Cardiac effects of growth hormone in short normal children: results after four years of treatment

Effect of Growth Hormone Therapy on Pubertal Timing: Systematic Review and Meta-Analysis

INTRODUCTION

Recombinant human growth hormone (rhGH) therapy effectively increases height in various disorders of childhood growth. However, whether rhGH affects pubertal timing is unclear. We aimed to review systematically published evidence on the effect of rhGH on pubertal timing.

METHODS

Embase, MEDLINE, and Cochrane Library databases were searched until December 2021 on randomized and non-randomized controlled studies of rhGH in children.

RESULTS

Twenty-five articles (n = 1,433 children) were identified, describing 12 randomized and 13 non-randomized controlled studies in children with idiopathic short stature (ISS; 15 studies), small for gestational age (n = 6 studies), chronic renal failure (n = 3), Noonan syndrome (n = 1), and growth hormone deficiency (n = 1). Significant differences in the effects of rhGH on pubertal timing were found by clinical indication. Only among children with ISS, rhGH promoted earlier age at pubertal timing (mean difference = -0.46 years; 95% CI, -0.90 to -0.03; 9 studies; n total = 397) or higher relative risk for pubertal onset during study follow-up (1.26; 95% CI, 1.03 to 1.54; 6 studies; n total = 284).

CONCLUSIONS

Treatment with rhGH appears to promote earlier pubertal timing among children with ISS. Evidence was lacking in children with growth hormone deficiency due to the absence of studies with untreated controls.

The effect of recombinant human growth hormone therapy on left-ventricular chamber size and function in children with growth hormone deficiency

This study was designed to assess the effect of recombinant human growth hormone (rhGH) therapy on left-ventricular (LV) chamber size and function in children with idiopathic isolated growth hormone deficiency (GHD) using conventional echocardiography and tissue Doppler imaging (TDI). Thirty patients (19 boys and 11 girls) with idiopathic isolated GHD were followed-up for 12 months. Mean age of patients was 11.0 ± 2.6 years (range 6.3-15.5). At baseline and at 3, 6, and 12 months of treatment, the structure of the left ventricle was assessed by conventional echocardiography and myocardial rates and time intervals by TDI. There was a significant increase in LV mass (LVM) compared with pretreatment values. Like LVM, relative wall thickness (RWT) was also increased significantly. The significant increase in LVM indexed to body surface area and RWT became apparent at month 3 of treatment with a significant increase in LVM indexed to height(2.7) at treatment month 6. Normalized LVM increased as early month 3 of treatment, and a steady increase was observed until month 12. However, no patient had LVM > +2 standard deviation scores at month 12 of treatment. No significant differences were observed in functional parameters of the left ventricle and the interventricular septum. The results of this study showed that rhGH therapy causes an increase in myocardial mass without changing the geometry or function of the myocardium. Therefore, the increase in myocardial mass appears to be concentric, thus causing remodeling instead of hypertrophy.

Rapid cardiovascular effects of growth hormone treatment in short prepubertal children: impact of treatment duration

OBJECTIVE

Previous studies show that growth hormone (GH) treatment increases cardiac dimensions in short children with GH deficiency (GHD) and has diverse cardiac effects in children with idiopathic short stature (ISS). This study was performed to assess the effect of GH on the cardiovascular system in short children with a broad range of GH secretion and GH sensitivity/responsiveness.

DESIGN AND PATIENTS

In this prospective, multicentre study, short prepubertal children diagnosed with isolated GHD (89) or ISS (38) were followed during 2 years of GH treatment. They were randomized to receive either a standard (43 μg/kg/day) or an individualized GH dose (range 17-100 μg/kg/day) based on GH responsiveness estimated by a prediction model and distance to target height. Echocardiography, blood pressure and electrocardiography were performed at baseline, 3, 12 and 24 months.

RESULTS

Left ventricular mass (LVM) indexed to body surface area increased significantly during 2 years of GH treatment in both GHD and ISS irrespective of randomized dose. This change was already apparent at 3 months, when standard deviation scores (SDS) of wall thickness and diameter were increased. At 24 months, left ventricular diameter SDS remained increased, whereas myocardial thickness SDS returned to baseline values. There was no impairment of systolic or diastolic function. There was no correlation with treatment dose and LVM SDS at 24 months.

CONCLUSIONS

Irrespective of GH status, there was a rapid increase in LVM during GH treatment in short children. At 3 months, wall thickness and diameter were increased, whereas only diameter remained increased at 24 months.

