Comparison of weight- vs body surface area-based growth hormone dosing for children: implications for response

Comparison of growth response and adverse reaction according to growth hormone dosing strategy for children with short stature: LG Growth Study

OBJECTIVE

Growth hormone (GH) dosage in children is conventionally determined either by body weight (BW) or body surface area (BSA). However, there is no consensus on the calculation method for proper GH treatment dose. We aimed to compare growth response and adverse reactions between BW- and BSA-based GH treatment doses for children with short statures.

DESIGN

Data from 2284 GH-treated children were analyzed. Distributions of BW- and BSA-based GH treatment doses and their association with growth response parameters, including changes in height, height standard deviation score (SDS), body mass index (BMI), and safety parameters, such as changes in insulin-like growth factor (IGF)-I SDS and adverse events, were investigated.

RESULTS

The mean BW-based doses were close to the recommended dose's upper limit in participants with GH deficiency and idiopathic short stature, while they were below the recommended dose in patients with Turner syndrome (TS). As age and BW increased, BW-based dose decreased, whereas BSA-based dose increased. Gain in height SDS was positively associated with BW-based dose in the TS group and negatively associated with BW in all groups. Despite having a lower BW-based dose, the overweight/obese groups had a higher BSA-based dose and higher frequencies of children with high IGF-I and adverse events than those of the normal-BMI group.

CONCLUSIONS

In children of older age or with high BW, BW-based doses can be overdosed in terms of BSA. and BW-based dose positively correlated with height gain only in the TS group. BSA-based doses represent an alternative dosing strategy in children who are overweight/obese.

Pediatric characteristics and the dose of propofol for sedation during radiological examinations: a retrospective analysis

OBJECTIVE

The present study aimed to investigate patients' characteristics that can affect the dose of propofol required to sedate children undergoing imaging.

METHODS

In this retrospective, observational study, we reviewed medical records of children aged 0 to 18 years who were classified as having American Society of Anesthesiologists status 1 or 2 and they underwent imaging under propofol sedation between January 2011 and August 2016. Collected data included patients' demographics, propofol doses, duration of sedation, and complications. Regression analysis was performed to determine patients' characteristics that may affect the dose of propofol required to induce sedation.

RESULTS

A total of 925 patients were included. Simple linear regression showed that the dose of propofol was correlated with age, height, weight, and body surface area. Using the results of multiple linear regression, the following formula was used to estimate the dose of propofol (mg) for sedation: 0.75 + 0.14 × age (months) + 45.82 × body surface area (m²).

CONCLUSION

A child's age, height, and body surface area should be considered when deciding the induction dose of propofol. Additionally, the formula that we have proposed can be used to estimate the dose of propofol required to induce sedation in children undergoing imaging.

Diagnosis, Genetics, and Therapy of Short Stature in Children: A Growth Hormone Research Society International Perspective

The Growth Hormone Research Society (GRS) convened a Workshop in March 2019 to evaluate the diagnosis and therapy of short stature in children. Forty-six international experts participated at the invitation of GRS including clinicians, basic scientists, and representatives from regulatory agencies and the pharmaceutical industry. Following plenary presentations addressing the current diagnosis and therapy of short stature in children, breakout groups discussed questions produced in advance by the planning committee and reconvened to share the group reports. A writing team assembled one document that was subsequently discussed and revised by participants. Participants from regulatory agencies and pharmaceutical companies were not part of the writing process. Short stature is the most common reason for referral to the pediatric endocrinologist. History, physical examination, and auxology remain the most important methods for understanding the reasons for the short stature. While some long-standing topics of controversy continue to generate debate, including in whom, and how, to perform and interpret growth hormone stimulation tests, new research areas are changing the clinical landscape, such as the genetics of short stature, selection of patients for genetic testing, and interpretation of genetic tests in the clinical setting. What dose of growth hormone to start, how to adjust the dose, and how to identify and manage a suboptimal response are still topics to debate. Additional areas that are expected to transform the growth field include the development of long-acting growth hormone preparations and other new therapeutics and diagnostics that may increase adult height or aid in the diagnosis of growth hormone deficiency.

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.

