[Growth hormone treatment of familial hypophosphatemic rickets]

Recombinant growth hormone therapy for X-linked hypophosphatemia in children

BACKGROUND

Conventional treatment of X-linked hypophosphatemia with oral phosphate and calcitriol can heal rickets, but it does not always raise serum phosphate concentrations significantly, nor does it always normalize linear growth. Some clinical trials suggest that combining recombinant human growth hormone therapy with conventional treatment improves growth velocity, phosphate retention, and bone mineral density, but some clinical trials suggest that it appears to aggravate the pre-existent disproportionate stature of such children. This is an updated version of a previously published review.

OBJECTIVES

To determine whether recombinant human growth hormone therapy for children with X-linked hypophosphatemia is associated with changes in longitudinal growth, mineral metabolism, endocrine function, renal function, bone mineral density, body proportions, and also with any adverse effects.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register which comprises references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings. In addition, we searched the Cochrane Central Register of Controlled Trials, Ovid MEDLINE and the reference lists of identified trials and other reviews. We also undertook some additional handsearching of relevant journals and conference proceedings. Date of the most recent search: 12 January 2021 SELECTION CRITERIA: All randomized controlled studies or quasi-randomized controlled studies comparing growth hormone (alone or combined with conventional treatment) with either placebo or conventional treatment alone in children with X-linked hypophosphatemia.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed studies for risk of bias and extracted data from eligible studies. GRADE criteria were used to assess the certainty of the evidence for each outcome.

MAIN RESULTS

We included two studies (20 participants) in the review. In one cross-over study, results showed that recombinant human growth hormone therapy may improve the height standard deviation (SDS) score (z score), but we are unsure whether the intervention was the reason behind a transient increase in serum phosphate and tubular maximum for phosphate reabsorption. In the second, parallel study, treatment may also have improved the height SDS from baseline in the rhGH group compared to the control group, although no significant difference was seen between groups after three years, MD 0.50 SDS (95 % CI -0.54 to 1.54) (low-certainty evidence). The treatment was possibly well-tolerated during both studies with only transient adverse effects seen in three participants (low-certainty evidence). We are uncertain whether growth hormone improves serum phosphate levels or change in TmP/GFR (very low-certainty evidence). The treatment may make little or no difference to alkaline phosphatase levels (low-certainty evidence).

AUTHORS' CONCLUSIONS

We do not have enough high-certainty evidence to recommend the use of recombinant human growth hormone therapy in children with X-linked hypophosphatemia.

X-linked vitamin D-resistant rickets: 12 years of follow-up

Rickets are abnormalities of mineralization that can lead to bone fractures and deformities. Vitamin-resistant rickets is defined as any rickets not prevented by regular, early and prolonged administration of vitamin D and not cured by a sufficient total dose. The aim of our work is to describe the clinical, paraclinical and therapeutic aspects of X-linked hypophosphatemic rickets (XLHR), which is the most common cause of hereditary rickets and on the other hand to highlight the interest not only of the early care but also the regular long-term monitoring of these children.

Growth and growth hormone treatment in children with chronic diseases

Growth hormone has been available for treatment of various conditions for over 50 years. There have been a number of chronic disease states in which it has been used, such as chronic kidney disease, which became a US Food and Drug Administration (FDA)-approved indication in 1993. For other chronic disease states there have been clinical studies supporting its use, but they have not yet been approved as a indications by the FDA. Examples of such diseases are cystic fibrosis, chronic arthritis, short bowel syndrome, burn trauma, and hypophosphatemic rickets.

Emerging options in growth hormone therapy: an update

Growth hormone (GH) was first used to treat a patient in 1958. For the next 25 years it was available only from cadaver sources, which was of concern because of safety considerations and short supply. In 1985, GH produced by recombinant DNA techniques became available, expanding its possible uses. Since that time there have been three indications approved by the US Food and Drug Administration (FDA) for GH-deficiency states and nine indications approved for non-GH-deficiency states. In 2003 the FDA approved GH for use in idiopathic short stature (ISS), which may indirectly cover other diagnoses that have short stature as a feature. However, coverage for GH therapy is usually more reliably obtainable for a specific indication, rather than the ISS indication. Possible future uses for GH therapy could include the treatment of syndromes such as Russell-Silver syndrome or chondrodystrophy. Other non-short-stature indications could include wound healing and burns. Other uses that have been poorly studied include aging and physical performance, in spite of the interest already shown by elite athletes in using GH. The safety profile of GH developed over the past 25 years has shown it to be a very safe hormone with few adverse events associated with it. The challenge for the future is to follow these patients into adulthood to determine whether GH therapy poses any long-term risks.

Recombinant growth hormone therapy for X-linked hypophosphatemia in children

BACKGROUND

Conventional treatment of X-linked hypophosphatemia with oral phosphate and calcitriol can heal rickets, but it does not always raise serum phosphate concentrations significantly, nor does it always normalize linear growth. Some clinical trials suggest that combining recombinant human growth hormone therapy with conventional treatment improves growth velocity, phosphate retention, and bone mineral density, but some clinical trials suggest that it appears to aggravate the pre-existent disproportionate stature of such children.

OBJECTIVES

To determine whether recombinant human growth hormone therapy for children with X-linked hypophosphatemia is associated with changes in longitudinal growth, mineral metabolism, endocrine function, renal function, bone mineral density, body proportions, and also with any adverse effects.

SEARCH STRATEGY

Relevant trials were identified from searching the Cochrane Central Register of Controlled Trials Issue 3, 2003 and Ovid MEDLINE 1966 to September 2003. Additional trials were identified from the reference lists of identified trials and other reviews. We also searched the Journal of Bone and Mineral Research (1986 to 2003) and proceedings of the American Society for Bone and Mineral Research Annual Meeting (1st to 24th). Date of most recent search: November 2003.

SELECTION CRITERIA

All randomized controlled trials or quasi-randomized controlled trials comparing growth hormone (alone or combined with conventional treatment) with either placebo or conventional treatment alone in children with X-linked hypophosphatemia.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed trials for methodological quality and extracted data from eligible trials.

MAIN RESULTS

The searches identified five trials, of which one met the inclusion criteria, including a total of five participants. In this trial, rhGH therapy improved the height standard deviation score (z score), and transiently increased serum phosphate and tubular maximum for phosphate reabsorption.

AUTHORS' CONCLUSIONS

We have found no conclusive evidence to indicate that the use of recombinant human growth hormone therapy in children with XLH is associated with changes in longitudinal growth, mineral metabolism, endocrine, renal function, bone mineral density, body proportions, but it does not appear to have any adverse effects.