Cardiac functions in children with growth hormone deficiency before and during growth hormone-replacement therapy

Childhood growth hormone deficiency (GHD) decreases left-ventricular (LV) mass, but impairment of cardiac function has never been documented. The objective of this study was to assess the cardiac effects of GHD and recombinant human growth hormone (rhGH) treatment using conventional echocardiography and tissue Doppler imaging. Complete two-dimensional, M-mode, pulse-wave Doppler echocardiography and pulse-wave tissue Doppler imaging were performed in 12 children (6 male and 6 female patients) with GHD at baseline and at 5.86 ± 1.61 months after rhGH therapy. Recombinant human growth hormone treatment was associated with a significant increase in LV mass index (63.8 ± 27.1 to 79.3 ± 30.3 g/m(2); P < 0.01) and LV internal dimensions (21.4 ± 2.63 to 24.0 ± 4.13 mm in systole [P = 0.03] and 36.5 ± 3.90 to 39.5 ± 4.94 mm in diastole [P < 0.01]). There were statistical differences of parameters, such as deceleration time of early peak velocity of mitral, isovolumic relaxation time, and myocardial performance index (103 ± 15.4 to 139 ± 21.2 ms [P < 0.01], 55.5 ± 9.24 to 69.2 ± 3.74 ms [P < 0.01], and 37.8 ± 4.46 to 44.9 ± 5.44% [P < 0.01], respectively). Before and during rhGH therapy, there were no significant differences in fractional shortening of the left ventricle, peak mitral, and tricuspid wave velocities with ratios determined using conventional echocardiography and tissue Doppler imaging. In children, GHD affects heart morphology by inducing a decrease in cardiac size, but it does not modify cardiac function. Recombinant human growth hormone treatment increases cardiac mass, deceleration time of early peak velocity of the mitral valve, isovolumic relaxation time, and myocardial performance index, but it does not make a difference in other parameters of conventional echocardiography and tissue Doppler imaging.

Growth hormone: health considerations beyond height gain

The therapeutic benefit of growth hormone (GH) therapy in improving height in short children is widely recognized; however, GH therapy is associated with other metabolic actions that may be of benefit in these children. Beneficial effects of GH on body composition have been documented in several different patient populations as well as improvements in lipid profile. Marked augmentation of bone mineral density also seems evident in many pediatric populations. Some of these benefits may require continued therapy past the acquisition of adult height. With long-term therapy of any kind, the adverse consequences of treatment should also be considered. Fortunately, long-term GH treatment seems to be safe and well-tolerated. This review describes the long-term metabolic effects of GH treatment in the pediatric population and considers how these may benefit children who are treated with GH.

Cardiac status after childhood growth hormone treatment of Turner syndrome

CONTEXT

In Turner syndrome (TS), GH treatment is well established. Data on cardiac status after discontinuation of treatment are scarce. This study aimed to assess biventricular size and function in TS at least 6 months after discontinuation of GH treatment.

METHODS

TS patients and healthy women prospectively underwent cardiac magnetic resonance imaging. Ventricular two-dimensional tomographic cine data were acquired to obtain biventricular volume, mass, and ejection fraction. Atrioventricular valve flow measurements were performed using a two-dimensional flow-sensitized sequence. Flow velocity curves were calculated and indices of biventricular diastolic filling were derived.

RESULTS

Thirty-one patients [mean (sd) age 20 (2) yr, body surface area 1.75 (0.15) m(2), 5 (2) yr after GH discontinuation] and 23 normal control women [age 21 (2) yr, body surface area 1.80 (0.13) m(2)] were included. Compared with controls, patients had smaller mean end-diastolic volumes [right ventricle (RV), 84 (11) ml/m(2) vs. 79 (10), P = 0.02; left ventricle (LV), 81 (10) vs. 72 (9), P < 0.001], end-systolic volumes [RV 38 (7) ml/m(2) vs. 36 (6), P = 0.04; LV 34 (5) vs. 29 (4), P < 0.001], and stroke volumes [RV 46 (6) ml/m(2) vs. 43 (6), P = 0.03; LV, 47 (7) vs. 44 (4), P = 0.02]. Patients had a higher mean heart rate [79 (13) beats/min vs. 71 (10), P < 0.05]. Biventricular ejection fraction, mass, cardiac output, and diastolic filling pattern were comparable.

CONCLUSION

After discontinuation of GH treatment TS patients showed no myocardial hypertrophy and well-preserved biventricular function. Ventricular volumes were smaller in Turner patients, compared with controls, whereas mean heart rate was higher. These last observations may be part of the natural development in TS and not linked to GH treatment, which at this point we consider safe.

