Growth hormone replacement therapy for growth hormone-deficient adults

Detecting growth hormone misuse in athletes

Athletes have been misusing growth hormone (GH) for its anabolic and metabolic effects since the early 1980s, at least a decade before endocrinologists began to treat adults with GH deficiency. Although there is an ongoing debate about whether GH is performance enhancing, recent studies suggest that GH improves strength and sprint capacity, particularly when combined with anabolic steroids. The detection of GH misuse is challenging because it is an endogenous hormone. Two approaches have been developed to detect GH misuse; the first is based on the measurement of pituitary GH isoforms and the ratio of 22-kDa isoform to total GH. The second is based on the measurement of insulin like growth factor-I (IGF-I) and N-terminal propeptide of type III procollagen (P-III-NP) which increase in a dose-dependent manner in response to GH administration. Both methodologies have been approved by the World Anti-Doping Agency (WADA) and have led to the detection of a number of athletes misusing GH.

Regulation of whole body energy homeostasis with growth hormone replacement therapy and endurance exercise

We hypothesized that network analysis is useful to expose coordination between whole body and myocellular levels of energy metabolism and can identify entities that underlie skeletal muscle's contribution to growth hormone-stimulated lipid handling and metabolic fitness. We assessed 112 metabolic parameters characterizing metabolic rate and substrate handling in tibialis anterior muscle and vascular compartment at rest, after a meal and exercise with growth hormone replacement therapy (GH-RT) of hypopituitary patients (n = 11). The topology of linear relationships (| r | ≥ 0.7, P ≤ 0.01) and mutual dependencies exposed the organization of metabolic relationships in three entities reflecting basal and exercise-induced metabolic rate, triglyceride handling, and substrate utilization in the pre- and postprandial state, respectively. GH-RT improved aerobic performance (+5%), lean-to-fat mass (+19%), and muscle area of tibialis anterior (+2%) but did not alter its mitochondrial and capillary content. Concomitantly, connectivity was established between myocellular parameters of mitochondrial lipid metabolism and meal-induced triglyceride handling in serum. This was mediated via the recruitment of transcripts of muscle lipid mobilization (LIPE, FABP3, and FABP4) and fatty acid-sensitive transcription factors (PPARA, PPARG) to the metabolic network. The interdependence of gene regulatory elements of muscle lipid metabolism reflected the norm in healthy subjects (n = 12) and distinguished the regulation of the mitochondrial respiration factor COX1 by GH and endurance exercise. Our observations validate the use of network analysis for systems medicine and highlight the notion that an improved stochiometry between muscle and whole body lipid metabolism, rather than alterations of single bottlenecks, contributes to GH-driven elevations in metabolic fitness.

Growth hormone, IGF-I and insulin and their abuse in sport

There is widespread anecdotal evidence that growth hormone (GH) is used by athletes for its anabolic and lipolytic properties. Although there is little evidence that GH improves performance in young healthy adults, randomized controlled studies carried out so far are inadequately designed to demonstrate this, not least because GH is often abused in combination with anabolic steroids and insulin. Some of the anabolic actions of GH are mediated through the generation of insulin-like growth factor-I (IGF-I), and it is believed that this is also being abused. Athletes are exposing themselves to potential harm by self-administering large doses of GH, IGF-I and insulin. The effects of excess GH are exemplified by acromegaly. IGF-I may mediate and cause some of these changes, but in addition, IGF-I may lead to profound hypoglycaemia, as indeed can insulin. Although GH is on the World Anti-doping Agency list of banned substances, the detection of abuse with GH is challenging. Two approaches have been developed to detect GH abuse. The first is based on an assessment of the effect of exogenous recombinant human GH on pituitary GH isoforms and the second is based on the measurement of markers of GH action. As a result, GH abuse can be detected with reasonable sensitivity and specificity. Testing for IGF-I and insulin is in its infancy, but the measurement of markers of GH action may also detect IGF-I usage, while urine mass spectroscopy has begun to identify the use of insulin analogues.

