Growth hormone deficiency in elderly patients with hypothalamo-pituitary tumors

The accuracy of diagnostic tests for GH deficiency in adults: a systematic review and meta-analysis

CONTEXT

The diagnostic accuracy of tests used to diagnose GH deficiency (GHD) in adults is unclear.

OBJECTIVE

We conducted a systematic review and meta-analysis of studies that provided data on the available diagnostic tests.

DATA SOURCES

We searched electronic databases (MEDLINE, EMBASE, Cochrane CENTRAL, Web of Sciences, and Scopus) through April 2011.

STUDY SELECTION

Review of reference lists and contact with experts identified additional candidate studies. Reviewers, working independently and in duplicate, determined study eligibility.

DATA EXTRACTION

reviewers, working independently and in duplicate, determined the methodological quality of studies and collected descriptive, quality, and outcome data.

DATA SYNTHESIS

Twenty-three studies provided diagnostic accuracy data; none provided patient outcome data. Studies had fair methodological quality, used several reference standards, and included over 1100 patients. Several tests based on direct or indirect stimulation of GH release were associated with good diagnostic accuracy, although most were assessed in one or two studies decreasing the strength of inference due to small sample size. Serum levels of GH or IGF1 had low diagnostic accuracy. Pooled sensitivity and specificity of the two most commonly used stimulation tests were found to be 95 and 89% for the insulin tolerance test and 73 and 81% for the GHRH+arginine test respectively. Meta-analytic estimates for accuracy were associated with substantial heterogeneity.

CONCLUSION

Several tests with reasonable diagnostic accuracy are available for the diagnosis of GHD in adults. The supporting evidence, however, is at high risk of bias (due to heterogeneity, methodological limitations, and imprecision).

Influence of growth hormone on cardiovascular health and disease

Experimental and clinical studies indicate that growth hormone (GH) and insulin-like growth factor-1 (IGF-1) are involved in heart development. Impaired cardiovascular function, as recently demonstrated, could potentially reduce life expectancy both in GH deficiency (GHD) and excess. Patients with childhood- or adult-onset GHD may have both cardiac structural and functional abnormalities, i.e. reduced cardiac mass, reduced diastolic filling, and impaired left ventricular response to peak exercise. In addition, GHD patients may present with an increase in vascular intima-media thickness and a higher occurrence of atheromatous plaques that can further aggravate the hemodynamic conditions and contribute to the increased cardiovascular and cerebrovascular risk. However, some evidence has been provided to show that cardiovascular abnormalities can be partially reversed after somatropin (recombinant GH) therapy in patients with GHD. Recently, somatropin administration was shown to induce improvement in hemodynamics and clinical status in some patients with heart failure. Although these data need to be confirmed in more extensive studies, such promising results open new perspectives for somatropin therapy. The role of GH secretagogues in heart failure is still unknown.

Cardiovascular Effects of Growth Hormone Treatment: Potential Risks and Benefits

Growth hormone (GH) and insulin-like growth factor-I are involved in heart development and in maintaining cardiac structure and performance. Cardiovascular disease has been reported to reduce life expectancy both in GH deficiency (GHD) and in GH excess. Patients with GHD suffer from abnormalities of left ventricular performance, i.e. reduced diastolic filling and impaired response to peak exercise. Patients with GHD also have increased intima-media thickness at the common carotid arteries, associated with a higher occurrence of atherosclerotic plaques, which may further aggravate the haemodynamic conditions. This may contribute to increased cardiovascular and cerebrovascular risk. These cardiovascular abnormalities can be reversed, at least partially, with GH replacement therapy. In recent years, GH therapy has been used to increase cardiac mass in ischaemic or dilated cardiomyopathy, but the results have produced contradictory data.

Growth hormone and the heart

Impaired cardiovascular function has recently been demonstrated to potentially reduce life expectancy both in GH deficiency and excess. Experimental and clinical studies have supported the evidence that GH and IGF-I are implicated in cardiac development. In most patients with acromegaly a specific cardiomyopathy, characterized by myocardial hypertrophy with interstitial fibrosis, lympho-mononuclear infiltration and areas of monocyte necrosis, results in biventricular concentric hypertrophy. In contrast, patients with childhood or adulthood-onset GH deficiency (GHD) may suffer both from structural cardiac abnormalities, such as narrowing of cardiac walls, and functional impairment, that combine to reduce diastolic filling and impair left ventricular response to peak exercise. In addition, GHD patients may have an increase in vascular intima-media thickness and a higher occurrence of atheromatous plaques, that can further aggravate the haemodynamic conditions and contribute to increased cardiovascular and cerebrovascular risk. However, several lines of evidence have suggested that the cardiovascular abnormalities can be partially reversed by suppressing GH and IGF-I levels in acromegaly or after GH replacement therapy in GHD patients. Recently, much attention has been focussed on the ability of GH to increase cardiac mass suggesting its possible use in the treatment of chronic nonendocrine heart failure. In fact, GH administration can induce an improvement in haemodynamic and clinical status in some patients. Although these data need to be confirmed in more extensive studies, such promising results seem to open new perspectives for GH treatment in humans.

