In Australia human recombinant growth hormone (hGH) therapy is subsidized by the Australian Government under the Pharmaceutical Benefits Scheme (PBS) through special arrangements made under section 100 of the National Health Act 1953.
The GH program as of Sep 1st 2015 is administered through the Department of Human Services as an authority prescription through Medicare by paediatric endocrinologists or general paediatricians in consultation with a paediatric endocrinologist. Under this new system patients will be charged the standard dispensing fee by the pharmacist for each 3 month GH script ( i.e. $37.70 for general patients and $6.10 for concessional patients).
The Specific Aims of GH therapy for children are as follows:
- To promote short-term catch-up growth and enhance long-term linear growth in children of short stature;
- To allow children to achieve their familial genetic adult height potential, and where possible to achieve a final height within the normal population range;
- To correct neonatal hypoglycaemia due to GH deficiency;
- To ensure GH therapy is safe; and
- To improve linear growth and body composition for patients with Prader-Willi Syndrome.
There are several diagnostic and auxological (growth) criteria under which a child with short stature and slow growth velocity may qualify for hGH through the government program. Theseinclude the following categories:
- Short short slowly growing (SSGC) (with normal GH secretion)
- Biochemical GH deficiency
- Cranial Irradiation or Intracranial lesion (e.g. craniopharyngioma) in remission associated with GH deficiency
- Turner Syndrome (TS) and SHOX deficiency
- Chronic Renal Failure
The following eligible categories where the child's height is not required to be below the 1st centile (i.e. severe degree of short stature with the lower the centile being shorter compared with an average height which is on the 50th centile). These include children with:
- Neonatal or infant hypoglycaemia (low blood sugar) due to GH deficiency
- Prader Willi Syndrome in which hGH is used to improve body composition as well as growth. Morbid obesity is however an exclusion criterion.
- GH Deficiency associated with Central Precocious Puberty
- Chronic Renal Failure in which approval can be granted if child is below 25th height centile
- Turner syndrome (TS) in which child has to be below 95th centile for TS height chart.
- GHD associated with an intracranial lesion or past history of cranial irradiation
For specific details about the auxological criteria and application process refer to the GH program website (see below).
If the child applying for GH though the program fulfills all the diagnostic and growth criteria, in general, approval is granted by the GH program, though there is now no avenue of appeal as before through an expert panel of 5 paediatric endocrinologists in the GH Advisory Committee. This approval process may take up to two weeks. It is important to avoid unnecessary delays in approval to include all required information as requested in the application forms which are available on the DHS GH program website below.
In general 12 months of growth data are necessary for all applications, though 6 months of data can be submitted if the case is deemed more urgent in an older child category. Though there is no official lower age limit for applying for GH therapy, but as at least a year of growth measurements are required, children have to be at least 1 year old before an application is accepted. The only exception to this is if a child qualifies under the hypoglycaemia GH deficiency criterion. Thus in general children rarely receive GH therapy outside the hypoglycaemia criterion unless at least 2 to 3 years of age.
Reapplication for further supplies of GH is made every 6 months and approval for further supplies is granted if response criteria are met (see guidelines for these details). In general this involves demonstration of an improvement on growth velocity and height centile, or body composition (e.g. waist circumference or body mass index) in children with Prader-Willi syndrome (PWS).
The dose of GH is calculated on the child's body surface area, which is calculated from the height and weight of the child expressed as meters squared or m2. Under the new authority script system the doses of GH up to maximal for each specific category can be prescribed if felt indicated by the treating physician. However generally a starting dose of 4.5mg/m2/week is adequate for children with proven GH Deficiency though larger starting doses can be requested and are generally required for children with non-GH deficient causes of short stature like Turner syndrome or intrauterine growth retardation and chronic renal insufficiency. It is recommended that monitoring of GH dosage be undertaken by serum IGF-1 measurements at least yearly, if not 6 monthly, especially after any dose increase.
Dose increases up to the maximal allowable dose can be requested every 6 months if the growth response is felt to be inadequate. Maximal doses of GH in general equal 7.5mg/m2/week, except for children with Turner syndrome, SHOX deficiency or chronic renal failure in whom a maximal dose of 9.5mg/m2/week can be used.There is increasing evidence that the best response to GH therapy is during the first 2 years of treatment with higher starting doses.
GH therapy may be stopped by the program if the child is no longer responding on a maximal GH dose i.e. if height velocity <4 cm/year; height centile not improving or if the bone age has reached near final adult height (15.5 years in boys and 13.5 years in girls). For children under the SSGC, TS, SHOX deficiency criteria GH may be stopped when they reach the 10th centile for adult height -boys: 167.7 cm; girls: 155 cm.
In children with PWS once they reach a bone age of 15.5 years in boys and 13.5 years in girls GH can be continued until 18 years of age at a lower dose.
Presently in Australia children with proven biochemical GH deficiency or hypopituitarism are not eligible for GH beyond near final adult height (ie. bone age 15. 5 years in boys and 13.5 years in girls). This is despite several international guidelines and studies recommending its use in adolescents and adults with severe GH deficiency, who have associated GH deficiency-related symptoms and complications (e.g. osteoporosis and abnormal body composition) and poor quality of life measures.
In general GH therapy is safe but adverse events can occur, so monitoring forside-effects through regular clinical, radiological (annual bone age xray) and if necessary biochemical monitoring (serum IGF-1 and thyroid function tests) is advised.
The Australasian Paediatric Endocrine Group (APEG) OzGrow national database, inco-operation with the DOHA GH program, conducts important clinical research in all children receiving GH in Australia. Prior to Sep 1st 2015 parents applying for GH therapy for their child were asked to consider consenting to their child's and family's deidentified data being entered into the Ozgrow database to facilitate research into growth disorders and GH therapy in Australia. It is hoped the Ozgrow research program can be continued once an agreement has been made with the DHS under the new GH program.
For further information the reader is advised to visit the GH Program website
Associate Professor Gary M. Leong
Dept of Paediatric Endocrinology and Diabetes
Lady Cilento Children’s Hospital South Brisbane, Queensland
and The University of Queensland