Preliminary development of the new individualized HDQoL questionnaire measuring quality of life in adult hypopituitarism

OBJECTIVES

The objectives were (1) to report the preliminary development of the Hormone Deficiency-dependent Quality of Life (HDQoL) questionnaire, a new individualized questionnaire in which respondents rate personally applicable domains for importance and impact of hormonal deficiency and its treatment; (2) to evaluate the HDQoL's psychometric properties for adults with hypopituitarism including growth hormone deficiency (GHD).

METHODS

Internal consistency reliability, aspects of validity, and sensitivity to change of the HDQoL were investigated in: (1) a cross-sectional survey of 157 adults with treated or untreated GHD; (2) a randomized, placebo-controlled study of 3 months' growth hormone (GH) withdrawal from 12 of 21 GH-treated adults.

RESULTS

Thirteen of the original 18 HDQoL domains were relevant and important for GH-deficient adults. The shorter 13-item HDQoL had excellent internal reliability (Cronbach's alpha coefficient = 0.914, n = 109), and was sensitive to sex differences (cross-sectional study): women perceived worse present QoL than men [t(149.8) = 2.33, P = 0.021]. The HDQoL was sensitive to change (GH-withdrawal study) with a significant between-group difference in change in domain scores for things I can do physically[t(16) = 2.47, P = 0.025, 2-tailed], patients withdrawn from GH reporting greater negative impact of hormone deficiency on this domain at end-point. Qualitative work resulted in the addition of seven new HDQoL domains, including energy and bodily pain.

CONCLUSION

The HDQoL, although at an early stage of development, proved useful in identifying expected changes following GH withdrawal. The extended 20-item version is recommended for further evaluation in assessing the impact of hypopituitarism on QoL.

Psychometric properties of two measures of psychological well-being in adult growth hormone deficiency

Background

Psychometric properties of two measures of psychological well-being were evaluated for adults with growth hormone deficiency (GHD): the General Well-being Index, (GWBI) – British version of the Psychological General Well-being Index, and the 12-item Well-being Questionnaire (W-BQ12).

Methods

Reliability, structure and other aspects of validity were investigated in a cross-sectional study of 157 adults with treated or untreated GHD, and sensitivity to change in a randomised placebo-controlled study of three months' growth hormone (GH) withdrawal from 12 of 21 GH-treated adults.

Results

Very high completion rates were evidence that both questionnaires were acceptable to respondents. Factor analyses did not indicate the existence of useful GWBI subscales, but confirmed the validity of calculating a GWBI Total score. However, very high internal consistency reliability (Cronbach's alpha = 0.96, N = 152), probably indicated some item redundancy in the 22-item GWBI. On the other hand, factor analyses confirmed the validity of the three W-BQ12 subscales of Negative Well-being, Energy, and Positive Well-being, each having excellent internal reliability (alphas of 0.86, 0.86 and 0.88, respectively, N from 152 to 154). There was no sign of item redundancy in the highly acceptable Cronbach's alpha of 0.93 (N = 148) for the whole W-BQ12 scale. Whilst neither questionnaire found significant differences between GH-treated and non-GH-treated patients, there were correlations (for GH-treated patients) with duration of GH treatment for GWBI Total (r = -0.36, p = 0.001, N = 85), W-BQ12 Total (r = 0.35, p = 0.001, N = 88) and for all W-BQ12 subscales: thus the longer the duration of GH treatment (ranging from 0.5 to 10 years), the better the well-being. Both questionnaires found that men had significantly better overall well-being than women. The W-BQ12 was more sensitive to change than the GWBI in the GH-Withdrawal study. A significant between-group difference in change in W-BQ12 Energy scores was found [t(18) = 3.25, p = 0.004, 2-tailed]: patients withdrawn from GH had reduced energy at end-point. The GWBI found no significant change.

Conclusion

The W-BQ12 is recommended in preference to the GWBI to measure well-being in adult GHD: it is considerably shorter, has three useful subscales, and has greater sensitivity to change.

