Growth hormone (GH) provocation tests and the response to GH treatment in GH deficiency

Evaluation of the growth response of children with growth hormone deficiency according to the peak growth hormone levels in provocation tests

BACKGROUND

We aimed to evaluate the relation between the peak growth hormone (GH) levels in provocation tests and response to recombinant human GH (rhGH) therapy in patients with GH deficiency (GHD).

METHODS

This was a cross-sectional, single-center, and retrospective study. A total of 135 patients under the age of 16 years who were diagnosed with GHD through insulin tolerance tests and L-DOPA stimulation tests and who received rhGH therapy for at least 2 years in the Pediatric Endocrinology Clinic of Akdeniz University Hospital between 1997 and 2021 were included in the study.

RESULTS

The patients were divided into two groups: idiopathic GHD (group I, n = 119) and multiple pituitary hormone deficiencies or organic pathology on magnetic resonance imaging (group II, n = 16). The patients in group I were classified into three subgroups according to the peak GH values in the provocation tests (group Ia: peak GH <3 μg/L, n = 34; group Ib: peak GH between 3 and 7 μg/L, n = 71; group Ic: peak GH between 7 and 10 μg/L, n = 34). The median age was 11.5 years in group I (8.8 in group Ia, 12.1 in group Ib, 12.3 in group Ib) and 8.8 years in group II. The height standard deviation score (SDS) was -2.93 in group I (-2.85 in group Ia, -2.99 in group Ib, -2.94 in group Ic) and -3.79 in group II. The median Δheight SDS was 0.61 in group I and 1.05 in group II at the end of the first year of treatment and 0.31 in group I and 0.45 in group II at the end of the second year (p = 0.005 and p = 0.074, respectively). When the subgroups of group I were compared, height SDS, Δheight SDS, and height velocity (HV) SDS were all higher in group Ia at the end of the first year of rhGH therapy (p = 0.040, p = 0.029, and p = 0.005, respectively). The height SDS was still significantly higher in group Ia (p = 0.033) while the HV SDS and Δheight SDS were similar between the groups at the end of the second year of therapy (p = 0.164 and p = 0.522, respectively). There was a statistically significant association between the first-year HV SDS and the peak GH value in provocation tests in multiple regression analyses (p<0.001). In addition, the final model revealed that height SDS and weight SDS at the start of the treatment and the first-year HV SDS are the factors with a statistically significant effect on the second-year HV SDS (p = 0.022, p = 0.001, and p<0.001, respectively).

CONCLUSION

Our findings show that the lower the GH peak in provocation tests, the better the response to treatment. The best HV was observed in the first year of rhGH therapy, and the diagnosis should be checked in those patients who had a low first-year HV and did not have a severely low GH peak in provocation tests.

Response to growth hormone according to provocation test results in idiopathic short stature and idiopathic growth hormone deficiency

PURPOSE

To investigate growth response in children with either idiopathic short stature (ISS) or growth hormone (GH) deficiency (GHD).

METHODS

The data of prepubertal GHD or ISS children treated using recombinant human GH were obtained from the LG Growth Study database. GHD children were further divided into partial and complete GHD groups. Growth response and factors predicting growth response after 1 and 2 years of GH treatment were investigated.

RESULTS

This study included 692 children (98 with ISS, 443 partial GHD, and 151 complete GHD). After 1 year, changes in height standard deviation score (ΔHt-SDS) were 0.78, 0.83, and 0.96 in ISS, partial GHD, and complete GHD, respectively. Height velocity (HV) was 8.72, 9.04, and 9.52 cm/yr in ISS, partial GHD, and complete GHD, respectively. ΔHt-SDS and HV did not differ among the 3 groups. Higher initial body mass index standard deviation score (BMI-SDS) and midparental height standard deviation score (MPH-SDS) were predictors for better growth response after 1 year in ISS and the partial GHD group, respectively. In the complete GHD group, higher Ht-SDS and BMI-SDS predicted better growth response after 1 year. After 2 years of GH treatment, higher BMI-SDS and MPH-SDS predicted a better growth outcome in the partial GHD group, and higher MPH-SDS was a predictor of good growth response in complete GHD.

