Impact of the primary aetiology upon the clinical outcome of adults with childhood-onset GH deficiency

Dyslipidaemia and growth hormone deficiency - A comprehensive review

Growth hormone deficiency (GHD) is a common complication of several pituitary and hypothalamic disorders and dependent on the onset of disease. It may have severe clinical implications ranging from growth retardation in childhood-onset, to impaired lipid metabolism and increased cardiovascular risk and mortality in adults. GH effectively modulates lipid metabolism at multiple levels and GHD has been associated with an atherogenic lipid profile, that can be reversed by GH replacement therapy. Despite increasing knowledge on the effects of GH on several key enzymes regulating lipid metabolism and recent breakthroughs in the development and wider availability of recombinant GH preparations, several questions remain regarding the replacement therapy in adults with GHD. This review aims to comprehensively summarize the current knowledge on (i) lipid profile abnormalities in individuals with GHD, (ii) proposed mechanisms of action of GH on lipid and lipoprotein metabolism, and (iii) clinical implications of GH replacement therapy in individuals diagnosed with GHD.

Growth hormone deficiency in adults with hypopituitarism-What are the risks and can they be eliminated by therapy?

Growth hormone (GH) deficiency develops early in patients with hypothalamic-pituitary disorders and is therefore common among these patients. GH deficiency in adults is associated with increased morbidity, increased body fat mass, abdominal obesity, dyslipidaemia, reduced exercise capacity, impaired cardiac function as well as reduced self-reported well-being and impaired quality of life. Since recombinant human GH became available as replacement therapy more than 25 years ago, randomised controlled trials and long-term studies, together with meta-analyses, have shown improved outcomes in adult patients with hypopituitarism receiving GH. Many of the features associated with GH deficiency in adults improve, or even normalize, and the safety profile is reassuring. The increased interest in GH deficiency in adults with hypothalamic-pituitary disorders has also contributed to the identification of other factors of importance for an outcome such as the replacement of other pituitary hormone deficiencies, and the management of the underlying hypothalamic-pituitary disease, most commonly a pituitary tumour. In this narrative review, we summarize the burden of GH deficiency in adults with hypopituitarism, the impact of GH replacement on the outcome, as well as safety. Based on currently available data, GH replacement should be considered routine management of adults with hypopituitarism.

Mapping the journey of transition: a single-center study of 170 childhood-onset GH deficiency patients

OBJECTIVE

To analyze metabolic parameters, body composition (BC), and bone mineral density (BMD) in childhood-onset GH deficiency (COGHD) patients during the transition period (TP).

DESIGN

Single- center, retrospective study was performed on 170 consecutive COGHD patients (age 19.2 ± 2.0 years, range 16-25) transferred after growth completion from two pediatric clinics to the adult endocrine unit. Two separate analyses were performed: (i) cross-sectional analysis of hormonal status, metabolic parameters, BC, and BMD at first evaluation after transfer from pediatrics to the adult department; (ii) longitudinal analysis of BC and BMD dynamics after 3 years of GH replacement therapy (rhGH) in TP.

RESULTS

COGHD was of a congenital cause (CONG) in 50.6% subjects, tumor-related (TUMC) in 23.5%, and idiopathic (IDOP) in 25.9%. TUMC patients had increased insulin and lipids levels (P < 0.01) and lower Z score at L-spine (P < 0.05) compared to CONG and IDOP groups. Patients treated with rhGH in childhood demonstrated lower fat mass and increased BMD compared to the rhGH-untreated group (P < 0.01). Three years of rhGH after growth completion resulted in a significant increase in lean body mass (12.1%) and BMD at L-spine (6.9%), parallel with a decrease in FM (5.2%).

CONCLUSION

The effect of rhGH in childhood is invaluable for metabolic status, BC, and BMD in transition to adulthood. Tumor-related COGHD subjects are at higher risk for metabolic abnormalities, alteration of body composition, and decreased BMD, compared to those with COGHD of other causes. Continuation of rhGH in transition is important for improving BC and BMD in patients with persistent COGHD.

Impaired quality of life in growth hormone-deficient adults is independent of the altered skeletal muscle oxidative metabolism found in conditions with peripheral fatigue

CONTEXT

Growth hormone-deficient (GHD) adults often report impaired quality of life (QoL) - with fatigue, a key element. This deficit can improve following GH replacement. The basis of this response is unclear. Perturbations in skeletal muscle metabolism have been demonstrated in several conditions in which fatigue is a prominent symptom. We wished to define the role of skeletal muscle metabolism in the impaired QoL observed in patients with GHD.

OBJECTIVE

To compare in vivo skeletal muscle mitochondrial oxidative phosphorylation using phosphorus-31 magnetic resonance spectroscopy in matched untreated GHD adults, treated GHD adults and healthy volunteers.