Intra-operative diagnosis of hypopituitarism in a patient undergoing radical nephrectomy

A 43-year-old woman presented for elective radical nephrectomy. After induction of anaesthesia, she developed hypotension that failed to respond to standard treatment measures. Her core temperature decreased to 34 degrees C in spite of active warming. She required very low concentrations of anaesthetic agents to maintain an adequate depth of anaesthesia for abdominal surgery. After excluding the common causes of hypotension, the possibility of subclinical hypopituitarism was considered and subsequently confirmed.

Psychological effects of withdrawal of growth hormone therapy from adults with growth hormone deficiency

OBJECTIVE

Growth hormone (GH) is known to be required for physical well-being. Although it is also widely believed to be important for quality of life (QoL) and psychological health, there is less supportive evidence. The objective of this study was to investigate the psychological effects of discontinuation of GH replacement from adults with severe GH deficiency (GHD).

DESIGN

A double-blind, placebo-controlled trial in which GH replacement therapy was discontinued for 3 months from 12 of 21 GH-deficient adults, where nine continued with GH replacement.

PATIENTS

GH-treated adults (10 men, 11 women), all with severe GHD (peak GH < 7.7 mU/l on provocative testing), mean age 44.9 years (range 25-68 years).

MEASUREMENTS

Semi-structured interviews were given at baseline and end-point plus questionnaires that included a new hormone-deficiency specific, individualized, QoL questionnaire (HDQoL), the General Well-being Index (GWBI), the Well-being Questionnaire (W-BQ12), the Short-Form 36 health status questionnaire (SF-36), the Nottingham Health Profile (NHP) and the General Health Questionnaire (GHQ).

RESULTS

Three months after baseline the serum total IGF-I of placebo-treated patients fell from normal, age-related levels (mean 26.6 +/- 13.2 nmol/l) to levels indicative of severe GHD (11.6 +/- 6.6 nmol/l) (P<0.001). Psychological symptoms of GH withdrawal, reported in interviews at end-point by placebo-treated patients, included decreased energy, and increased tiredness, pain, irritability and depression. Patients who believed they knew which treatment they had received correctly identified the treatment (GH or placebo) at end-point (chi2=11.25, P<0.01). Significant between-treatment-group differences in change scores were found for SF-36 General Health (P<0.01), W-BQ12 Energy (P<0.01) and HDQoL do physically (P<0.05), indicating reduced general health, reduced energy and greater perceived impact of hormone deficiency on physical capabilities in the placebo-treated group at end-point relative to GH-treated patients.

CONCLUSION

Withdrawal of GH treatment from adults with severe GH deficiency has detrimental psychological effects.

Growth hormone therapy in adults

Growth hormone (GH) is classically linked with linear growth in childhood but continues to have important metabolic actions throughout life. GH deficiency in adulthood causes a distinct syndrome with significant morbidities. These include increased total and visceral fat, decreased muscle mass and aerobic capacity, affective disturbances, abnormal lipids, and increased vascular mortality, all of which are ameliorated with GH replacement. The possibility of adult GH deficiency (AGHD) should always be considered in individuals with a history of childhood GH deficiency or significant hypothalamic-pituitary damage, and the diagnosis should then be confirmed by biochemical testing. Adult GH dosing is much lower than that in pediatric practice, as appropriate for physiologic reconstitution. Hormonal side effects are minimized by stepwise dose titration. Lingering concerns remain regarding the possibility of increased cancer risk with long-term treatment, but this hazard has not been unequivocally demonstrated. Compared with AGHD, there is much less information about GH replacement in other diseases or in normal aging, or about the use of supraphysiologic GH doses to treat catabolic states. In critical illness, high-dose GH therapy has proven clearly harmful, and the balance of risks and benefits of GH administration in most adult contexts other than AGHD has not been defined.