Growth hormone prescribing and initial BMI SDS: Increased biochemical adverse effects and costs in obese children without additional gain in height

Background

Recombinant human growth hormone (rhGH) treatment in children is usually prescribed using actual body weight. This may result in inappropriately high doses in obese children.

Methods

Retrospective audit of all paediatric patients treated with rhGH 2010–14 at a tertiary paediatric hospital in the UK. Change in height SDS and IGF-I SDS during the first year of treatment was stratified by initial BMI SDS in a mixed cohort, and a subgroup of GH deficient (GHD) patients. Alternative doses for those BMI SDS ≥2.0 (Obese) were calculated using BSA, IBW and LBW.

Results

354 patients (133 female) received rhGH, including 213 (60.2%) with GHD. Obesity was present in 40 patients (11.3%) of the unselected cohort, and 32 (15.0%) of the GHD cohort. For GHD patients, gain in height SDS was directly related to BMI SDS, except in obese patients (p<0.05). For both the entire cohort, and GHD patients only, IGF-1 SDS was significantly higher in obese patients (p<0.0001 for both groups). Cross sectional data identified 265 children receiving rhGH, 81 (30.5%) with a BMI-SDS ≥1.75. Alternate prescribing strategies for rhGH prescribing in obese patients suggest a saving of 27% - 38% annually.

Conclusions

Gain in IGF-I SDS is greater in obese children, and is likely to be related to relatively higher doses of rhGH. Additional gain in height was not achieved at the higher doses administered to obese children. Alternative dosing strategies in the obese patient population should be examined in rigorous clinical trials.

Low dose growth hormone treatment in infants and toddlers with Prader-Willi syndrome is comparable to higher dosage regimens

OBJECTIVE

Evaluate benefit and risk of low dose growth hormone treatment (GHT, 4.5mg/m²/week) in very young children with Prader-Willi Syndrome (PWS).

DESIGN

Prospective longitudinal clinical intervention.

METHODS

We evaluated 31 infants (aged 2-12months) and 42 toddlers (13-24months) from the PWS-OZGROW database for height, weight and BMI using the World Health Organization standard deviation scores (SDS_WHO) and PWS specific BMI (SDS_PWS), bone age, insulin-like growth factor 1 (IGF-I) levels and adverse events over 3years of GHT.

RESULTS

At commencement of GHT infants had a lower BMI SDS_WHO (-0.88 vs 0.40) than toddlers, while toddlers had a lower height SDS_WHO (-1.44 vs -2.09) (both P<0.05). All increased height SDS_WHO (2year delta height infants +1.26 SDS, toddlers+1.21 SDS), but infants normalised height sooner, achieving a height SDS of -0.56 within 1year, while toddlers achieved a height SDS of -0.88 in two years. BMI SDS_WHO increased, while BMI SDS_PWS decreased (both P<0.0001) and remained negative. The GHT response did not differ with gestation (preterm 23%) or genetic subtype (deletion vs maternal uniparental disomy). Bone age advancement paralleled chronological age. All children had low serum IGF-I at baseline which increased, but remained within the age-based reference range during GHT (for 81% in first year). Four children had spinal curvature at baseline; two improved, two progressed to a brace and two developed an abnormal curve over the observation period. Mild to severe central and/or obstructive sleep apnoea were observed in 40% of children prior to GHT initiation; 11% commenced GHT on positive airway pressure (PAP), oxygen or both. Eight children ceased GHT due to onset or worsening of sleep apnoea: 2 infants in the first few months and 6 children after 6-24months. Seven resumed GHT usually after adjusting PAP but five had adenotonsillectomy. One child ceased GHT temporarily due to respiratory illness. No other adverse events were reported. Two children substantially improved their breathing shortly after GHT initiation.

CONCLUSION

Initiation of GHT in infants with 4.5mg/m²/week was beneficial and comparable in terms of auxological response to a dose of 7mg/m²/week. Regular monitoring pre and post GH initiation assisted in early detection of adverse events. IGF-I levels increased with the lower dose but not excessively, which may lower potential long-term risks.

