Musolino N R, Da Cunha Neto M B, Marino Júnior R, Giannella-Neto D, Bronstein M D
Unidade de Neuroendocrinologia, Hospital das Clinicas, São Paulo, Brazil.
Clin Endocrinol (Oxf). 1999 Apr;50(4):441-9. doi: 10.1046/j.1365-2265.1999.00677.x.
Insulin-like growth factor (IGF-I) and IGF binding protein-3 (IGFBP-3) are GH-dependent and their concentrations have been used in the diagnosis of GH deficiency. Recently, the free fraction of IGF-I has received more attention. The aim of the study was to assess the role of free IGF-I in the diagnosis of GH deficiency in adults, and in follow-up during treatment with recombinant human GH (rhGH).
We studied 24 adult patients with pituitary disease and GH deficiency and 25 matched controls. Nine patients were re-evaluated after 6 months of treatment with rhGH (0.25 U/kg/week).
Serum levels of IGF-I, free IGF-I, IGFBP-3 and IGFBP-1 were measured by immunoradiometric assay.
Serum free IGF-I levels were significantly lower in the GH deficient group than in the normal group (mean: 0.84 and 1.32 micrograms/l respectively, P = 0.0009). Furthermore, serum IGF-I levels were also lower (mean: 92.24 and 230.47 micrograms/l respectively, P < 0.0001). 63% of patients had serum IGF-I concentration below the normal range. For free IGF-I, 52% of the GH deficient patients showed levels below the lowest value obtained for the normal group. Seventy-five percent of the patients showed at least one of the two determinations below the normal range. The free-total IGF-I ratio was significantly higher (P = 0.025) in GH deficient group (range: 0.19-21.29, mean: 2.53) than in normal controls (range: 0.2-2.15, mean: 0.6). Regarding IGFBP-3 and IGFBP-1 no differences were observed between the two groups. During rhGH treatment the increase in serum total and free IGF-I and IGFBP-3 paralleled the beneficial effects on body composition.
Free IGF-I may be another useful method for the diagnosis of GH deficiency, particularly if related to total IGF-I concentration.
胰岛素样生长因子（IGF-I）和IGF结合蛋白-3（IGFBP-3）受生长激素（GH）调控，其浓度已用于诊断GH缺乏症。近来，游离IGF-I受到更多关注。本研究旨在评估游离IGF-I在成人GH缺乏症诊断及重组人生长激素（rhGH）治疗随访中的作用。
我们研究了24例患有垂体疾病且存在GH缺乏症的成年患者以及25例匹配的对照者。9例患者在接受rhGH（0.25U/kg/周）治疗6个月后进行了重新评估。
采用免疫放射分析法测定血清IGF-I、游离IGF-I、IGFBP-3和IGFBP-1水平。
GH缺乏组血清游离IGF-I水平显著低于正常组（均值分别为0.84和1.32μg/L，P = 0.0009）。此外，血清IGF-I水平亦较低（均值分别为92.24和230.47μg/L，P < 0.0001）。63%的患者血清IGF-I浓度低于正常范围。就游离IGF-I而言，52%的GH缺乏患者水平低于正常组最低值。75%的患者两项测定中至少有一项低于正常范围。GH缺乏组游离-总IGF-I比值显著高于正常对照组（P = 0.025）（范围：0.19 - 21.29，均值：2.53），正常对照组范围为0.2 - 2.15，均值为0.6。两组间IGFBP-3和IGFBP-1未观察到差异。rhGH治疗期间，血清总IGF-I、游离IGF-I和IGFBP-3的升高与对身体成分的有益作用平行。
游离IGF-I可能是诊断GH缺乏症的另一种有用方法，尤其是与总IGF-I浓度相关时。