Long-term growth hormone replacement therapy in hypopituitary adults

Growth hormone deficiency (GHD) in the adult has now been fully recognised as a clinical entity characterised by abnormal body composition, osteopenia, impaired quality of life, cardiac dysfunction and an adverse lipid profile. While short-term studies of GH replacement have demonstrated irrefutably a favourable effect on all if not most features of GHD, data on long-term administration spanning more than 2 years are still scarce. Experience of GH replacement up to 5 to 10 years indicate that the beneficial effects on body composition, predominantly a decrease in body fat and an increase in lean mass, is maintained during treatment. Long-term GH therapy also increases muscle strength and exercise performance. All data, with one exception, are consistent with a significant increase in bone mass during prolonged GH therapy. The most distinct effect on bone was observed in the worst affected individuals and in males. Improvement in quality of life is documented shortly after initiation of GH replacement and is maintained during long-term studies. This may explain the reduction in days of sick leave seen during GH therapy. The beneficial effect on cardiovascular risk factors is sustained over a prolonged period of time, revealing a reduction in intima wall thickness, and an improvement in serum lipid levels and clotting parameters. The increase in lipoprotein(a) levels with GH therapy in some studies may be disturbing, but difficulties in measuring this parameter and inconsistencies between the different studies makes it difficult to estimate its real impact. No data are yet available to show that GH replacement will normalise or even improve mortality rate and fracture rate. Adverse events associated with GH replacement therapy are mainly secondary to fluid retention as a result of excess dose administration. This can be adequately prevented by monitoring GH replacement according to serum insulin-like growth factor (IGF)-I levels. From what is currently known, GH replacement does not increase the prevalence of diabetes mellitus, and does not induce new neoplasms or recurrence of the primary brain tumour; however, longer follow-up studies are needed to provide definitive answers. In conclusion, it appears not only that long-term GH replacement therapy in adults with GHD is a procedure that can be safely used, but that GH replacement should be considered as a possible life-long therapy in order to maintain its benefits.

Evaluation of two health status measures in adults with growth hormone deficiency

OBJECTIVE

To evaluate the psychometric properties of two health status measures for adults with growth hormone deficiency (GHD): Nottingham Health Profile (NHP) and Short-Form Health Survey (SF-36).

DESIGN

(1) A cross-sectional survey of adults with treated or untreated GHD to assess reliability and validity of the questionnaires. (2) A randomized, placebo-controlled study of 3 months' GH withdrawal from GH-treated adults to assess the sensitivity of the questionnaires to change.

PATIENTS

(1) A cross-sectional survey of 157 patients with severe GHD (peak GH < 10 mU/l on provocative testing), mean age 48.9 years (range 23-70 years), who had either received GH replacement therapy for at least 6 months immediately prior to the study or had not received GH treatment in the previous 6 months. (2) GH treatment was withdrawn from 12 of 21 GH-treated adults, all with severe GHD (peak GH < 7.7 mU/l on provocative testing), mean age 44.9 years (range 25-68 years).

MEASUREMENTS

The NHP and SF-36 were used once in the cross-sectional survey, but twice in the GH-withdrawal study, at baseline and end-point (after 3 months).

RESULTS

(1) Cross-sectional survey. Both questionnaires had high internal consistency reliability with subscale Cronbach's alphas of > 0.73 (NHP) and > 0.78 (SF-36). Calculation of an NHP Total Score, occasionally reported in the literature, was shown to be inadvisable. Overall, patients with GHD were found to have significantly worse perceived functioning than the UK general population in SF-36 subscales of General Health, Bodily Pain, Social Functioning, Physical Functioning, Role-Emotional, Role-Physical, and Vitality. Although neither questionnaire found significant differences between GH-treated and non-GH-treated patients, there were correlations with duration of GH treatment (P < 0.01) for GH-treated patients in SF-36 Mental Health (r = 0.29, N = 87) and SF-36 Vitality (r = 0.33, N = 88), indicating improvement with increasing treatment duration. The SF-36 was also more sensitive than the NHP to sex differences: men had significantly better health status compared with women (P < 0.05) in all SF-36 subscales but Mental Health, but only in one NHP subscale (Physical Mobility). (2) GH-withdrawal study. Significant between-group differences in change were found in SF-36 General Health [t(17) = 2.76, P = 0.013, two-tailed] and SF-36 Mental Health [t(17) = 2.41, P = 0.027, two-tailed]: patients withdrawn from GH reported reduced general health and mental health at end-point. The NHP found no significant change.