Does the age of onset of growth hormone deficiency affect cardiac performance? A radionuclide angiography study

BACKGROUND

GH and IGF-I seem to play a relevant role in cardiac development and performance. Long-standing GH deficiency (GHD) causes several abnormalities in cardiac structure and performance which ultimately determine an increased cardiovascular morbidity and mortality.

OBJECTIVE

To investigate whether the age of onset of GHD plays a role in determining the negative effects on the heart.

DESIGN

Open cross-sectional

PATIENTS

55 patients with adulthood-onset GHD and 36 healthy sex- and age-matched controls. Patients and controls were divided into 2 groups in line with age: 32 patients and 16 controls, were aged </= 35 years (young); while 23 patients and 20 controls were aged between 36 and 60 years (middle-aged). The estimated disease duration was similar in young (6.7 +/- 0.5 years) and middle-aged patients (8.1 +/- 1.2 years, P = 0.2).

STUDY PROTOCOL

All subjects underwent ECG, blood pressure and heart rate measurement, plasma IGF-I level assay, and equilibrium radionuclide angiography.

RESULTS

Plasma IGF-I levels were significantly lower in patients than in controls (P < 0.0001). When considered as a whole, no difference in systolic (SBP) and diastolic blood pressure (DBP) at peak exercise was found between patients and controls. However, a significant decrease of SBP at rest was found in young patients as compared to age-matched controls (P = 0.009), while a significant increase of DBP at rest was found in middle-aged patients as compared to age-matched controls (P = 0.03). In addition, in young patients, both resting (P = 0.02) and exercise heart rate (P = 0.01) were significantly lower than in controls. Diastolic filling when measured as end-diastolic volume (EVD/sec), was significantly reduced in middle-aged patients (P = 0.04). An impaired peak filling rate (PFR) (< 2.5 EDV/sec) was found in 30 patients (54.5%) and 10 controls (27.7%, chi2 = 5.3, P = 0.02): 17 young (53.1%) and 13 middle-aged patients (56.5%). A significant decrease of left ventricular (LV) ejection fraction (EF) at peak exercise was found in both patients groups (P < 0.0001) while LVEF at rest was lower only in middle-aged patients (P = 0.004). An impaired LVEF at rest (< 50%) was found in 13 patients (23.6%) and in none of controls (chi2 = 8.1, P = 0.004). The exercise induced changes in LVEF (DeltaEF) were significantly lower in both patients groups than in age-matched controls (P < 0.0001). Impaired LVEF response to exercise (< 5% increase vs. basal value) was found in 36 patients (65.4%) and in 5 controls (13.8%, chi2 = 21.3, P < 0.000): 21 young (65.6%) and 15 middle-aged patients (65.2%). The peak ejection rate (PER) was also significantly lower in young GHD patients than in controls (P < 0.001). Exercise duration and capacity were significantly reduced in both groups of GHD patients. In the patient group, age was significantly correlated with SBP and DBP levels both at rest (r = 0.612, and r = 0.516, respectively, P < 0.001) and at peak exercise (r = 0.4, P < 0.005 and r = 0.34, P < 0. 01, respectively), with exercise duration (r = - 0.383, P < 0.005) and capacity (r = - 0.355, P = 0.005). Disease duration was also correlated with IGF-I levels (r = - 0.319, P < 0.01), SBP levels at peak exercise (r = 0.352, P = 0.005), and LVEF at rest (r = - 0.254, P < 0.05). Finally, a significant correlation was found between IGF-I levels and DBP at peak exercise (r = 0.3, P < 0.05) and between GH peak at ARG + GHRH test and LVEF at rest (r = 0.232, P < 0.05). Exercise-induced changes in LVEF were significantly correlated with SBP levels at peak exercise (r = - 0.401, P < 0.005), PFR expressed as EDV/sec (r = - 0.306, P < 0.05) and SV/sec (r = - 0.292, P < 0.05). At multiple regression analysis in the patient group, age was the strongest predictor of SBP both at rest (t = 4.17, P < 0.0001) and at peak exercise (t = 2.32, P = 0.025), and capacity (t = - 2.84, P = 0.007). IGF-I levels were the strongest predictor of DBP at peak exercise (t = 2.2, P = 0.