CONCLUSION

Clinical characteristics and growth response did not differ among groups. Predictors of growth response differed among the 3 groups, and even in the same group, a higher GH dose would be required when poor response is predicted.

Inclusion and Withdrawal Criteria for Growth Hormone (GH) Therapy in Children with Idiopathic GH Deficiency—Towards Following the Evidence but Still with Unresolved Problems

According to current guidelines, growth hormone (GH) therapy is strongly recommended in children and adolescents with GH deficiency (GHD) in order to accelerate growth rate and attain normal adult height. The diagnosis of GHD requires demonstration of decreased GH secretion in stimulation tests, below the established threshold value. Currently, GHD in children is classified as secondary insulin-like growth factor-1 (IGF-1) deficiency. Most children diagnosed with isolated GHD present with normal GH secretion at the attainment of near-final height or even in mid-puberty. The most important clinical problems, related to the diagnosis of isolated GHD in children and to optimal duration of rhGH therapy include: arbitrary definition of subnormal GH peak in stimulation tests, disregarding factors influencing GH secretion, insufficient diagnostic accuracy and poor reproducibility of GH stimulation tests, discrepancies between spontaneous and stimulated GH secretion, clinical entity of neurosecretory dysfunction, discrepancies between IGF-1 concentrations and results of GH stimulation tests, significance of IGF-1 deficiency for the diagnosis of GHD, and a need for validation IGF-1 reference ranges. Many of these issues have remained unresolved for 25 years or even longer. It seems that finding solutions to them should optimize diagnostics and therapy of children with short stature.

Influence of biochemical diagnosis of growth hormone deficiency on replacement therapy response and retesting results at adult height

Isolated growth hormone deficiency (IGHD) is the most frequent endocrinological disorder in children with short stature, however the diagnosis is still controversial due to the scarcity of reliable diagnostic criteria and pre-treatment predictive factors of long term-response. To evaluate recombinant growth hormone (rGH) long-term response and retesting results in three different groups of children divided in accordance with the biochemical criteria of initial diagnosis. Height gain (∆HT) at adult height (AH) and retesting results were evaluated in 57 rGH treated children (M = 34, 59.6%) divided into 3 groups according to initial diagnosis: Group A (n = 25) with max GH peak at stimulation test < 8 µg/L, Group B (n = 19) between 8 and 10 µg/L and Group C (n = 13) with mean overnight GH < 3 µg/L (neurosecretory dysfunction, NSD). Retesting was carried out in all patients after at least one month off therapy upon reaching the AH. 40/57 (70.2%) patients were pre-pubertal at diagnosis and showed ∆HT of 1.37 ± 1.00 SDS, with no significant differences between groups (P = 0.08). Nonetheless, 46% patients in Group B showed ∆HT < 1SDS (vs 13% and 12% in Group A and C, respectively) and 25% children failed to reach mid-parental height (vs 6% and 0% in Group A and C, respectively). At AH attainment, IGHD was reconfirmed in 28% (7/25) and 10% (2/19) in Group A and B, respectively. A reduction of diagnostic cut-off at GH stimulation tests could better discriminate between "good" and "poor responders" and predict the persistence of IGHD through transition. Group C response and the predictive value of baseline IGF-I SDS bring back to light NSD: should we consider an underlying hypothalamic derangement when the clinical presentation is strongly consistent with IGHD but pharmacological stimulation test is normal?

Is a Two-Year Growth Response to Growth Hormone Treatment a Better Predictor of Poor Adult Height Outcome Than a First-Year Growth Response in Prepubertal Children With Growth Hormone Deficiency?

OBJECTIVE

The first year response to growth hormone (GH) treatment is related to the total height gain in GH treated children, but an individual poor first year response is a weak predictor of a poor total GH effect in GH deficient (GHD) children. We investigated whether an underwhelming growth response after 2 years might be a better predictor of poor adult height (AH) outcome after GH treatment in GHD children.