CONCLUSIONS

The SF-36 is a better measure than the NHP of health status of people with GH deficiency because of its greater discriminatory power, with ability to detect lesser degrees of disability. It also has superior sensitivity to some subgroup differences and superior sensitivity to change compared with the NHP. The SF-36 is highly acceptable to respondents, and has very good internal consistency reliability. The SF-36 is recommended to measure the health status of adults with GH deficiency.

Recombinant human growth hormone: old and novel uses

Recent studies of the growth hormone insulinlike growth factor I (IGFI) axis suggest that these hormones are involved in several physiologic processes, in addition to growth. Thus, several lines of evidence indicate an increasingly important role for recombinant human growth hormone as a part of the modern therapeutic armamentarium. In addition to the treatment of children with growth hormone deficiency, administration of growth hormone appears to be of considerable benefit to girls with Turner syndrome, children with chronic renal failure, and adults with growth hormone deficiency or human immunodeficiency virus (HIV) wasting syndrome. Moreover, its therapeutic use is being investigated in other conditions, such as children with idiopathic short stature, the healthy elderly, and the critically ill. However, long-term surveillance among growth hormone recipients is needed to fully evaluate its risk-benefit profile.

How to diagnose hypopituitarism. Learning the features of secondary hormonal deficiencies

Hypopituitarism has many causes and various clinical presentations. Diagnosis depends on history taking, clinical suspicion, and an understanding of the hypothalamic-pituitary-target organ axes for proper interpretation of laboratory data. In the patient described in the case report, amenorrhea and inability to lactate were early clinical clues to a possible pituitary problem, but she felt otherwise fairly well over the years and did not seek evaluation. Thyroid-function tests showed normal thyrotropin measurements, but they were inappropriately low for the low T4 concentrations, indicating pituitary thyrotropin deficiency. Given the patient's obstetric history and overall clinical course, hypopituitarism resulting from postpartum pituitary necrosis was suspected. Magnetic resonance imaging of the pituitary was performed, and she was treated with glucocorticoids, T4 replacement, and estrogen-progesterone replacement. We expected her to do well. In general, the long-term outlook for patients with hypopituitarism is excellent, once the problem is diagnosed. Clinical signs and symptoms should be completely relieved by adequate hormone-replacement therapy, and with proper long-term follow-up and special attention during intercurrent illness, there should be no adverse outcomes.

Current and potential therapeutic uses of growth hormone and insulin-like growth factor I

The accepted and potential uses of GH and IGF-I are summarized in Table 1. In general, the research on the therapeutic uses of IGF-I is at a much earlier state of development compared with GH The use of GH in the treatment of children with GH deficiency is well accepted, and its use in the treatment of short stature of renal failure also is widely accepted. The FDA has approved the use of GH in children with short stature caused by GH insufficiency and renal failure. The use of GH in patients with Turner syndrome has not been approved by the FDA, although it has been approved in several other countries. The use of GH for the treatment of adults with GH deficiency is approved in several countries but it is not approved in the Unites States. With the exception of the cases with GHIS, the use of IGF-I as a therapeutic agent cannot yet be regarded as of proven usefulness. The potential uses of GH and IGF-I are an area of active investigation and will continue to enlighten our understanding of human disease and disorders of growth.

New peptide and protein drugs

A view is presented on a number of recent developments, the present state and the perspectives, especially from a pharmacotherapeutic viewpoint, for peptide and protein drugs. The expanding use and the increasing experience create new pharmacotherapeutic modalities. Peptide and protein drugs comprise among others proteins isolated from human sources, and peptides and proteins made by biotechnology including monoclonal antibodies, recombinant human hormones, cytokines and growth factors. In the field of vaccine development also innovation is taking place. Optimal application schemes of these drugs may not have been reached and (clinical) pharmacists should contribute to the optimization. Since recombinant technology has abolished scarcity for a number of these drugs--especially 'physiological' substances--special ethical problems regarding an unlimited application or expansion of the indications may arise.