Impaired cardiac performance in elderly patients with growth hormone deficiency

Several evidences indicate that GH and/or insulin-like growth factor I (IGF-I) are involved in the regulation of cardiovascular function. In patients with childhood and adulthood-onset GH deficiency (GHD), the impairment of cardiac performance is manifest primarily as a reduction in the left ventricular (LV) mass (LVM), inadequacy of LV ejection fraction both at rest and at peak exercise, and abnormalities of LV diastolic filling. No study has been reported to date in elderly GHD patients that investigated cardiac function. In particular, it is unknown whether cardiac function is modified in accordance with patients' age as a physiological response to aging, as in normal subjects the rate and extent of LV filling are reduced with age. This study was designed to evaluate heart morphology and function, by echocardiography and equilibrium radionuclide angiography, respectively, in rigorously selected elderly patients with GHD but without evidence of other complications able to affect cardiac performance. Eleven patients with hypopituitarism (6 men and 5 women, aged 60-72 yr) and 11 sex- age- and body mass index-matched healthy subjects entered this study. None of the patients and controls presented with or had previously suffered from other concomitant diseases, such as diabetes mellitus, coronary artery diseases, long-standing hypertension, and hyperthyroidism, which could affect cardiac function. All patients had been previously operated on via the transsphenoidal and/or transcranic route for nonfunctioning pituitary adenoma, meningioma, or craniopharyngioma, and 6 of them had been irradiated. Eight patients had FSH/LH insufficiency, 5 had TSH insufficiency, and 6 had ACTH insufficiency, appropriately replaced. All subjects were tested with the combined arginine plus GHRH test showing a GH response below 9 microg/L. No significant difference was found in plasma IGF-I levels (49.2 +/- 8.5 vs. 71.8 +/- 7.5 microg/L) between patients and controls. However, IGF-I levels were lower than the normal range in 8 patients and 3 controls. Interventricular septum thickness (9.1 +/- 0.2 vs. 9.1 +/- 0.2 mm), LV posterior wall thickness (9.1 +/- 0.2 vs. 9.0 +/- 0.2 mm), and LVM after correction for body surface area (97.6 +/- 1.8 vs. 99.9 +/- 1.5 g/m2) were similar in patients and controls. Similarly, the LV ejection fraction at rest was similar in patients and controls (57.1 +/- 2% vs. 63.2 +/- 2.5%; P = NS), and it was normal (> or = 50%) in all controls and in 10 of 11 patients. By contrast, the LV ejection fraction at peak exercise was markedly depressed in elderly GHD patients compared to age-matched controls (51 +/- 2.5% vs. 73.3 +/- 3%; P < 0.001). A normal response (> or = 5% increase compared to basal value) of LV ejection fraction at peak exercise was found in 8 controls (72.7%) and in 2 of 11 patients (18.2%). No difference was found in the peak rate of LV filling, whether peak filling rate was normalized to end-diastolic volume (2.5 +/- 0.2 vs. 2.6 +/- 0.2 end-diastolic volume/s) or stroke volume (4.3 +/- 0.3 vs. 4.0 +/- 0.3 stroke volume/s), between patients and controls. Finally, exercise duration was significantly shorter in elderly GHD patients than in age-matched controls (7.2 +/- 2.1 vs. 9.1 +/- 0.2 min; P < 0.01). In the patient group, the GH peak after arginine plus GHRH test was significantly correlated with the LV ejection fraction at rest (r = 0.822; P < 0.01), whereas IGF-I was significantly correlated with the peak rate of LV filling whether the peak filling rate was normalized to end-diastolic volume (r = -0.863; P < 0.001) or stroke volume (r = -0.616; P < 0.05) or expressed as the ratio of peak filling rate to peak ejection fraction rate (r = -0.736; P < 0.01). Disease duration was significantly correlated with heart rate at peak exercise (r = 0.614; P < 0.05) and with systolic and diastolic blood pressures both at rest (r = 0.745; P < 0.01 and r = 0.650; P < 0.05) and at peak exercise (r = 0.684; P < 0.05 and r =

Diagnostic and therapeutic uses of growth hormone-releasing substances in adult and elderly subjects

The aim of this review is to answer two questions. The first question is: is there any alternative provocative test equal to, or even better than, the insulin-tolerance test (ITT), the so-called gold standard, for the diagnosis of growth hormone deficiency (GHD) in adults and the elderly? The answer is 'yes'. In fact, when combined with arginine or pyridostigmine, growth hormone-releasing hormone (GHRH) becomes one of the most potent and reproducible tests for distinguishing patients with severe GHD from normal subjects. Owing to its tolerability and its suitability for use in the elderly, the GHRH + arginine test is the best alternative choice and is at least as sensitive as the ITT provided that appropriate cut-off limits are given. The second question is: is there any therapeutic approach alternative to recombinant human growth hormone (rhGH) for adult and elderly patients with GHD and/or for the somatopause? At present, the answer is 'no'. Growth hormone (GH)-releasing substances need the functional integrity of somatotroph cells to induce the release of growth hormone. Probably only patients with childhood-onset, isolated GHD (frequently hypothalamic-dependent) could benefit from treatment with GHRH or growth hormone secretagogues (GHS). Whenever restoration of the activity of the GH/insulin-like growth factor-1 (IGF-1) axis in the elderly would be of use, GHRH and/or GH secretagogues would be good candidates. In fact, the existence of a considerable pool of releasable growth hormone has been demonstrated in the elderly.