DESIGN AND METHODS

Height data of GHD children treated with GH for at least 4 consecutive years of which at least two prepubertal and who attained (near) (n)AH were retrieved from the Belgian Register for GH treated children (n = 110, 63% boys). In ROC analyses, the change in height (ΔHt) SDS after the first and second GH treatment years were tested as predictors of poor AH outcome defined as: (1) nAH SDS <-2.0, or (2) nAH SDS minus mid-parental height SDS <-1.3, or (3) total ΔHt SDS <1.0. The cut-offs for ΔHt SDS and its sensitivity at a 95% specificity level to detect poor AH outcome were determined.

RESULTS

Eleven percent of the cohort had a total ΔHt SDS <1.0. ROC curve testing of first and second years ΔHt SDS as a predictor for total ΔHt SDS <1.0 had an AUC >70%. First-year ΔHt SDS <0.41 correctly identified 42% of the patients with poor AH outcome at a 95% specificity level, resulting in respectively 5/12 (4.6%) correctly identified poor final responders and 5/98 (4.5%) misclassified good final responders (ratio 1.0). ΔHt SDS after 2 prepubertal years had a cut-off level of 0.65 and a sensitivity of 50% at a 95% specificity level, resulting in respectively 6/12 (5.5%) correctly identified poor final responders and 5/98 (4.5%) misclassified good final responders (ratio 1.2).

CONCLUSION

In GHD children the growth response after 2 prepubertal years of GH treatment did not meaningfully improve the prediction of poor AH outcome after GH treatment compared to first-year growth response parameters. Therefore, the decision to re-evaluate the diagnosis or adapt the GH dose in case of poor response after 1 year should not be postponed for another year.

Impact of BMI on peak growth hormone responses to provocative tests and therapeutic outcome in children with growth hormone deficiency

This study investigated the relationship between peak stimulated growth hormone (GH) and body mass index (BMI), as well as the impact of BMI on therapeutic response in patients with GH deficiency (GHD). A total of 460 patients were enrolled in the study. The patients were divided into four groups as per the etiology and peak GH values: idiopathic (n = 439), organic (n = 21), complete (n = 114), and partial (n = 325) GHD groups. Subsequently, they were classified as normal, overweight, or obese based on their BMI. There was no difference in BMI between complete and partial GHD. A significant negative relationship between peak GH and BMI were found. Moreover, obese GHD children had a considerably better therapeutic response in height increase and BMI decrease during 2 years of GH treatment compared to non-obese children with GHD. There was no difference between peak GH and type of GH stimulation test (GHST), except the clonidine test, which showed a much lower peak GH in obese GHD children. In conclusion, BMI had a negative impact on peak GH response, and therapeutic outcome was more favorable in the obese group. Despite no difference in GH response by type of GHST, the degree of obesity differentially affected the results.

TIMING OF GH PEAK IN BOTH GLUCAGON AND CLONIDINE TESTS IS OF MAJOR CLINICAL IMPORTANCE

Objective: To detect a possible correlation between timing of the peak value of growth hormone (GH) during stimulatory tests (STs) and the effectiveness of treatment with recombinant human growth hormone (rhGH) in children with idiopathic GH deficiency (iGHD). Methods: We retrospectively studied 92 patients with iGHD (57 boys; mean age at diagnosis: 9.93 years). Diagnosis was confirmed by 2 different STs, glucagon stimulation test (GST), and clonidine stimulation test (CST). Auxologic parameters were recorded, while observed and predicted (according to KIGS Prediction Model) height velocity during the first year of treatment and the index of responsiveness (IoR) were calculated for the prepubertal children (n = 65). Results: Atypical GST was defined as that with peak GH value at time 0 minutes, 30 minutes, 60 minutes, or 180 minutes, whereas atypical CST was defined as that with peak timing at 0 minutes, 30 minutes, or 120 minutes. Atypical GST was detected in 18 patients (19.57%). IoR was lower in the prepubertal children with atypical GST (-1.81 ± 0.67 versus -1.34 ± 0.85; P = .051). In the CST, the 18 children who had atypical timing, had significantly lower IoR (-1.86 ± 0.66 versus -1.35 ± 0.84; P = .047). When the patients were categorized according to the number of atypical tests, significant differences in the IoR were detected (-2.09 ± 0.68 with 2 atypical STs [n = 6], -1.64 ± 0.61 with 1 atypical ST [n = 16], and -1.29 ± 0.87 with no atypical ST [n = 43], P = .045). Conclusion: The presence of atypical peak GH timing during ST may be a factor that predicts lower growth hormone velocity during the first year of rhGH treatment in prepubertal children with iGHD. Abbreviations: CST = clonidine stimulation test; GH = growth hormone; GHD = growth hormone deficiency; GST = glucagon stimulation test; iGHD = idiopathic growth hormone deficiency; IoR = index of responsiveness; rhGH = recombinant human growth hormone; SDS = standard deviation scores; ST = stimulatory test.

