Background: The anabolic properties of human growth hormone (HGH) may prove beneficial in critically ill surgical patients. Potential effects of hypercalcemia with HGH therapy have not been addressed for adult patients in the intensive care unit.
Methods: We performed a retrospective review of the past 100 patients treated with HGH in a surgical intensive care unit. Laboratory data, including serum calcium levels, were recorded at baseline and during HGH therapy. Additionally, calcium levels in 27 burn patients receiving HGH were compared with calcium levels in a well-matched group of 27 burn patients not receiving HGH. The incidence and severity of hypercalcemia were recorded, with attention to contributing factors and overall outcome.
Results: There was a statistically significant increase in the mean +/- SD serum calcium level with the institution of HGH therapy (2.50 +/- 0.20 mmol/L [10.0 +/- 0.8 mg/dL] before HGH vs 2.74 +/- 0.27 mmol/L [11.0 +/- 1.1 mg/dL] during HGH, P < .05). Before HGH, 14% of the patients had hypercalcemia, defined as a calcium level greater than 2.74 mmol/L (11.0 mg/dL). During HGH, 43% of the patients developed hypercalcemia. Before HGH, no patient exhibited severe hypercalcemia, defined as a calcium level greater than 3.12 mmol/L (12.5 mg/dL). However, during HGH, 10% of the patients developed severe hypercalcemia. Elevations in serum calcium levels were correlated with the duration of HGH therapy and renal dysfunction. Burn patients receiving HGH exhibited significantly higher mean +/- SD calcium levels than controls (2.87 +/- 0.32 mmol/L [11.5 +/- 1.3 mg/dL] vs 2.50 +/- 0.17 mmol/L [10.0 +/- 0.7 mg/dL], P < .001). Studies performed in selected patients demonstrated that alterations in parathyroid function, vitamin D metabolism, and thyroid function did not appear to contribute to this effect.
Conclusion: Prolonged HGH therapy in critically ill surgical patients may result in severe hypercalcemia, particularly in patients with altered renal function. Possible mechanisms for HGH-induced hypercalcemia include increased intestinal absorption and decreased urinary excretion. Outcome was not adversely affected by this biochemical alteration, but careful monitoring of calcium levels should be undertaken in this population receiving HGH.