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Water and sodium retention during short-term administration of growth hormone to short normal children
1Department of Pediatrics, Rambam Medical Center, Haifa, Israel.
Insights
Growth hormone (GH) therapy in short children causes temporary sodium and water retention, linked to increased plasma renin activity (PRA). These effects normalize within weeks, indicating transient hormonal changes during early treatment.
Area of Science:
- Pediatrics
- Endocrinology
- Nephrology
Background:
- Growth hormone (GH) administration in adults with GH deficiency (GHD) or healthy individuals is known to cause weight gain and fluid/sodium retention.
- The effects of GH on water and electrolyte balance in healthy short children are less understood.
Purpose of the Study:
- To investigate the impact of short-term recombinant human GH (rhGH) administration on water and sodium homeostasis in short, normal children.
- To evaluate changes in plasma renin activity (PRA) and aldosterone levels during rhGH therapy.
Main Methods:
- Eleven prepubertal short normal children received daily rhGH (2.5 units/m2) for 4 weeks.
- Dehydration and water load tests were performed before GH and on days 3, 7, and 28 of treatment.
- Evaluated parameters included urinary volume, fractional excretion of sodium and potassium, plasma renin activity (PRA), and aldosterone.
Main Results:
- After 3 days of rhGH, children showed significant water retention (excreting less of the water load) and decreased fractional excretion of sodium and potassium.
- Plasma renin activity (PRA) and serum aldosterone levels increased significantly by day 3.
- These changes in water and sodium balance, along with hormonal alterations, normalized by days 7 and 28 of rhGH therapy.
Conclusions:
- Short-term rhGH administration in short normal children induces a transient, mild sodium and secondary water retention.
- The early phase of rhGH therapy is associated with an increase in PRA, suggesting it's a primary factor in sodium retention.
- These hormonal and fluid balance changes are temporary and resolve with continued rhGH treatment.
Abstract:
GH treatment of adult patients with GH deficiency (GHD) or healthy volunteers results in weight gain and fluid and sodium retention. In the present study we have challenged normal short children with dehydration and water load, and evaluated their water and sodium clearance, plasma renin activity (PRA) and aldosterone over 4 weeks of GH administration. Eleven prepubertal short normal children, aged 4-9 years, were the subjects of this study. Recombinant GH was administered daily at a dose of 2.5 units/m2. Dehydration and water load experiments were conducted before GH (day 0) and on days 3, 7 or 28 of GH. An initial 15-hour fast ended with a 3-hour urine collection. A tap-water load of 800 ml/m2 was given orally. Urinary volumes were followed hourly for 3 h, as were urinary and serum creatinine, Na, K, aldosterone, plasma osmolality and PRA. Before GH therapy the subjects excreted within 2 h a mean 42% and within 3 h a mean 65% of the load. After 3 days of GH therapy the same children retained water significantly and excreted only 22 (p < 0.02) and 45% (p < 0.05) of the load volume, respectively. Calculating the free water clearance revealed no effect of GH therapy, whereas the fractional excretion of sodium and potassium decreased significantly by day 3 of GH administration, along with an increase in PRA and serum aldosterone. All these changes normalized by days 7 and 28 of GH therapy. It is concluded that short-term administration of GH to short normal children results in a transitory mild retention of sodium and a secondary water retention, and suggests that the primary event leading to sodium retention during the early phase of GH therapy of short normal children is an inappropriate increase in PRA.