Combined simultaneous arginine clonidine stimulation test: Timing of peak growth hormone (GH) concentration and correlation with clinical indices of GH status

BACKGROUND

The aims of this study were to determine if it is possible to truncate a combined simultaneous arginine clonidine stimulation test, and to correlate the outcome of the test with clinical indices of GH status.

METHODS

Charts of subjects who underwent a combined simultaneous arginine clonidine stimulation test between January 1, 2007 and August 31, 2016 were reviewed.

RESULTS

131/203 (64.5%) tests performed in children with growth failure demonstrated a peak GH ≥ 10 ng/ml. 6/7 (85.7%) tests performed in adolescents at the end of GH treatment had a peak GH ≥ 5 ng/ml. Among these negative tests, 97.8% had a passing GH by 120 min. 58/98 (59.1%) tests that had a sample at 150 min were negative. 3/58 (5.2%) had a passing GH level only at 150 min. Therefore, if the test were shortened to 120 min, 5.2% of normal responders would be missed. There was a weak correlation of peak GH with baseline growth velocity and serum IGF-1 z-score. A trend towards an inverse correlation between peak GH level and change in growth velocity pre- and post-GH was seen.

CONCLUSIONS

If the combined simultaneous arginine clonidine test were shortened to 120 min, 5.2% of normal responders would be missed. Although this test has not been compared to any "gold standard" GH stimulation test, the outcome of this test does correlate weakly with clinical indices of GH status and spares patients the inconvenience of sequential testing.

Pattern and Frequency of Short Stature in Albanian Children

INTRODUCTION

Short stature is defined as a standing height more than 2 standard deviations (SDs) below the mean for age and sex. While there are many medical causes for being short and having poor growth, including growth hormone deficiency, hypothyroidism, Turner syndrome, inflammatory bowel disease, kidney problems, malnutrition, etc., most children who are short are normal.

OBJECTIVES

The identification and analysis of causes and factors leading to short stature in Albanian children.

PATIENTS & METHODS

Subjects enrolled in our study were admission with "Short stature" or "Slow growth velocity" from January 2001 to January 2011 and met the criteria: length < -2 z- score and/or height velocity <-2 z- score for age and sex. They were evaluated by anthropometric measurements; biochemical panel; hormonal balance; radiological studies; and hormonal provocative tests. Statistical processing was done with Epi-Info CDC 2000 and SPSS accordingly.

RESULTS

The age of the 564 children was from 0.65-18.74 years (11.08 ± 3.28 years).

M / F

221/343 (39% /61%) respectively. The frequency of diagnoses resulted as follows: the "constitutional short stature" 211children (37.4%), "GH deficit" 155(27.5%), "genetic syndrome" 67(11.9%), "familiar short stature" 38(6.7%), "others pathology" 38(6.7%), "idiopathic short stature" 31(5.5%), "i-uterine short stature" 16(2.8%).

CONCLUSIONS

The fact that 46% of the explored children resulted positive in terms of a pathology that had caused primary or secondary growth failure, makes it necessity careful monitoring of growth and reference of the children to a specialist as fast as possible. Evidently great age of exploration indicates a weak surveillance on growth monitoring in Albania.

RECOMMENDATIONS

Assessment of the child's growth must be a routine procedure. The early identification of stature growth delay will significantly increase the early detection of any pathology.

