from the KIMS group and 392 patients from EVOS. The prevalence of fractures in patients with hypopituitarism was 2.66 times that in the non-GH-deficient EVOS population. Adult-onset hypopituitarism with GHD was associated with a higher fracture risk than childhood-onset disease, and patients with isolated GHD had a similar prevalence of fractures to those with multiple pituitary hormone deficiencies. Hormonal replacement therapy with L-thyroxine, glucocorticoids, and sex steroids did not affect the risk of fracture in KIMS patients. In addition, fracture rates in KIMS were independent of body mass index (BMI) and the country of origin. However, smoking was associated with a higher fracture rate in this group. In summary, this is the first large-scale analysis to support the hypothesis of an increased fracture risk in adult patients with hypopituitarism and GHD. This increased risk appears to be attributable to GHD alone, rather than to other pituitary hormone deficiencies or to their replacement therapy.

Hypogonadism in patients with acromegaly: data from the multi-centre acromegaly registry pilot study

OBJECTIVE

Because acromegaly is an uncommon disorder, epidemiological data regarding the demographics of the disease such as the prevalence of hypogonadism have been limited. In order to derive clinical and epidemiological information, including underlying hormonal factors, regarding hypogonadism in patients with acromegaly, we performed a pilot study designed to develop a multi-centre acromegaly patient registry.

DESIGN AND MEASUREMENTS

Medical records of patients with acromegaly seen between 1976 and 1996 at three Institutions were reviewed, and data were entered into a database using a secure internet website. Hypogonadism was defined as amenorrhoea in women and testosterone deficiency in men. Subanalysis was performed in patients with microadenomas and women less than 50 years of age, to include women of reproductive age.

RESULTS

Information was available on 363 patients, of whom 54% were women. The mean age at diagnosis was 41 +/- 13 years. In subjects less than 50 years of age, hypogonadism was present in 59%. Hyperprolactinaemia was present in 45% and 21% of hypogonadal and eugonadal patients of reproductive age, respectively (P = 0.0003). GH levels were higher in patients with hypogonadism (P = 0.03). In patients < 50 years of age with microadenomas, hypogonadism was present in nine of the 22 (41%) patients, including 55% of the women and 27% of the men (P = ns). Hyperprolactinaemia was present in three of the 10 and four of the 14 of microadenoma patients with hypogonadism and eugonadism, respectively.

CONCLUSION

We developed a web-based acromegaly patient registry and used it to show that hypogonadism is a frequent consequence of acromegaly, even in patients with microadenomas, who are not at risk from hypopituitarism due to local mass effects. We also demonstrated that prolactin and GH hypersecretion contribute to the pathogenesis of hypogonadism in acromegaly, and that hypogonadism may occur in microadenoma patients even in the absence of hyperprolactinaemia.

Does the GH-IGF axis play a role in cancer pathogenesis?

Recent case-controlled studies have found increases in the serum levels of insulin-like growth factor-I (IGF-I) in subjects who had, or who eventually developed, prostate or premenopausal breast cancers. Since growth hormone (GH) increases IGF-I levels, concern has been raised regarding its potential role as a cancer initiation factor. The epidemiological studies, which indicate an association between serum IGF-I levels and cancer risk, have not established causality. In fact, several alternative explanations for the elevated serum IGF-I levels in cancer patients may be proposed based on human and animal models. First, an effect of IGF-I causing symptomatic benign tissue hyperplasia may result in an ascertainment bias leading to an initiation of procedures resulting in the diagnosis of asymptomatic cancers. Second, elevated serum IGF-I in cancer patients may originate within the tumor (as suggested by some animal studies). Thirdly, serum IGF-I may actually be a surrogate marker of tissue IGF-I levels or of nutritional factors, which are not under GH control and may be involved in cancer initiation. The role of GH in cancer initiation is further negated by the fact that in acromegaly, the incidence of cancer, other than possibly colonic neoplasia does not appear to be significantly increased. Furthermore, GH transgenic mice, with high IGF-I levels, do not develop breast, prostate, or colonic malignancies. It is known that IGFBP-3 can inhibit IGF action on cancer cells in vitro and also can induce apoptosis via an IGF-independent mechanism. Importantly, in addition to increasing IGF-I levels, GH also increases the serum levels of IGFBP-3 and serum IGFBP-3 levels have been shown to be negatively correlated with the risk of cancer in the above mentioned epidemiological studies and in a similar study on colon cancer. These studies suggest that cancer risk is increased in individuals in whom both high IGF-I levels and low IGFBP-3 levels are present. In subjects treated with GH, IGF-I and IGFBP-3 levels both rise together and are not within the elevated cancer-risk range, based on published studies. Long-term studies are needed to assess the potential risks, including the long-term cancer risk associated with GH therapy. These should take into account several factors, including the duration of exposure, the risk magnitude associated with the degree of serum IGF-I elevation, and the adjusted risk based on a concomitant increase in IGFBP-3 levels. Since GH treated patients often have sub-normal IGF-I serum levels, which normalize on therapy, one might predict that their cancer risk on GH therapy should not increase above the normal population. Until further research in the area dictates otherwise, on-going cancer surveillance and routine monitoring of serum IGF-I and IGFBP-3 levels in GH-recipients should be the standard of care. At present, the data that are available do not warrant a change in our current management of approved indications for GH therapy.