Recombinant human growth hormone treatment for dilated cardiomyopathy in children

OBJECTIVE

Dilated cardiomyopathy (DCM) is one of the most common causes of heart failure among children and is often progressive despite maximal medical therapy. Heart failure is characterized by a number of neurohormonal abnormalities, including derangements in the growth hormone (GH)/insulin-like growth factor-1 (IGF-1) signaling axis. Decreased serum levels of GH, which acts on cardiac myocytes primarily through IGF-1, are associated with impaired myocardial growth and function, which can be improved with restoration of GH/IGF-1 homeostasis. In animal models and among human adults with heart failure attributable to DCM, treatment with GH results in acquisition of left ventricular (LV) mass and improved LV function, through a combination of mechanisms. We undertook this study to determine the effects of recombinant human GH on LV function and mass among children with stable LV dysfunction attributable to DCM.

METHODS

We performed a prospective, single-center, randomized, partially blinded, crossover trial among children 1 to 19 years of age with DCM and cardiac dysfunction of > or =6-month duration. After enrollment, patients were randomly assigned to receive treatment for 6 months with either conventional therapy (determined by the patient's primary cardiologist) plus recombinant human GH (0.025-0.04 mg/kg per day), administered as daily subcutaneous injections, or conventional therapy alone. Patients were then crossed over to the other treatment strategy for 6 months. The primary outcome measure was change in LV shortening fraction (SF). Other echocardiographic indices of LV function, somatic growth, and somatotropic/thyroid hormone levels were also monitored.

RESULTS

Only 8 of an intended 15 patients were enrolled, because of a combination of factors. Two patients withdrew during the study as a result of declining LV function requiring transplantation. LV SF did not change significantly during GH treatment, although both LV SF and LV SF z score were higher 6 months after cessation of GH treatment than at baseline. LV ejection fraction increased during GH therapy to a degree that approached significance. Height and weight percentiles for age increased significantly during GH therapy and remained higher 6 months after treatment. Annualized height velocity during GH treatment (13.7 +/- 3.3 cm/year, >97th percentile for all patients) was significantly higher than that after GH discontinuation (3.2 +/- 3.5 cm/year). Serum levels of IGF-1 and IGF-binding protein-3 were significantly higher after 6 months of GH treatment and 6 months after discontinuation of GH treatment than at baseline. There were no adverse events related to GH treatment.

DISCUSSION

In this prospective, single-center, randomized, partially blinded, crossover trial, recombinant human GH was administered to 8 pediatric patients with stable chronic heart failure secondary to DCM. Because of unanticipated difficulty enrolling eligible patients, the study was underpowered to detect changes in our primary outcome measure of the magnitude we projected. Nevertheless, we did observe several notable cardiovascular effects of GH treatment, including a trend toward improved LV ejection fraction during the course of GH treatment and significantly improved LV SF, SF z score, and LV end systolic stress z score 6 months after discontinuation of GH treatment (relative to baseline values). Given the fact that levels of IGF-1, the primary myocardial effector of GH signaling, remained significantly higher 6 months after GH treatment than at baseline, the improvement in LV functional indices 6 months after discontinuation of therapy may represent progression or perpetuation of a GH treatment effect. In addition to its cardiovascular effects, GH therapy was associated with significant acceleration of somatic growth. The benefits of GH were not associated with significant attributable side effects, although 2 patients developed progressive LV dysfunction during the study and underwent cardiac transplantation.

Left ventricular mass and function in children with GH deficiency before and during 12 months GH replacement therapy

OBJECTIVE

This open, prospective study was designed to evaluate the effect of GH deficiency (GHD) on left ventricular (LV) mass (LVM) and performance, by echocardiography, and on lipid profile during childhood.

SUBJECTS

Twelve prepubertal children with GHD (eight boys and four girls) aged 8.1 +/- 1.7 years were studied before and after 6 and 12 months of GH replacement therapy at a dose of GH of 30 micro g/kg/day. Twelve healthy children sex-, height-, weight- and body surface area-matched with the patients, served as controls.

METHODS

Echocardiography was performed at study entry and after 12 months both in GHD children and in controls. Only in GHD children, echocardiography was repeated also after 6 months of GH replacement. In all subjects, we measured LV posterior wall thickness (LVPWT), LV end-diastolic diameter (LVEDD), LVM index (LVMi), LV systolic and diastolic function.