DESIGN

Twenty-two untreated GHD adults, 23 treated GHD adults and 20 healthy volunteers were recruited at a regional centre. All patients underwent assessment of muscle mitochondrial function (τ₁/₂ PCr) and proton handling using spectroscopy. Fasting biochemical analyses and anthropometric measurement were obtained. All patients completed the QoL-AGHDA and physical activity assessment (IPAQ) questionnaires.

RESULTS

Untreated and treated GHD adults complained of significantly increased fatigue and an impaired QoL (P = 0·002) when compared to healthy controls. There was no difference in maximal mitochondrial function (P = 0·53) nor pH recovery (P = 0·38) of skeletal muscle between the three groups. Untreated GHD patients had significantly lower IGF-1 than both treated GHD and healthy volunteers (P < 0·001), but there was no association between τ₁/₂ PCr and serum IGF-1 (r = -0·13, P = 0·32).

CONCLUSIONS

The impaired QoL seen in GHD adults is not associated with the skeletal muscle spectroscopic 'footprint' of altered mitochondrial oxidative function, anaerobic glycolysis or proton clearance that are a feature of several conditions in which fatigue is a prominent feature. These data suggest that the pathophysiology of fatigue and impaired QoL in GHD may have a significant central rather than peripheral (skeletal muscle) component.

GH deficiency during the transition period: clinical characteristics before and after GH replacement therapy in two different subgroups of patients

OBJECTIVE

To study two subsets of patients with GH deficiency (GHD) during the transition period: childhood onset GHD (CO-GHD) and patients who develop GHD during the transition phase (TO-GHD) before and after GH replacement.

PATIENTS AND MEASUREMENTS

In 1340 GHD subjects from KIMS (Pfizer International Metabolic Database), CO (n=586) or TO (n=754), background characteristics, anthropometric measurements, IGF-1, lipids and quality of life (QoL) were evaluated at baseline and after 3 years of GH replacement.

RESULTS

Both groups responded similarly to GH treatment. Changes of clinical outcomes were mainly determined by their value at baseline. Onset of the disease in childhood or transition period did not appear to be a significant predictor of response in any of the clinical outcomes.

CONCLUSIONS

Age at GHD diagnosis was a significant predictor for many outcomes at baseline, but disease onset did not appear as an independent predictor concerning changes after 3 years of GH treatment. The results suggest that GH replacement during the transition period should be considered independently of the onset of the deficiency.

Prevalence and risk factors of the metabolic syndrome in young adults with childhood-onset hypopituitary growth hormone deficiency

Purpose

This study evaluated the prevalence of the metabolic syndrome (MetS) and risk factors for metabolic derangement in young adults with childhood-onset hypopituitary growth hormone deficiency (ACOHGHD).

Methods

Thirty patients with ACOHGHD who were treated with hormone-replacement therapy, aged 18 to 29 years, who visited the Seoul National University Children's Hospital between September 2009 and February 2010 were enrolled. Height, weight, waist circumference, hip circumference, and blood pressure were measured, and the clinical and hormonal features were reviewed retrospectively. We evaluated measures of metabolic derangement in the enrolled patients and in the data of healthy adults aged 20 to 29 years taken from the 2005 Korean National Health and Nutrition Examination Survey (KNHANES) as part of the National Cholesterol Education Program-the Adult Treatment Panel III.

Results

Compared with the KNHANES participants, patients with ACOHGHD had significantly large waist circumference (men and women), high systolic blood pressure (BP) (women) and diastolic BP (men), and high serum triglyceride levels (women). The duration of illness correlated significantly with central obesity (r²=0.546, P=0.003). The prevalence of MetS was 10% in patients with ACOHGHD and 2.3% in KNHANES participants. The prevalence of central obesity and MetS was higher in patients with ACOHGHD than in KNHANES participants (P<0.001 and P=0.042, respectively).

Conclusion

Abdominal obesity correlated with the duration of illness in patients with ACOHGHD. Waist circumference should be measured in the clinic to prevent MetS, particularly in patients with a long history of ACOHGHD, regardless of age or sex.

Discontinuation of growth hormone (GH) treatment during the transition phase is an important factor determining the phenotype of young adults with nonidiopathic childhood-onset GH deficiency

CONTEXT

Little is known about the impact of childhood-onset GH deficiency (GHD), in particular the duration of GH cessation during the transition phase, on adult phenotype.

OBJECTIVE

We investigated the association between the manifestations and management of GHD during childhood/adolescence and the clinical features of GHD in adulthood. DESIGN/SETTING/PATIENTS/INTERVENTION: Patients with reconfirmed childhood-onset GHD who resumed GH treatment as adults were identified from two sequential databases (n = 313). The cohort was followed up longitudinally from GH start in childhood to reinitiation of treatment in adulthood and 1 yr beyond. Analyses were performed in the total cohort and in subgroups of patients with idiopathic GHD (IGHD) and non-IGHD. The cohorts were stratified based on duration of GH cessation (short, < or = 2 yr; long, > 2 yr).

