Blood pressure and the renin-angiotensin-aldosterone system in children receiving recombinant human growth hormone.

OBJECTIVE

We investigated the effect of growth hormone (GH) treatment on salt and water metabolism and the renin-angiotensin-aldosterone system in children with short stature.

DESIGN

Randomized, controlled study.

PATIENTS

Twenty-nine short, pre-pubertal children referred to two specialist growth clinics for further assessment.

MEASUREMENTS

Serial measurements of blood pressure, body weight, plasma renin activity (PRA), aldosterone, electrolytes, insulin and insulin-like growth factor I (IGF-I) have been made following the initiation of GH treatment.

RESULTS

A small and transient increase in systolic blood pressure was observed during the first week of GH treatment. The increase in blood pressure over baseline was -1.1 mmHg in controls compared to +11.5 and +3.0 mmHg in children receiving standard (20 units/m2/week) and high dose (40 units/m2/week) GH respectively (P = 0.004). Over the same time interval body weight also tended to increase with GH compared with controls. These changes were greater in those children receiving the lower dose of GH and were not significantly related to age or prior GH status. PRA did not change with GH treatment. Although plasma aldosterone concentration tended to increase with GH, maximal values did not differ from controls and all remained within our normal range. Plasma IgF-I levels were increased by a similar amount in both treatment groups (1.5 and 1.12 U/ml compared to 0.44 U/ml in controls at 4 months). No difference in plasma insulin concentration was noted after 7 days of GH.

CONCLUSIONS

In contrast to adult subjects, treatment with high dose GH in childhood is not associated with activation of the renin-angiotensin-aldosterone system. Clinical signs consistent with transient salt and water retention are observed with GH therapy, however, suggesting either a direct effect of GH or of IGF-I on renal tubular function. Blood pressure, plasma renin activity and plasma aldosterone levels were not increased after more prolonged GH therapy. These data suggest that high dose GH therapy in childhood is unlikely to be associated with the increased risk of hypertension seen in adults with GH hypersecretion.