Correlation between serum IGF-1 and blood lead level in short stature children and adolescent with growth hormone deficiency

This study aimed to investigate correlation between serum insulin-like growth factor-1 (IGF-1) and blood lead level in short stature children with growth hormone deficiency (GHD), and IGF-1 signal molecules were investigated in lead exposed rats. Our findings may provide evidence for clarifying pathogenesis of lead induced short stature in children.

METHODS

880 short stature children were recruited from clinics and divided into GHD group and idiopathic short stature (ISS) group according to the GH peak in growth hormone stimulation test. The height, body weight, serum IGF-1 level and blood lead level were determined. A rat model of lead poisoning was used to establish and western blot assay was employed to detect the phosphorylation of signaling molecules (MAPK and PI3K/Akt) related to IGF-1 signaling pathway.

RESULTS

In GHD group, the height, body weight and serum IGF-1 level were significantly lower, but the blood lead level was significantly higher than those in ISS group (P<0.05). Western blot assay confirmed that the protein expression of phosphorylated ERK1/2, JNK, p38, Akt473 and Akt308 increased significantly (P<0.01) in lead exposure rats.

CONCLUSION

Our study suggesting that reduction in IGF-1 in children with GHD is associated with blood lead level. Lead exposure may induce expression of phosphorylated MAPK and Akt signaling molecules. The activation of these molecules may influence binding of IGF-1 and tyrosine kinase receptor IGFIR to regulate cell growth via the MAPK and Akt signaling pathways, which then interfere with growth-promoting effect of IGF-1 in short children.

Growth hormone treatment adherence in prepubertal and pubertal children with different growth disorders

BACKGROUND/AIMS

Treatment of children with growth disorders with recombinant human growth hormone is necessary for improved outcomes, including final height.

METHODS

Adherence data from the Observational Study Saizen®-online, recorded with the easypod™ device collected between October 2009 and May 2011, were analyzed in pediatric patients receiving recombinant human growth hormone treatment for a variety of growth disorders.

RESULTS

Data from 75 children (46 boys, 29 girls) with different growth disorders were analyzed over a period of 343 ± 201 (SD) days. Boys and girls showed similar mean ± SD adherence rates of 90.5 ± 3.1% and 92.2 ± 10.7%, respectively. Pubertal children (n = 41) had a significantly lower adherence rate (89.1 ± 13.7%) than prepubertal children (n = 29) (96.5 ± 3.9%; p < 0.005). There were nonsignificant differences in adherence rates according to diagnosis: growth hormone deficiency (n = 48) 91.4 ± 11.0%, small for gestational age (n = 18) 91.1 ± 15.3%, Turner syndrome (n = 6) 86.0 ± 14.5%, and chronic renal failure (n = 3) 99.3 ± 1.0%, although the latter two groups were small.

CONCLUSION

Our data indicate that only a small number of pediatric patients using the easypod device had poor adherence to treatment. Further reliable adherence data are required to identify factors affecting long-term adherence in this population.

Requirement for age-specific peak cortisol responses to insulin-induced hypoglycaemia in children

OBJECTIVE

Based on adult data, a peak cortisol response ≥500 nmol/l to insulin-induced hypoglycaemia constitutes a normal. Age-specific reference ranges for basal morning cortisol have been developed for clinical use in the paediatric population. Such reference ranges are not clearly established for peak cortisol responses to insulin-induced hypoglycaemia despite limited data suggesting an effect of age on peak cortisol. The aims of this study were to assess factors affecting the cortisol response to insulin-induced hypoglycaemia in children and to determine whether the peak cortisol response was related to age.

DESIGN

The present study was a retrospective cohort study.

METHODS

Retrospective analysis of children and adolescents aged ≤18 years undergoing the insulin tolerance test with adequate hypoglycaemia was undertaken. Patients with hypopituitarism or severe hypothalamic-pituitary-adrenal axis impairment (peak cortisol value <400 nmol/l) or using systemic glucocorticoids were excluded.

