3 The technology
3.1 There are four preparations of GH available in the UK for the treatment of adults: Genotropin (Pharmacia), Humatrope (Lilly), Norditropin (Novo Nordisk) and Saizen (Serono). Each product is produced by recombinant DNA technology and has a sequence identical to that of human GH.
3.2 GH is licensed for replacement therapy in adults with severe growth hormone deficiency. Patients with severe GH deficiency in adulthood are defined as patients with known hypothalamic pituitary abnormality and at least one known deficiency of another pituitary hormone excluding prolactin. These patients should undergo a single diagnostic test in order to diagnose the presence of GH deficiency. In patients with childhood onset isolated GH deficiency (no evidence of hypothalamic pituitary abnormality or cranial irradiation), two diagnostic tests should be recommended, except for those having low IGF-1 (a marker of GH response) concentrations (standard deviation score less than -2) who may be considered for one test.
3.3 Treatment is self-administered by a daily subcutaneous injection. The initial dose is 0.2–0.3 mg (0.6–0.9 IU) daily (typically 0.27 mg [0.8 IU] daily). For the first 2–3 months dosage adjustments are made after monthly assessments of serum levels of IGF-1, and in response to the presence of adverse effects, until a maintenance dose is achieved. The currently used median maintenance dose is 0.4 mg (1.2 IU) daily. GH requirements may decrease with age.
3.4 Side effects may include headache, arthralgia (joint pain), myalgia (muscle pain), fluid retention (peripheral oedema), mild hypertension, carpal tunnel syndrome, visual problems, nausea and vomiting, paraesthesia, antibody formation, and reactions at the injection site. Benign intracranial hypertension is a rare complication.
3.5 GH treatment is contraindicated in people with any evidence of tumour activity, in critically ill patients (for example, after complications following open heart or abdominal surgery, multiple trauma, acute respiratory failure or similar conditions) and also in patients with known hypersensitivity to GH or to any of the excipients. GH treatment is also contraindicated during pregnancy and lactation. In patients with tumours, anti-tumour therapy must be completed before starting GH therapy.
3.6 The cost of treatment depends on the dose, which is determined by the weight/size of the patient as well as the individual GH reserve. The cost of GH (excluding VAT; British National Formulary [BNF] March 2003) is £23.18 per mg for Genotropin and Norditropin and £22.87 per mg for Humatrope and Saizen,. The average annual cost of GH treatment is around £3350 per patient. The cost of treatment reduces with age because the GH requirement decreases as people get older. Costs may vary in different settings because of negotiated procurement discounts.