Benign intracranial hypertension and recombinant growth hormone therapy in Australia and New Zealand

Advances in differential diagnosis and management of growth hormone deficiency in children

Growth hormone (GH) deficiency (GHD) in children is defined as impaired production of GH by the pituitary gland that results in growth failure. This disease might be congenital or acquired, and occurs in isolation or in the setting of multiple pituitary hormone deficiency. Isolated GHD has an estimated prevalence of 1 patient per 4000-10,000 live births and can be due to multiple causes, some of which are yet to be determined. Establishing the correct diagnosis remains key in children with short stature, as initiating treatment with recombinant human GH can help them attain their genetically determined adult height. During the past two decades, our understanding of the benefits of continuing GH therapy throughout the transition period from childhood to adulthood has increased. Improvements in transitional care will help alleviate the consequent physical and psychological problems that can arise from adult GHD, although the consequences of a lack of hormone replacement are less severe in adults than in children. In this Review, we discuss the differential diagnosis in children with GHD, including details of clinical presentation, neuroimaging and genetic testing. Furthermore, we highlight advances and issues in the management of GHD, including details of transitional care.

Assessment of the Pharmacokinetics, Pharmacodynamics, and Safety of Single Doses of TV-1106, a Long-Acting Growth Hormone, in Healthy Japanese and Caucasian Subjects

TV‐1106 is a human serum albumin genetically fused to recombinant human growth hormone, designed to provide a long‐acting alternative to daily growth hormone (GH) injections in patients with GH deficiency. This study investigated the pharmacokinetics, pharmacodynamics, and safety of single subcutaneous doses of TV‐1106 (7.5, 15, 50, and 100 mg) in Japanese (n = 44) and caucasian (n = 44) healthy subjects. TV‐1106 pharmacokinetics and pharmacodynamics were comparable in Japanese and caucasian populations. TV‐1106 demonstrated relatively slow absorption (median t_max, 10–30 hours) and a mean elimination half‐life of 26–36 hours. Apparent clearance and volume of distribution decreased with increasing TV‐1106 doses in both populations and appeared to increase more than dose proportionality across the tested doses. Insulin‐like growth factor‐1 (IGF‐1) and IGF binding protein‐3 (IGFBP‐3) increased in a dose‐related manner, with maximum responses observed at 33–96 and 42–109 hours, respectively. IGF‐1 and IGFBP‐3 returned to baseline values at 168 hours following 7.5 and 15 mg of TV‐1106, and 336 hours following 50 and 100 mg of TV‐1106. TV‐1106 appeared safe in both populations. There was no evidence of differences in pharmacokinetics, pharmacodynamics, or safety of TV‐1106 between Japanese and caucasian populations. The data also demonstrate long‐acting growth hormone properties of TV‐1106 and support its potential for once‐weekly dosing.

Pseudotumor Cerebri in a Child with Idiopathic Growth Hormone Insufficiency Two Months after Initiation of Recombinant Human Growth Hormone Treatment

Purpose. To report a rare case of pseudotumor cerebri (PTC) in a child two months after receiving treatment with recombinant human growth hormone (rhGH) and to emphasize the need of close collaboration between ophthalmologists and pediatric endocrinologists in monitoring children receiving rhGH. Methods. A 12-year-old boy with congenital hypothyroidism started treatment with rhGH on a dose of 1,5 mg/daily IM (4.5 IU daily). Eight weeks later, he was complaining of severe headache without any other accompanying symptoms. The child was further investigated with computed tomography scan and lumbar puncture. Results. Computed tomography scan showed normal ventricular size and lumbar puncture revealed an elevated opening pressure of 360 mm H₂O. RhGH was discontinued and acetazolamide 250 mg per os twice daily was initiated. Eight weeks later, the papilledema was resolved. Conclusions. There appears to be a causal relationship between the initiation of treatment with rhGH and the development of PTC. All children receiving rhGH should have a complete ophthalmological examination if they report headache or visual disturbances shortly after the treatment. Discontinuation of rhGH and initiation of treatment with acetazolamide may be needed and regular follow-up examinations by an ophthalmologist should be recommended.

