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To test the hypothesis that hyperlipidemia is characteristic of growth hormone deficiency in childhood, we have measured serum cholesterol and triglyceride concentrations in 24 euthyroid children with growth hormone deficiency. Although modest elevations of cholesterol and/or triglyceride above the 95th percentile for age, race, and sex were present in 46% of the children studied, the mean (+/- 1 SD) cholesterol of 173 +/- 36 mg/dl and the mean triglyceride of 80 +/- 42 mg/dl were not significantly different from published normal mean values. Administration of human growth hormone for 4 mo to 15 of these subjects did not alter these mean cholesterol and triglyceride values, but did result in a marked improvement in the growth rate. Some individuals (n = 6) with a subnormal growth response to therapy and/or a low serum thyroxine and high serum cholesterol were treated for an additional 4 mo with growth hormone and thyroid hormone together. There was a statistically significant decrement in serum cholesterol in this group. We conclude that modest hyperlipidemia does exist in some children with growth hormone deficiency. Subclinical hypothyroidism may play a role in the hypercholesterolemia of some children, as may growth hormone deficiency itself. Any association of growth hormone and lipid metabolism remains to be clarified.

To study the selective effect of thyroid hormone and growth hormone, alone and in combination on plasma cholesterol, 12 children were monitored monthly during three 4-month treatment periods. Plasma cholesterol was unaltered by growth hormone therapy alone (mean +/- SD, basal cholesterol level: 202 +/- 26 mg/dL; cholesterol level after growth hormone 200 +/- 24 mg/dL). With thyroxine (T4) replacement alone, or combined with growth hormone, a significant (P less than 0.01) decrement in plasma cholesterol occurred. (Thyroxine alone: 172 +/- 11 mg/dL; thyroxine and growth hormone: 172 +/- 10 mg/dL). Basal thyroid function tests, including TRH stimulation, were normal. Serum thyroxine levels decreased and serum triiodothyronine (T3) levels increased in response to growth hormone therapy. Linear growth increased significantly in response to growth hormone alone and both therapies combined. Serum values of T4 and T3 were significantly (P less than 0.001) correlated with basal cholesterol, r = 0.84 and r = 0.83, respectively. Our experience with euthyroid growth hormone deficiency confirms that modest hypercholesterolemia is characteristic of that disorder, and that growth hormone therapy has no statistically significant effect on plasma cholesterol. The modest hypercholesterolemia that does respond to thyroid replacement is further evidence of a subtle abnormality of thyroid function in such individuals. The mechanism whereby thyroid hormone has its cholesterol lowering effect in these apparently euthyroid subjects is unclear.