Wan Nazaimoon W M, Khalid B A
Division of Endocrinology, Institute for Medical Research, Kuala Lumpur, Malaysia.
Horm Metab Res. 1998 Apr;30(4):213-6. doi: 10.1055/s-2007-978868.
Thyroid hormones have been shown to be involved in the regulation of insulin-like growth factor-I (IGF-I) and IGF binding protein-3 (IGFBP-3) expression. This is a cross-sectional study to look at the effects of thyroid hormone status on the circulating levels of IGF-I and IGFBP-3 in a group of 127 patients, aged 20-80 years, who were hyperthyroid, hypothyroid, rendered euthyroid and clinically euthyroid with normal free thyroxine (fT4), but suppressed thyroid stimulating hormone (TSH) levels. TSH was measured by the IMx (Abbott) ultrasensitive assay, while radioimmunoassays for total T3 and T4 were performed using kits from ICN, USA; fT4 and fT3 using kits from DPC USA; IGF-I and IGFBP-3 using kits from Nichols Institute Diagnostics B.V., Netherlands. Differences in the levels of IGF-I between the 4 groups of patients were significant only in the patients aged 20-40. Mean (+/-SEM) IGF-I levels of hypothyroid patients (169+/-19ng/ml) was significantly lower than hyperthyroid (315+/-26 ng/ml, p=0.003), euthyroid patients (241+/-19 ng/ml, p=0.002) and patients with suppressed TSH (308+/-29 ng/ml, p=0.02). The IGF-I levels of the hyperthyroid and suppressed TSH patients were, however, comparable to age-matched normal subjects (281+/-86 ng/ml). Although there was no difference in mean IGFBP-3 levels between the 4 groups of patients, the levels in the patients aged 20-40 with hyperthyroidism (3.7+/-0.9 microg/ml) and suppressed TSH (3.9+/-1.2 microg/ml) were significantly higher (p=0.02) than age-matched normal subjects (3.1+/-0.8 microg/ml). The IGF-I levels of the thyroid patients aged 20-40 showed significant negative correlation to TSH and positive correlations to the thyroid hormones. Hence, whilst low IGF-I is associated with hypothyroidism, high IGFBP-3 is associated with hyperthyroidism. Our finding that IGFBP-3 remained significantly elevated in patients with suppressed TSH but normalised fT4 and fT3 is important as it suggests a prolonged tissue effect of thyroid hormones on IFGBP-3. As such patients have been shown to have higher risk for atrial fibrillation, the significance and possible role of IGFBP-3 in these conditions should be further elucidated in future studies.
甲状腺激素已被证明参与胰岛素样生长因子-I（IGF-I）和IGF结合蛋白-3（IGFBP-3）表达的调节。这是一项横断面研究，旨在观察甲状腺激素状态对一组127例年龄在20至80岁之间的患者循环中IGF-I和IGFBP-3水平的影响，这些患者分别为甲状腺功能亢进、甲状腺功能减退、甲状腺功能正常以及临床甲状腺功能正常但促甲状腺激素（TSH）水平被抑制且游离甲状腺素（fT4）正常。TSH通过IMx（雅培）超敏测定法测量，总T3和T4的放射免疫测定使用美国ICN公司的试剂盒；fT4和fT3使用美国DPC公司的试剂盒；IGF-I和IGFBP-3使用荷兰尼科尔斯研究所诊断公司的试剂盒。4组患者中IGF-I水平的差异仅在20至40岁的患者中具有统计学意义。甲状腺功能减退患者的平均（±标准误）IGF-I水平（169±19ng/ml）显著低于甲状腺功能亢进患者（315±26 ng/ml，p = 0.003）、甲状腺功能正常患者（241±19 ng/ml，p = 0.002）以及TSH被抑制的患者（308±29 ng/ml，p = 0.02）。然而，甲状腺功能亢进和TSH被抑制患者的IGF-I水平与年龄匹配的正常受试者（281±86 ng/ml）相当。尽管4组患者的平均IGFBP-3水平没有差异，但20至40岁甲状腺功能亢进患者（3.7±0.9μg/ml）和TSH被抑制患者（3.9±1.2μg/ml）的水平显著高于年龄匹配的正常受试者（3.1±0.8μg/ml，p = 0.02）。20至40岁甲状腺疾病患者的IGF-I水平与TSH呈显著负相关，与甲状腺激素呈正相关。因此，虽然低IGF-I与甲状腺功能减退有关，但高IGFBP-3与甲状腺功能亢进有关。我们的发现，即TSH被抑制但fT4和fT3正常的患者中IGFBP-3仍显著升高，这一点很重要，因为它提示了甲状腺激素对IFGBP-3的长期组织效应。由于这类患者已被证明患心房颤动的风险较高，IGFBP-3在这些情况下的意义和可能作用应在未来的研究中进一步阐明。