RESULTS

Two hundred and twenty-three tests were analysed. Peak cortisol responses ≥500 nmol/l occurred in 183 (82%) tests. Age was negatively associated with peak cortisol responses (r=-0.15, P=0.03). A peak cortisol response <500 nmol/l was significantly less common in patients aged <12 years (9/97 (9%) vs 31/126 (25%); P=0.004). In children aged <12 years, the median (5th-95th centiles) peak cortisol values were 610 (480-806) nmol/l compared with 574 (442-789) nmol/l in children aged ≥12 years (P<0.004). Similarly, median cortisol increment was significantly higher in younger patients (301 nmol/l compared with 226 nmol/l (P=0.0004)).

CONCLUSIONS

Use of a single peak cortisol threshold in children of all ages is not appropriate and will result in overdiagnosis of adrenal insufficiency in adolescents.

Growth hormone regimens in Australia: analysis of the first 3 years of treatment for idiopathic growth hormone deficiency and idiopathic short stature

OBJECTIVE

To investigate response to growth hormone (GH) in the first, second and third years of treatment for all idiopathic GH-deficient (GHD) and idiopathic short stature (ISS) patients in Australia.

CONTEXT

Eligibility for subsidized GH treatment in Australia is determined on auxological criteria for the indication of Short Stature and Slow Growth (SSSG), which includes ISS (SSSG-ISS). The biochemical GHD (BGHD, peak GH < 10 mU/l) and SSSG indications are treated similarly: starting dose of 4·5 mg/m(2)/week with provision for incremental dosing. Some ISS patients were specifically diagnosed with familial short stature (SSSG-FSS).

DESIGN

Responses for each year of treatment for BGHD, SSSG-ISS and SSSG-FSS cohorts were compared in relation to influencing variables and with international benchmarks. The effect of incremental dosing was assessed.

PATIENTS

Australian BGHD, SSSG-ISS and SSSG-FSS patients who had completed 1, 2, or 3 years of treatment and were currently receiving GH.

MEASUREMENTS

Growth hormone dose, change in height-standard deviation score (ΔSDS) and growth velocity (GV).

RESULTS

First-year response was 2-3 times greater than that in subsequent years: ΔSDS(1st year) = 0·92, 0·50 and 0·46 for BGHD, SSSG-ISS and SSSG-FSS, respectively. Responses were similar to international reports and inversely related to age at commencement of GH. First-year GV-for-age for BGHD patients was similar to international standards for idiopathic GHD. However, girls had an inferior response to boys when treatment commenced at <6 years of age. First-year GV-for-age for SSSG-ISS/FSS patients was less than ISS standards. Dose increments attenuated the first- to second-year decline in response to BGHD but marginally improved the responses for SSSG-ISS/FSS.

CONCLUSIONS

The Australian auxology-based GH programme produces comparable responses to international programmes. A lower starting dose is offset by the initiation of treatment at younger ages. Incremental dosing does not appear optimal. A first-year dose of 6·4-6·9 mg/m(2)/week for GHD and 8·9 mg/m(2)/week for ISS with early commencement of GH treatment may be most efficacious.

The benefits of growth hormone therapy in patients with Turner syndrome, Noonan syndrome and children born small for gestational age

This review will summarize the effects of growth hormone (GH) on height, body composition, bone and psychosocial parameters in children with Turner syndrome or Noonan syndrome and those born small for gestational age. The safety of GH treatment in children with these diagnoses is also reported. Despite the reported efficacy and safety of GH in these indications, however, not all children achieve their target height potential, due in some part to poor adherence to GH therapy regimens; indeed up to 50% of children are less than fully compliant with treatment. With this in mind the present and future administration of GH therapy is discussed with respect to advances being made in the presentation of GH for injection and advances in GH injection devices. It is hoped that such progress, aimed at making the administration of GH easier and less painful for the patient will improve treatment adherence and outcome benefits.