RESULTS

At study entry, LVPWT (5.3 +/- 0.8 vs. 6.2 +/- 1.1 mm, P < 0.05), LVEDD (34.0 +/- 2.4 vs. 36.7 +/- 2.1 mm, P < 0.007) and LVMi (47.0 +/- 6.9 vs. 59.6 +/- 9.5 g/m2, P < 0.005) were significantly lower in GHD children than in controls. Lipid profile, heart rate, blood pressure, LV systolic function and indices of ventricular filling were similar in patients and controls. After 12 months of GH replacement therapy, LVPWT (6.1 +/- 0.7 mm, P < 0.0005), LVEDD (38.8 +/- 4.3 mm, P < 0.002) and LVMi (71.5 +/- 12.7 g/m2, P < 0.0005) significantly increased in GHD children compared to pretreatment values. In particular, after 12 months of therapy GHD children achieved a normal LVMi when compared to controls (60.7 +/- 8.6, P = ns). LVMi increase was significantly correlated with the increase in IGF-I level (r = 0.49; P < 0.004). LV systolic performance, diastolic filling and blood pressure did not change significantly during GH therapy. After 12 months of treatment, the atherogenic index, measured as total/high-density lipoprotein-cholesterol ratio (2.7 +/- 0.8) was significantly lower than both pretreatment (3.4 +/- 0.3, P < 0.03) and control values (3.8 +/- 1.1, P < 0.04).

CONCLUSIONS

GH deficiency in children affects heart morphology, by inducing a significant decrease in cardiac size, but does not modify cardiac function and lipid profile. Twelve months of GH replacement treatment normalizes cardiac mass, and reduces the atherogenic index.

Recombinant human growth hormone increases thyroid hormone-binding sites in recovering severely burned children

Thyroxine (T4), Tri-iodothyronine (T3), and total serum protein levels are reduced in severely burned children. T4 and T3 are carried on serum transport proteins via thyroid hormone-binding sites (THBS). Treatment of bums with recombinant human growth hormone (rhGH) increases albumin (Alb) and prealbumin (PreAlb), which bind nearly 30% of circulating T4 and T3. This study investigated the effect of rhGH on THBS sites in burned children. Records of 11 acutely burned children with a total body surface area burned >40% who were randomized to either a daily subcutaneous injection of rhGH at 0.05 mg/kg/day or placebo for 6 months after discharge from hospital were reviewed. Thyroxine uptake percentage (TU%), Total T4 levels (TT4), free thyroxine index, Alb and PreAlb, and height and weight measurements taken at discharge and 6 months later were compared in both groups. In the six children who received rhGH, mean TU% had decreased from 41 +/- 1 to 33 +/- 1% by 6 months postdischarge, (P < 0.001), mean TT4 increased from 5.8 +/- 0.3 to 8.1 +/- 0.8 microg/dL, (P < 0.02), mean Alb increased from 2.0 +/- (0.6) to 3.5 +/- (0.1) g/dL (P < 0.0001), and mean PreAlb increased from 8.7 +/- 0.7 to 16.5 +/- 2.1 mg/dL, (P < 0.006). There were no significant changes in the five children in the placebo (control group), and height and weight did not significantly change in either group. rhGH significantly increases THBS in severely burned children, possibly through increases in serum Alb and PreAlb. The increases in circulating thyroxine observed in this group may be involved in the attenuation of growth arrest.

Exogenous growth hormone: a new therapy for dilated cardiomyopathy

Heart failure is an epidemic within the United States and, despite current medical therapy, carries a high mortality rate. Growth hormone and insulin-like growth factor-1 have known direct effects on the cardiovascular system. Improvement in contractility, reduction in wall stress, and increase in cardiac performance have been noted in animal experiments. Furthermore, preliminary data from human trials are encouraging. This report outlines the biology of growth hormone, the experimental and human data to support clinical trials of growth hormone treatment, and the outcome of trials reported to date.

