Endocrine Abstracts

Introduction

Growth hormone deficiency (GHD) is a rare disorder and severe forms of GHD may have a genetic basis. Familial isolated growth hormone deficiency (IGHD) is classified into 4 types, type IA being the most severe form. These patients present with severe growth failure with undetectable growth hormone (GH) concentrations and about 50% tend to develop antibodies on GH treatment.(1, 2, 3) The appearance of anti-GH antibodies may not be a regular finding even among members of the same family. There have been reported cases when these antibodies have disappeared after a few years. (4, 5).

Case report

We present the case of a young female patient who was referred for endocrinological evaluation for short stature at the age of 1 year. She came from a family with a very short mother (height of 145 cm) without an endocrinological evaluation and a sister treated with somatropinum for severe GHD for 9 years, with a good height response to treatment. The patient presented with severe short stature, height of 62 cm (–5.17 standard deviations, SD), with normal weight (body mass index (BMI) 16.64 kg/m²). The paraclinical exam showed undetectable GH, low values of insulin growth factor 1 (IGF1), normal 25 hydroxyvitamin (25OHD), normal thyroid and adrenal function. Dynamic growth hormone evaluation showed unstimulated levels. Pituitary MRI (magnetic resonance imaging) showed adenohypophyseal hypoplasia. Based on the evaluation she was diagnosed with severe GHD and received treatment with somatropinum 0.23 microg/kg bw/day. At the six months reevaluation we found a height of 63.3 cm (–6.11 SD) and a BMI of 15.62 kg/m². The response to treatment was considered inadequate and an IGF1 generation test was performed without a significant increase of IGF1. The most probable explanation was the presence of GH antibodies, but the test was not available. She was followed for 1 year, but the height parameters were not improved (at the age of 2.5 years, height of 64.8 cm, -6.94 SD)

Conclusions

In patients with familial IGHD the response to somatropinum treatment could be affected by the appearance of anti-GH antibodies. Although these antibodies can disappear after few years, in cases with disabilitating short stature the lack of treatment can have a severe impact on the well being and the development of the patients. Although mecasermin might be an alternative in these cases, their approved indications can limit the access to treatment.