Genetic causes and treatment of isolated growth hormone deficiency-an update

Isolated growth hormone deficiency is the most common pituitary hormone deficiency and can result from congenital or acquired causes, although the majority of cases are idiopathic with no identifiable etiology. Known genes involved in the genetic etiology of isolated growth hormone deficiency include those that encode growth hormone (GH1), growth-hormone-releasing hormone receptor (GHRHR) and transcription factor SOX3. However, mutations are identified in a relatively small percentage of patients, which suggests that other, yet unidentified, genetic factors are involved. Among the known factors, heterozygous mutations in GH1 remain the most frequent cause of isolated growth hormone deficiency. The identification of mutations has clinical implications for the management of patients with this condition, as individuals with heterozygous GH1 mutations vary in phenotype and can, in some cases, develop additional pituitary hormone deficiencies. Lifelong follow-up of these patients is, therefore, recommended. Further studies in the genetic etiology of isolated growth hormone deficiency will help to elucidate mechanisms implicated in the control of growth and may influence future treatment options. Advances in pharmacogenomics will also optimize the treatment of isolated growth hormone deficiency and other conditions associated with short stature, for which recombinant human growth hormone is a licensed therapy.

Systematic review of the clinical effectiveness of Genotropin (somatropin) in children with short stature

Genotropin (somatropin) is licensed for the treatment of children with growth hormone deficiency, Prader-Willi syndrome, Turner syndrome, chronic renal insufficiency and in children born small for gestational age. This systematic review (SR) evaluated the clinical efficacy and effectiveness of Genotropin in these conditions to inform a NICE Technology Appraisal of growth hormone for the treatment of growth failure in children. Search terms were used to search seven databases, including Medline and Embase, for English language studies. Randomised controlled trials (RCTs) or observational studies investigating Genotropin in children were included. Out of 30 RCTs identified, one reported final height data. Eleven observational studies reported final height and seven were based on the Pfizer International Growth Survey (KIGS). This SR highlights the lack of long-term RCTs reporting final height data and other important qualitative outcomes, such as quality of life. Observational data, such as those from KIGS, remain vital for informing therapy.

Observations of nonadherence to recombinant human growth hormone therapy in clinical practice

BACKGROUND

The effectiveness of all prescribed treatments is contingent on patient adherence. The reported levels of adherence to recombinant human growth hormone (r-hGH) therapy are highly variable, but it has been suggested that nonadherence might be as high as 36% to 49%.

OBJECTIVES

This commentary discusses the factors that affect long-term adherence to injection treatment, of which r-hGH therapy is a particular challenge. It also explores potential strategies to improve adherence to injection treatments in clinical practice.

METHODS

The opinion of the authors was validated and supported by published literature. A PubMed literature search was conducted in November 2006, identifying English-language articles containing key terms growth hormone, adherence, and compliance.

RESULTS

This study found that factors associated with poor adherence to injection treatments include patients' lack of understanding of their disease, patient age, chronicity of the disease, complex treatment regimens, and insufficient information on the implications of nonadherence. Strengthening the patient-physician relationship by providing the patient with a clear understanding of his/her disease and the benefits of adherence, making improvements in injection devices, and eliminating subjective illness concepts, might increase adherence to SC injection treatments, thereby reducing increasing health care costs associated with nonadherence.

CONCLUSIONS

Poor adherence to r-hGH therapy has a dual effect, in that it leads to reduced efficacy out-comes and increased health care costs. Implementing strategies to improve adherence with injection treatment might be of particular clinical benefit to patients undergoing r-hGH therapy.

Pharmacological and physiological growth hormone stimulation tests to predict successful GH therapy in children

Although the current use of growth hormone (GH) stimulation tests (GHSTs) is still subject to debate, the tests are widely used to diagnose GH deficiency. This literature review evaluates primarily the sensitivity, specificity and reliability of GHSTs and secondarily their convenience. Single pharmacological tests typically address only a single pathway in the complex physiological regulation of GH secretion and are therefore characterized by lower sensitivity, specificity and reliability than combined pharmacological tests or physiological tests. In spite of the high levels of sensitivity, specificity and reliability, physiological tests require considerably more effort to perform, from the physician as well as from the child. Therefore, a need for an alternative, convenient, physiological GHST still remains. Oral ingestion of dietary protein is convenient in practice and may induce more physiological stimulation of GH secretion, hence may be a promising valuable addition to the existing GHSTs in GH deficiency.

