Final height and pubertal development in 55 children with idiopathic growth hormone deficiency, treated for between 2 and 15 years with human growth hormone

Abstract

Sixty patients with the diagnosis of idiopathic growth hormone deficiency have been followed till final height was reached, after hGH treatment lasting between 2 and 15 (average 5.4) years. Twenty-six had ‘total’ and 13 ‘partial’ isolated growth hormone deficiency (IGHD); 10 had GHD plus gonadotrophin deficiency (GnD); six had multiple pituitary hormone deficiency (MPHD) and five, labelled ‘transient prepubertal GHD’, had normal responses in the insulin tolerance test when retested after the end of treatment.

The final height of the patients with IGHD averaged 2.3 SD below the population mean, or 2.0SD below their midparent mean. Half the boys, but only 15% of the girls, ended above the population 3rd centile. There was no difference in final height between those with ‘total’ and ‘partial’ deficiency nor between patients treated prepubertally and those in whom treatment started in early puberty. In the 39 patients with IGHD the correlation of final height with midparent height was 0.72, a figure identical to that occurring in the normal population. Though final height was chiefly influenced by parental height, it was also affected by the degree of smallness when treatment began being lowered by an average of 2.5 cm for every SD that the patient's height at beginning of treatment lay below the average of all IGHD children, parents' heights being allowed for.

Since untreated patients end at about 6 SD below the mean, treatment during the age span represented in these patients recovered 4SD, but failed to recover the remainder. The lost 2 SD may be due to the late start of treatment (averaging 11 years of age even in our prepubertal patients). Our findings emphasise the importance of early diagnosis, so that future patients never drop to 4 or 5 SD below mean height for age, but only to 2 or 3.

Patients with IGHD plus GnD had final heights averaging 1.5 SD below the population mean and those with MPHD 1.0 SD below. This was entirely due to their developing longer legs than the patients with IGHD, the final sitting heights being the same. The long legs were due to treatment with sex steroids being started relatively late. Patients with IGHD who entered puberty spontaneously did so late in time and in the boys pubertal development was normal. In the girls there was a disturbance in the normal relationship of pubertal events and in two menarche never occurred.