MAIN OUTCOME MEASURES

Regimen of pediatric GH administration, duration of GH interruption, IGF-I sd score, lipid concentrations, and quality of life were measured.

RESULTS

Mean duration of GH interruption was 4.4 yr. IGF-I sd score in adulthood was related to severity of childhood GHD. In non-IGHD patients, a longer duration of GH interruption was associated with a worse lipid profile (P < 0.0001). Non-IGHD patients who gained more height during childhood GH treatment reported better quality of life than those who gained less height (P < 0.05).

CONCLUSIONS

Pediatricians should tailor GH treatment, not only for its beneficial effect on growth but also for future health in adulthood. In adults with reconfirmed GHD, particularly those with non-IGHD, early recommencement of GH should be considered.

Etiology, baseline characteristics, and biochemical diagnosis of GH deficiency in the adult: are there regional variations?

Previous work has examined potential links between the etiology of GH deficiency (GHD) and the baseline characteristics of the patients including biochemical and psychometric parameters. Using an update of the KIMS pharmaco-epidemiological database (Pfizer International Metabolic Database), we addressed the question how well such results can be generalized and whether regional differences may play a role. From 30 different countries, 13 167 GH-deficient patients were included in KIMS at the data close in December 2008. In order to explore country-specific differences of baseline characteristics documented in KIMS, separate analyses of baseline characteristics of adult-onset GHD patients (n=7708) were performed for the six largest contributing European countries and the United States. This analysis revealed striking regional variations in the pathogenesis of the disease, clinical characteristics such as body mass index, and in the classical features of the metabolic syndrome such as blood pressure or lipid status between countries. Moreover, the approach to endocrine function testing was widely different between countries, as well as the distribution of etiologies of GHD. These data suggest that a complex relation between biochemical and clinical signs of GHD exists, and that the spectrum of adult GHD syndrome is influenced by regional diagnostic and clinical particularities.

Cardiovascular risk factors in hypopituitary GH-deficient adults

Design Data on lipids, body composition, and blood pressure (BP) from all published KIMS papers are summarized and compared with a literature review. Results KIMS data confirm and extend previous research showing that adults with GH deficiency (GHD) have an adverse cardiovascular risk profile. GHD patients have high levels of dyslipidemia, elevated body mass index, unfavorable waist-to-hip ratio and body composition, and a high risk of hypertension. These abnormalities are likely to explain the increased cardiovascular mortality observed in patients with hypopituitarism. When given GH replacement therapy, an improvement is seen in KIMS as well as earlier studies for lipid profile, body composition, and BP. The added value of the different KIMS papers over previous research is that KIMS involves a much larger number of patients, that lipid concentrations and IGF1 are measured in a single central laboratory, and that the effects of GH replacement therapy can be followed longer than the duration of earlier trials. By the large number of patients, KIMS gives insight into the effects of GH in different patients' subgroups such as elderly patients, patients with idiopathic GHD, patients with craniopharyngioma, patients after irradiation, and so on. In addition, KIMS has made it possible to calculate more exactly the influence of baseline parameters on these cardiovascular risk parameters and their response to GH. Conclusions Taken together, data from KIMS confirm earlier knowledge about the important benefits of GH replacement therapy, but also on the use of GH in specific subgroups such as isolated GHD, patients above 65 years, and patients after irradiation. No subgroup yet has been identified as not responding well to GH.

Assessment of quality of life in adult patients with GH deficiency: KIMS contribution to clinical practice and pharmacoeconomic evaluations

Quality of life (QoL) has emerged as an important construct that has found numerous applications across healthcare-related fields, ranging from research and clinical evaluation of treatment effects to pharmacoeconomic evaluations and global healthcare policy. Impairment of QoL is one of the key clinical characteristics in adult GHD and has been extensively studied in the Pfizer International Metabolic Database (KIMS). We provide summarized evidence on GH treatment effects for both clinical and health economic applications based on the KIMS data. The primary focus is on those aspects of QoL research that cannot be investigated in the traditional clinical trial setting, such as specific patient subgroups, cross-country comparisons and long-term follow-up. First, the impact of age, gender, disease onset, primary aetiology, extent of hypopituitarism, previous radiotherapy and obesity on QoL before and during long-term GH replacement is discussed. Secondly, the studies on QoL in relation to country-specific normative values are reviewed. Finally, health economic data derived from KIMS including both burden of disease and utility assessment are evaluated. We conclude that the wide spectrum of analyses performed on the KIMS data allows for practical application of the results not only to research and clinical practice but also to health policy and global medical decision making.