Manetti L, Pardini E, Genovesi M, Campomori A, Grasso L, Morselli L L, Lupi I, Pellegrini G, Bartalena L, Bogazzi F, Martino E
Department of Endocrinology, University of Pisa, Ospedale di Cisanello, Italy.
J Endocrinol Invest. 2005 Apr;28(4):346-9. doi: 10.1007/BF03347201.
Cystatin C (Cys C) is a cysteine protease inhibitor produced at a constant rate by nucleated cells, filtered through the glomerular membrane and reabsorbed by kidney tubular cells. Aim of this cross-sectional and longitudinal study was to assess serum Cys C and creatinine (Crea) concentrations in thyroid dysfunction. One hundred and eighty-one patients, 26 with untreated non-toxic nodular goiter, 58 with hyperthyroidism, 31 on L-T4 suppressive therapy for non-toxic nodular goiter, 35 with short-term hypothyroidism after L-T4 withdrawal to perform whole body scan for thyroid cancer, 11 with long-term hypothyroidism due to chronic autoimmune thyroiditis and 20 patients with mild hypothyroidism were enrolled in the study. Fifty-seven age- and sex-matched normal subjects served as controls. Serum Cys C, Crea, free T4 (FT4), FT3 and TSH were assessed. Thirty hyperthyroid patients and 35 short-term hypothyroid patients were followed prospectively until euthyroidism was reached by methimazole or L-T4 therapy. The cross-sectional study showed that mean serum Crea concentrations were significantly reduced in overt hyperthyroid or subclinical hyperthyroid patients, while it was increased in overt hypothyroid patients, but not in mild hypothyroidism. Conversely, serum Cys C levels were significantly increased in overt hyperthyroid patients compared to controls (p<0.05), and significantly decreased in short-term, long-term and mild hypothyroids (p<0.05, p<0.05, p<0.01, respectively). However, 36 (62%) hyperthyroid patients and 50 (76%) hypothyroid patients had normal serum Cys C values. In the prospective study, restoration of euthyroidism by either methimazole or L-T4 therapy was associated with normalization of mean serum Cys C concentrations. In conclusion, thyroid dysfunction affects serum Cys C concentration, possibly influencing the production rate of the protein. However, the observation that hyper- or hypothyroid patients have normal serum Cys C levels limits its use as a marker of peripheral thyroid hormone effect.
胱抑素C（Cys C）是一种由有核细胞以恒定速率产生的半胱氨酸蛋白酶抑制剂，经肾小球膜滤过并被肾小管细胞重吸收。这项横断面和纵向研究的目的是评估甲状腺功能障碍患者的血清Cys C和肌酐（Crea）浓度。181例患者纳入研究，其中26例为未经治疗的非毒性结节性甲状腺肿患者，58例甲状腺功能亢进患者，31例接受L-T4抑制治疗的非毒性结节性甲状腺肿患者，35例在停用L-T4进行甲状腺癌全身扫描后出现短期甲状腺功能减退的患者，11例因慢性自身免疫性甲状腺炎导致长期甲状腺功能减退的患者，以及20例轻度甲状腺功能减退患者。57例年龄和性别匹配的正常受试者作为对照。检测血清Cys C、Crea、游离T4（FT4）、FT3和促甲状腺激素（TSH）。30例甲状腺功能亢进患者和35例短期甲状腺功能减退患者接受前瞻性随访，直至通过甲巯咪唑或L-T4治疗达到甲状腺功能正常。横断面研究表明，显性甲状腺功能亢进或亚临床甲状腺功能亢进患者的平均血清Crea浓度显著降低，而显性甲状腺功能减退患者的平均血清Crea浓度升高，但轻度甲状腺功能减退患者未升高。相反，与对照组相比，显性甲状腺功能亢进患者的血清Cys C水平显著升高（p<0.05），而短期、长期和轻度甲状腺功能减退患者的血清Cys C水平显著降低（分别为p<0.05、p<0.05、p<0.01）。然而，36例（62%）甲状腺功能亢进患者和50例（76%）甲状腺功能减退患者的血清Cys C值正常。在前瞻性研究中，甲巯咪唑或L-T4治疗使甲状腺功能恢复正常与平均血清Cys C浓度正常化相关。总之，甲状腺功能障碍会影响血清Cys C浓度，可能影响该蛋白的产生速率。然而，甲状腺功能亢进或减退患者血清Cys C水平正常这一观察结果限制了其作为外周甲状腺激素作用标志物的应用。