Short stature and hypoparathyroidism in a child with Kenny-Caffey syndrome type 2 due to a novel mutation in FAM111A gene

Background

Hypoparathyroidism in children is a heterogeneous group with diverse genetic etiologies. To aid clinicians in the investigation and management of children with hypoparathyroidism, we describe the phenotype of a 6-year-old child with hypoparathyroidism and short stature diagnosed with Kenny-Caffey syndrome (KCS) Type 2 and the subsequent response to growth hormone (GH) treatment.

Case presentation

The proband presented in the neonatal period with hypocalcemic seizures secondary to hypoparathyroidism. Her phenotype included small hands and feet, hypoplastic and dystrophic nails, hypoplastic mid-face and macrocrania. Postnatal growth was delayed but neurodevelopment was normal. A skeletal survey at 2 years of age was suggestive of KCS Type 2 and genetic testing revealed a novel de novo heterozygous mutation c.1622C > A (p.Ser541Tyr) in FAM111A. At 3 years and 2 months, her height was 80cms (SDS −3.86). She had normal overnight GH levels. GH therapy was commenced at a dose of 4.9 mg/m²/week for her short stature and low height velocity of 5cms/year. At the end of the first and second years of GH treatment, height velocity was 6.5cms/year and 7.2cms/year, respectively with maximal dose of 7.24 mg/m²/week.

Conclusion

This case highlights the phenotype and the limited response to GH in a child with genetically proven KCS type 2. Long-term registries monitoring growth outcomes following GH therapy in patients with rare genetic conditions may help guide clinical decisions regarding the use and doses of GH in these conditions.

Early cessation and non-response are important and possibly related problems in growth hormone therapy: An OZGROW analysis

OBJECTIVE

To investigate growth hormone (GH) treatment and treatment cessation with respect to efficacy and efficiency. To identify factors that best classify or predict cessation type: completed treatment (CT), early cessation (EC), or non-response (NR).

DESIGN

Observational study (1990-2013) of the Australian GH Program comparing CT, EC, and NR groups with respect to demographic, clinical, and response criteria. All patients treated for GH deficiency (GHD; 909), short stature and slow growth (SSSG; 2144), and Turner Syndrome (TS; 626) were included. Information was retrieved from the OZGROW database.

RESULTS

51.9% of patients were EC, 40.7% CT and 7.4% NR.Median treatment durations for NR patients were often longer than patients who completed treatment. EC and NR groups were both associated with poor growth response with males overrepresented.Socioeconomic status differentiated NR (higher) and EC (lower) groups.

CONCLUSIONS

EC was observed at very high rates and appears, generally, to be a little-recognised but frequent problem in GH therapy.EC and delayed recognition of NR may be interrelated being differentiated by the decision to cease or continue treatment following poor response.Poor treatment compliance is likely a major causal factor in EC.Strategies to address poor response and compliance have been developed, however, given the scale of these problems, it may be that long acting GH formulations or individualized treatment need consideration.

Comparison of body surface area versus weight-based growth hormone dosing for girls with Turner syndrome

BACKGROUND/AIMS

Growth Hormone (GH) dosage in childhood is adjusted for body size, but there is no consensus whether body weight (BW) or body surface area (BSA) should be used. We aimed at comparing the biological effect and cost-effectiveness of GH treatment dosed per m2 BSA in comparison with dosing per kg BW in girls with Turner syndrome (TS).

METHODS

Serum IGF-I, GH dose, and adult height gain (AHG) from girls participating in two Dutch and five Swedish studies on the efficacy of GH were analyzed, and the cumulative GH dose and costs were calculated for both dose adjustment methods. Additional medication included estrogens (if no spontaneous puberty occurred) and oxandrolone in some studies.

RESULTS

At each GH dose, the serum IGF-I standard deviation score remained stable over time after an initial increase after the start of treatment. On a high dose (at 1 m2 equivalent to 0.056-0.067 mg/kg/day), AHG was at least equal on GH dosed per m2 BSA compared with dosing per kg BW. The cumulative dose and cost were significantly lower if the GH dose was adjusted for m2 BSA.

CONCLUSION

Dosing GH per m2 BSA is at least as efficacious as dosing per kg BW, and is more cost-effective.