Elderly people with hypothalamic-pituitary disease and growth hormone deficiency: lipid profiles, body composition and quality of life compared with control subjects

OBJECTIVE

In healthy adults the secretion of growth hormone (GH) and insulin-like growth factor 1 (IGF-1) declines with ageing and body composition alters, particularly with an increase in total body fat. In elderly people, hypothalamic-pituitary disease can cause GH deficiency (GHD), compared with age matched controls. This study aimed to clarify whether GHD in the elderly is associated with differences in body composition, circulating lipid levels and quality of life (QOL) compared with control subjects.

SUBJECTS

Twenty-seven elderly patients (14 males, mean age 71 years, range 65-83) with hypothalamic-pituitary disorders (23 pituitary tumours) and GHD (mean (SD) peak stimulated GH response 1.6 mIU/l (1.03) range 0.6-5) were studied. Twenty-five patients had been treated surgically (six cranial surgery, 19 transsphenoidal) and eight patients had received external cranial irradiation. Twenty-seven control subjects (14 males, mean age 72 years, range 65-86) were also studied.

METHODS

Weight, body mass index (BMI), total fat mass (FM, bioelectrical impedance), waist to hip ratio (WHR), serum IGF-1, fasting blood glucose and lipid profile were measured. QOL was assessed in both groups using five interviewer administered self-rating questionnaires: The Nottingham Health Profile, Short-Form 36, Hospital Anxiety and Depression Scale, Mental Fatigue Questionnaire and Life Fulfilment Scale. The GHD group also completed the Disease Impact Scale.

RESULTS

The data (mean (SD)) from males and females were analyzed separately. The male patients had a higher BMI than controls, 28.9(4.5) vs. 25.2(2.3) kg/m2 (P = 0.01) but the BMI in the female patients and controls was similar. In the female patients compared with the controls, FM was higher 39. 4(6) vs. 33.1(8.3) % (P = 0.02), WHR was also higher 0.9(0.08) vs. 0. 83(0.09) (P = 0.03) and serum IGF-1 levels were lower 10.8(6.4) vs. 18.2(6.5) nmol/l (P = 0.01). However, in the male patients, FM, WHR and IGF-1 levels were similar to the controls. Fasting blood glucose was similar in both male and female patients and the controls. Two female patients and one male control subject were taking lipid-lowering agents and were therefore excluded from the analysis of lipid profiles. Total cholesterol, triglyceride, LDL cholesterol, HDL cholesterol and total cholesterol/HDL cholesterol ratio were not significantly different for both male and female patients compared with the controls. The 27 patients with GHD reported significantly less energy (P < 0.05), mobility (P < 0.05) and personal life fulfillment (P < 0.01) than the 27 controls. There were significantly more problems with emotional reaction (P < 0.01), social isolation (P < 0.05) and mental fatigue (P < 0.05). Additionally the GHD group reported more impairment in areas of social functioning (P < 0.05), general health (P < 0.05) and mental health (P < 0.05). The GHD group reported a modest degree of disease impact (mean score of 14.1). There were no significant differences in the domains of material life fulfillment, pain, sleep, physical functioning, vitality, anxiety, depression, self-esteem or role physical functioning compared with the controls.

CONCLUSION

Compared with control subjects, the elderly female patients with hypothalamic-pituitary disease and GHD had a significantly higher total fat mass, with the WHR indicating a more central fat distribution and lower female serum IGF-1 levels. In contrast, elderly male patients had similar total fat mass, WHR and IGF-1 levels compared to the controls. There were no significant differences in the lipid profiles between male or female patients compared to controls. However, many of the male patients were receiving androgen replacement which might have influenced these results. Low HDL cholesterol concentrations are probably a better predictor of future cardiovascular disease than raised LDL cholesterol levels in the elderly population and these were similar in patients and controls for both

Should we start and continue growth hormone (GH) replacement therapy in adults with GH deficiency?