Diagnosis of growth hormone (GH) deficiency: comparison of pituitary stalk interruption syndrome and transient GH deficiency

Background

Most patients with childhood non-organic growth hormone (GH) deficiency (GHD) produce a normal GH peak as young adults. Our objectives were to better define this transient GHD and evaluate the factors influencing the growth response of patients with pituitary stalk interruption syndrome (PSIS).

Methods

We studied 72 prepubertal patients with a GH peak < 6.7 ng/ml after 2 stimulation tests, treated with 0.2 mg GH/kg/w for at least 3 years. Group 1 (n = 53, 4.7 ± 4.0 years) had PSIS and Group 2 (n = 19, 9.2 ± 3.0 years) had transient GHD and normal pituitary.

Results

At diagnosis, 64% of Group 1 and one Group 2 were < 5 years old. The growth rate of 59% Group 1 and two Group 2 patients was ≤ -2 SDS. The GH peak of 64% Group 1 patients and no Group 2 patients was < 3 ng/ml. The plasma insulin-like growth factor-1 of all Group 1 and all but one Group 2 patients was ≤ -2 z scores.

During the first year of GH treatment, the growth rate was ≥ 2 SDS in 81% Group 1 and 37% Group 2 patients. In Group 1, it was negatively correlated with the GH peak before treatment (P < 0.03), and with the difference between the target and adult heights (P < 0.01).

The height gain SDSs between diagnosis and adult height were 1.7 ± 1.2 in Group 1 (n = 30) and 1.08 ± 0.8 in Group 2 (n = 12, P = 0.05).

Conclusion

The factors of the growth response to GH treatment should be analysed separately for each population: with and without PSIS or other markers.

[Mathematical models for predicting growth responses to growth hormone replacement therapy]

Growth prediction models are algorithms derived from multiple regression analyses including variables that influence growth responses to GH therapy in a defined group of subjects over a defined period of time. Mathematical equations can be derived from the knowledge acquired with the relative importance of each variable, which provide objective measurements of each subject's growth potential in response to GH therapy on different situations. Therefore, these equations can be used as tools to improve evidence-based decision regarding to growth promoting treatment strategies to be used in each child, optimizing cost-effectiveness with the lowest cumulative GH dose. Several models have already been developed to predict growth responses to GH for different short stature causes, but they still have low clinical usefulness, due to their low predictive power and low prevision accuracy. This has lead to a growing interest in the addition of new variables, such as biochemical or genetic markers, which could improve prevision accuracy and then allow, in the future, GH therapy individualization according to the specific needs of each child.

Prediction of adult height in growth-hormone-treated children with growth hormone deficiency

CONTEXT

Several studies have searched for factors that significantly influence adult height (AH) of children with GH deficiency (GHD) who have been treated with biosynthetic GH, but a prediction model for AH has not yet been presented.

OBJECTIVE

Our objective was to develop models for prediction of AH, using information available at the start of GH treatment or after 1 yr of treatment.

DESIGN AND SETTING

For this retrospective study, data were collected from the National Registry of Growth Hormone Treatment in Children, which contained data of Dutch children treated with GH.

PATIENTS/INTERVENTION

Patients included males born before 1985 and females born before 1987 with either diagnosis of GHD (syndromes, tumors, and other diseases were excluded) or a maximal GH response during provocation tests of less than 11 ng/ml, treated with biosynthetic GH for at least 1 yr. To be able to use the complete group of 342 children for the development of the models, multiple imputation was used for missing values.

MAIN OUTCOME MEASURE

We assessed AH sd scores (SDS).

RESULTS

Each prediction model contained both target height SDS and current height SDS. The change in height SDS during the first year proved an important predictor for AH. In all models, addition of GH dose was not significant. The percent explained variance, after correction for overfitting, ranged from 37% (prepubertal children, prediction at start) to 60% (pubertal children, prediction after 1 yr).

CONCLUSION

The presented prediction models give accurate predictions of AH for children with GHD at start and after 1 yr of GH treatment. They are useful tools in the treatment of these children.