M-mode echocardiographic evaluation of systolic function, LV volume and mass in children on growth hormone therapy

Since abnormal endogenous growth hormone (GH) secretion in adults is associated with cardiac dysfunction, it is important to ensure that GH therapy in children and adolescents does not cause similar effects. Forty-two growth hormone-deficient children (Group 1) (19 girls, 23 boys) were evaluated. Six girls and seven boys were prepubertal with a mean age of 6.65 yr (range 4.37-9.73 yr). Twenty-nine were pubertal (13 girls, 16 boys), mean age 13.57 yr (range 10.08-16.76 yr). The patients had been on long-term GH therapy for 34.97 +/- 18.78 months with an average weekly dose of 17.61 IU/m2/wk. The mean height SDS was -2.85 +/- 1.22 for boys and -2.5 +/- 0.64 for girls at the onset of therapy, and at the time of examination -1.8 +/- 1.32 for the boys and 1.87 +/- 0.94 for the girls. Thirty-four normal control subjects (Group 2) matched for age, sex and body size were also studied. Left ventricular volume (LV), mass and systolic function [shortening fraction (FS)] were evaluated by two-dimensional guided M-mode echocardiography. Blood pressure was also measured. No differences in blood pressure were observed between patients and controls. There was no correlation of GH dose and duration of therapy with LV measurements. No significant differences were found between Group 1 and Group 2. These observations suggest that long term administration of GH does not produce adverse cardiac effects in GH deficient children. Nevertheless, longer follow-up studies are still needed to confirm the safety of long-term rhGH treatment.

The effects of long-term growth hormone treatment on cardiac left ventricular dimensions and blood pressure in girls with Turner's syndrome. Dutch Working Group on Growth Hormone

OBJECTIVE

To assess the effects of long-term growth hormone (GH) treatment for short stature on left ventricular (LV) dimensions and systemic blood pressure (BP) in girls with Turner's syndrome without clinically relevant cardiac abnormalities.

STUDY DESIGN

LV dimensions measured by echocardiography and systemic BP were assessed before and during 7 years of GH treatment in 68 girls with Turner's syndrome participating in a randomized dose-response study. These previously untreated girls, age 2 to 11 years, were randomly assigned to 1 of 3 GH dosage groups: group A, 4 IU/m(2)/d; group B, first year 4 IU/m(2)/d, thereafter 6 IU/m(2)/d; group C, first year 4 IU/m(2)/d, second year 6 IU/m(2)/d, thereafter 8 IU/m(2)/d. After the first 4 years, girls >/=12 years of age began receiving 17beta-estradiol, 5 microg/kg body weight per day, for induction of puberty.

RESULTS

At baseline the LV dimensions of almost every girl were within the normal range, and the mean SD scores were close to zero. During 7 years of GH treatment, the growth of the left ventricle was comparable to that of healthy girls. No signs of LV hypertrophy were found. Before the start of GH treatment, mean BP was within the normal range but significantly higher than in healthy control subjects. Diastolic BP and systolic BP were above the 90th percentile in 23% and 28% of the girls, respectively. After 7 years of treatment, these percentages were 14% and 36%, respectively (not significantly different from baseline). The SD score of the diastolic BP showed a small decrease after 7 years of treatment. The growth of the left ventricle and the development of BP were not different between the GH dosage groups.

CONCLUSIONS

Long-term GH treatment, even at dosages up to 8 IU/m(2)/d, does not result in LV hypertrophy or hypertension in girls with Turner's syndrome. Continued observation into adulthood is recommended to monitor the further development of the relatively high BP and to ensure that GH treatment has no long-term negative effect on the heart.

Is growth hormone good for the heart?

Growth hormone (GH), probably acting indirectly through locally produced insulin-like growth factor I, stimulates myocardial hypertrophy and increases myocyte contractility. In experimental models insulin-like growth factor I appears to be a key regulator of ventricular hypertrophy. Many adults with growth hormone deficiency (GHD) have reduced left ventricular mass, a lower ejection fraction, and reduced exercise tolerance. Elevated serum lipid levels, increased visceral fat, and early atheroma formation may contribute to an increased mortality rate from cardiovascular disease in these persons, but GH replacement therapy appears to correct many of these abnormalities. GH excess (acromegaly) results in cardiac hypertrophy that can progress to cardiac failure. Treatment with octreotide at least partially reverses cardiac hypertrophy and dysfunction. GH treatment may induce beneficial cardiac hypertrophy in adults without GHD who have dilated cardiomyopathy. Significant cardiac dysfunction has not been reported in children with GHD who are treated with GH, nor have adverse cardiac effects been reported with GH in short children without GHD, including those with Turner syndrome. We now have extensive experience with the therapeutic use of GH in children with cardiac structural abnormalities (e.g., Turner and Noonan syndromes, congenital heart disease), and such use appears to be safe. Furthermore, cardiac complications of GH in children without cardiac disease are rare. Continued observation to ensure that GH therapy has no long-term effects on cardiac anatomy or function in children is necessary.