During the last decade, growth hormone deficiency (GHD) in adults has been described as a clinical syndrome. Central features of this entity include increased fat mass, reduced muscle and bone mass, as well as impaired exercise capacity and quality of life. GH replacement therapy has been initiated on a wide scale, but patients do not profit equally from this expensive therapy. The decision to start and continue GH replacement should be made individually for each patient. An eligible patient should have a clear diagnosis of GHD. In addition, GH replacement therapy should be efficacious. Especially, the unique and valuable effects of GH replacement on exercise performance and quality of life are strong arguments in favour of continuation of therapy. In osteopenic patients, GH replacement increases bone mass. Also, GH induces improvements in the cardiovascular risk profile. However, it has not yet been proved whether GH replacement reduces the incidence of bone fractures and cardiovascular mortality and improves life expectancy. Thus far, long-term physiological GH replacement does not appear to be complicated by adverse effects. Therefore, available evidence warrants continuation of long-term GH replacement therapy in patients with a clear-cut diagnosis of GHD who demonstrate beneficial effects of this therapy, especially with regard to exercise performance and quality of life.

Sustained reduction in circulating cholesterol in adult hypopituitary patients given low dose titrated growth hormone replacement therapy: a two year study

OBJECTIVE

To study the effects of short (6 months) and longer-term (up to 24 months) growth hormone (GH) replacement therapy using a dose titration regimen, on lipid and glucose metabolism in GH-deficient, hypopituitary adults.

DESIGN

On-going open study of GH treatment up to 24 months. Measurements were performed at baseline and at 6, 12, 18 months and 2 years during therapy (data shown at 6 months and 2 years only). Using a dose titration regimen the median GH dose used to achieve and maintain IGF-I levels above the median, but below the upper limit of the age-related reference range (median IGF-I 202.5 microg/l, range 76-397 microg/l), was 1.2 IU daily (range 0.4-3 IU) [0.8 IU/day, males; 1.6 IU/day, females].

PATIENTS

Ninety GH-deficient hypopituitary adults (54 female, median age 48 years, range 19-79 years) entered the study and 24 (14 female, median age 45 years, range 32-79 years) have concluded the 2 year period of assessment.

MEASUREMENTS

Body mass index (BMI), waist and hip circumference ratio (WHR), fasting lipids, glucose and glycated haemoglobin (HbA1c) levels were measured at 6 month intervals during GH therapy.

RESULTS

Using the dose titration regimen, compared to pretreatment values, total and low density lipoprotein (LDL)-cholesterol levels were significantly lower at 6 months (mean +/- SEM, 5.61+/-0.1 vs. 5.25+/-0.1, and 3.85+/-0.19 vs. 3.43+/-0.26, respectively, P<0.05), and were maintained throughout the study. Male patients had significantly lower pretreatment total and LDL cholesterol levels than females (mean +/- SEM, 5.33+/-0.16 mmol/l vs. 5.7+/-0.12 mmol/l and 3.8+/-0.23 mmol/l vs. 3.92+/-0.29 mmol/l, respectively, P< 0.05). A decrease in total cholesterol was confined to patients with pretreatment total cholesterol levels above 5.8 mmol/l; patients with the highest pretreatment cholesterol levels (> 6.4 mmol/l) obtained the greatest cholesterol reduction (mean +/- SEM, 7.13 +/- 0.14 mmol/l vs. 5.76+/-0.31 mmol/l, P<0.05). A cholesterol-lowering effect of GH therapy was evident in patients who had elevated pre-GH total cholesterol levels even if they were already receiving and continuing lipid lowering medication (mean +/- SEM, 5.62+/-0.22 vs. 5.03+/-0.285, P<0.05). A modest increment in high density lipoprotein (HDL)-cholesterol was evident at 18 months but there was no significant change in triglycerides at any time point. Fasting plasma glucose increased significantly at 6 months but remained within the reference range. Glycated haemoglobin increased significantly at 6 months and was maintained throughout the study; one patient developed frank diabetes mellitus while receiving treatment. There was a weak but significant correlation between the increment in glycated haemoglobin and pretreatment BMI (r = + 0.215, P<0.05).

CONCLUSION

The effect of GH on lowering total and low density lipoprotein-cholesterol is more prominent in patients with higher pretreatment cholesterol levels and is evident even in patients receiving other lipid-lowering medication. A modest increment in mean fasting glucose (within the reference range) and mean glycated haemoglobin persisted throughout the study. One patient developed diabetes mellitus. A GH replacement regimen using low dose and careful titration to avoid elevated IGF-I levels and adverse effects is associated with sustained beneficial effects on circulating lipids.

Growth hormone deficiency and replacement in elderly hypopituitary adults. KIMS Study Group and the KIMS International Board. Pharmacia and Upjohn International Metabolic Database

OBJECTIVE

Although elderly hypopituitary adults demonstrate an increase in total and central fat compared with age-matched controls and are distinguishable from control subjects in terms of growth hormone (GH) responsiveness on dynamic testing, there are few data available on response to GH replacement. The objective of this study was to compare the baseline characteristics and longitudinal response to GH replacement in patients aged > 65 years with that observed in younger patients enrolled in KIMS (Pharmacia and Upjohn International Metabolic Database). KIMS is a physician-managed, open, long-term surveillance study of adult GH-deficient patients receiving GH replacement. Patients were entered and data provided by interested physicians.