Prolonged Intracranial Hypertension after Recombinant Growth Hormone Therapy due to Impaired CSF Absorption

We experienced a case of a Japanese boy who developed intractable idiopathic intracranial hypertension (IIH) during growth hormone (GH) treatment. At the age of 4 yr, the boy was diagnosed with idiopathic growth hormone deficiency, and recombinant human GH replacement was initiated. Nine months after initiation of the GH therapy, he began to complain of headache, but papilledema was not observed. His headache persisted thereafter, and right esotropia occurred 10 mo after the initiation of GH therapy, at which time papilledema was detected. No other neurological abnormalities were detected, and the findings of computed tomography and magnetic resonance imaging were normal. In a cerebrospinal fluid (CSF) examination, the pressure was markedly elevated to 450 mmH₂O, but no other abnormality was recognized. Impaired CSF absorption was detected using the pressure-volume index technique. The CSF levels of GH and insulin-like growth factor I were not increased. GH therapy was withdrawn after it was suggested that the IIH was associated with the GH therapy, but the headache persisted. The intracranial hypertension did not respond to diuretics, and prednisolone was only transiently effective. Although the funduscopic findings were normalized, increased CSF pressure was still observed. For over 2 yr, repeated lumbar puncture was necessary to protect against visual defect. IIH is an uncommon adverse event during GH therapy, but it must be considered carefully.

Double adverse drug reaction: Recombinant human growth hormone and idiopathic intracranial hypertension - acetazolamide and metabolic acidosis: a case report

A 9-year-old girl, treated for growth hormone deficiency, developed bitemporal progressive headache, diplopia, acute comitant esotropia and visual loss 3 months after starting recombinant growth hormone. An increased intracranial pressure was revealed by examination of ocular fundus and lumbar puncture, and the absence of other causes, ruled out through a brain scan, led to the diagnosis of idiopathic intracranial hypertension.

Recombinant growth hormone was discontinued and acetazolamide started up to 30 mg/kg/die without any clinical improvement but developing metabolic acidosis. The switch to intravenous dexamethasone (0.4 mg/kg/die) led to a dramatic clinical improvement after only 1 day, then confirmed by examination of ocular fundus and visual evoked potentials. Currently, there are no evidence-based guidelines for the management of intracranial hypertension, and even though acetazolamide is recognized as the first-line drug, its efficacy and safety have not been proven: some patients might not respond and others will present unacceptable side-effects. Therefore we suggest the use of corticosteroids in intracranial hypertension when acetazolamide is inefficient or intolerable.

Headache, idiopathic intracranial hypertension and slipped capital femoral epiphysis during growth hormone treatment: a safety update from the KIGS database

BACKGROUND

Several uncommon adverse effects may be related to growth hormone (GH) treatment. Three potential side effects, headache, idiopathic intracranial hypertension (IIH) and slipped capital femoral epiphysis (SCFE), will be discussed. Data from 57,968 children in the KIGS (Pfizer International Growth Study database) were analyzed to determine the effects of recombinant human GH (Genotropin) on these side effects. The diagnostic groups were idiopathic GH deficiency (IGHD) (n = 27,690), congenital GHD (CGHD) (n = 2,547), craniopharyngioma (n = 1,155), cranial tumours (n = 2,203), Turner syndrome (TS) (n = 6,092), idiopathic short stature (ISS) (n = 5,286), small for gestational age (SGA) (n = 2,973), chronic renal insufficiency (CRI) (n = 1,753) and Prader-Willi syndrome (PWS) (n = 1,368).

RESULTS

Total incidence (per 100,000 treatment years) of headache was 793.5 (n = 569). The incidence was significantly higher in the groups of patients with craniopharyngiomas, CGHD and cranial tumours than in the other diagnostic groups (p < 0.05 for all). IIH occurred in 41 children resulting in a total incidence (per 100,000 treatment years) of 27.7. The incidence (per 100,000 treatment years) was significantly lower in patients with IGHD (12.2) than in those with TS (56.4) (p = 0.0004), CGHD (54.5) (p = 0.0064), PWS (68.3) (p = 0.0263) and CRI (147.8) (p < 0.001). No cases of IIH were reported in the ISS group of patients. The median duration from onset of GH therapy to IIH ranged from 0.01 to 1.3 years in various diagnostic groups. SCFE was observed in a total of 52 children resulting in a total incidence (per 100,000 treatment years) of 73.4. The incidence (per 100,000 treatment years) was significantly lower in patients with IGHD (18.3) and in those children with ISS (14.5) than in the TS (84.5), cranial tumours (86.1) and craniopharyngioma groups (120.5) (p < 0.05 for all). No cases of SCFE were reported in the SGA and PWS groups. The median duration from onset of GH therapy to SCFE ranged from 0.4 to 2.5 years.

CONCLUSIONS

The incidences of IIH and SCFE in this analysis are lower than the values reported in previous KIGS analyses and comparable to other databases. Patients with TS, organic GHD, PWS and CRI seem to be more prone to these side effects.