PATIENTS

Baseline characteristics were studied in 109 patients (66 males) aged > 65 years commencing GH replacement at time of entry into KIMS and the effects of GH replacement on blood pressure, lipids and quality of life in 64 patients who had completed at least 6 months of GH replacement. Data were compared with baseline data on 863 patients aged < 65 years with adult onset GH deficiency, who had not received GH for at least 6 months prior to entry into KIMS, 220 of whom went on to complete > 6 months GH therapy in KIMS.

RESULTS

Blood pressure, cholesterol and LDL cholesterol were positively correlated with age, particularly in females, and older patients had a predictably higher prevalence of diabetes mellitus and history of hypertension. The frequency of previous fractures was increased in females but not in males aged > 65 years. Body mass index, waist/hip ratio and quality of life (AGHDA score) was similar in both groups prior to commencement of GH therapy. GH replacement doses were similar in younger and older patients and the percentage of patients with serum IGF-I of > 2SD above the age-related normal mean was not significantly different between the groups (< 65 years, 20%; > 65 years, 11%). After 6 months of GH replacement significant improvements were evident in waist circumference, waist/hip ratio, diastolic blood pressure, total and LDL cholesterol and AGHDA score in patients aged < 65 years. Similar significant reductions in total and LDL cholesterol were evident in patients > 65 years. In addition, male patients aged > 65 years demonstrated significant reductions in diastolic blood pressure and AGHDA score but no change in waist circumference whereas females aged > 65 years demonstrated a trend to reduction in waist circumference and AGHDA score.

CONCLUSIONS

These data, derived from the largest series of GH-treated hypopituitary patients published to date, confirm similar baseline characteristics and positive benefit from GH replacement in older compared with younger hypopituitary patients particularly in relation to quality of life.

Pre-treatment IGF-I level is the major determinant of GH dosage in adult GH deficiency

OBJECTIVE

Severe GH deficiency in adults is a definite clinical entity, the effects of which can be reversed by administration of subcutaneous recombinant GH. The ideal dosing regimen and determinants of the maintenance dose have, however, yet to be elucidated.

PATIENTS

In an open study of GH replacement we treated 65 GH-deficient adults of mixed adult- and childhood-onset, of mean age 35.5 (range 17-72) years, and comprising 38 females and 27 males, using an individualized low-dose titration regimen aimed at normalization of the serum IGF-I and induction of clinical improvement.

RESULTS

Before initiation of GH therapy, median IGF-I SD was significantly lower in female than male patients (- 3.3 vs. - 1.9, P = 0.007) and in childhood-onset compared with adult-onset patients (- 3.9 vs. - 2.0, P < 0.001). Once maintenance dosage had been achieved, the median GH requirement was significantly greater in female than male patients (1.6 vs. 0.8 IU/day, P = 0.013) and childhood-onset compared with adult-onset patients (1.6 vs. 0.8 IU/day, P = 0.019). The median maintenance GH dose for the cohort overall was 1.2 (range 0.4-2.4) IU/day. By univariate analysis a significant negative correlation was observed between the maintenance GH dose and baseline IGF-I SD (r = - 0.63, P < 0.001). No significant correlation was demonstrated between maintenance GH dose and either age or weight. Multiple linear regression analysis using age, gender, weight, time of onset of GH deficiency, peak GH to the insulin tolerance test (ITT) and baseline IGF-I SD as independent variables demonstrated baseline IGF-I SD to account for 51% of the variation in GH dose required to normalize the IGF-I SD (P < 0.001). Those patients with the lower IGF-I SD at initiation of GH therapy required the greater GH dose. None of the other variables studied significantly influenced the maintenance dose.

CONCLUSION

We have demonstrated that the GH dose required in an individual is dependent on the serum IGF-I SD before commencement of replacement. In contrast, the severity of GH deficiency as judged by the peak GH response to an ITT was unrelated to the maintenance GH requirement. The effect of age, gender and age at onset of GH deficiency on the final GH dose are accounted for by the lower pretreatment IGF-I SD in young, female and childhood-onset patients relative to older, male and adult-onset patients, respectively.

The psychological consequences and quality of life in adults with growth hormone deficiency

It is now recognized that adults with pituitary disease and growth hormone (GH) deficiency have impaired physical and psychological functioning, including decreased quality of life. Research on quality of life continues to develop with reference to this patient group. In particular, disease-specific measures of quality of life have been developed, and data on long-term follow-up are now becoming available. Although the majority of studies investigating the effects of GH replacement show that quality of life improves with treatment, the results are not consistent. The relationship between quality of life and depressed mood in GH-deficient adults is complex and needs further study.