Hamano Takayuki
Osaka University Hospital, Department of Nephrology.
Clin Calcium. 2006 Jun;16(6):987-92.
Serum (S-) or urinary (U-) type I collagen N-telopeptide (NTX) reflect bone resorption by cathepsin K or matrix metalloproteinase (MMP). In our analysis of 18 patients with serum creatinine (S-Cr) less than 2.0 mg/dL, there was a significant positive correlation between S-NTX and U-NTX (U-NTX = 3.7 x S-NTX-13 [r = 0.84, P<0.0001) ] . Because diurnal and day-to-day variations are large in U-NTX assay, it is recommended that U-NTX be measured in the first or second urine of the day. In contrast, physiological variation in S-NTX is relatively small. However, we should bear in mind that S-NTX is interfered with renal function. Before interpretation of S-NTX, we should estimate glomerular filtration rate by using Cockcroft-Gault formula, especially in elderly patients with low body mass index such as rheumatic patients, whose S-Cr-is in normal ranges Both markers are very useful for estimating the risk of bone fracture and for monitoring therapeutic effects of anti-resorptive agents such as bisphosphonate or selective estrogen receptor modulator.
血清（S-）或尿液（U-）I型胶原N-端肽（NTX）反映组织蛋白酶K或基质金属蛋白酶（MMP）引起的骨吸收。在我们对18例血清肌酐（S-Cr）低于2.0mg/dL的患者的分析中，S-NTX与U-NTX之间存在显著正相关（U-NTX = 3.7×S-NTX - 13 [r = 0.84，P<0.0001]）。由于U-NTX检测的日间和每日变化较大，建议在一天中的第一次或第二次尿液中测量U-NTX。相比之下，S-NTX的生理变化相对较小。然而，我们应该记住，S-NTX会受到肾功能的干扰。在解读S-NTX之前，我们应该使用Cockcroft-Gault公式估算肾小球滤过率，尤其是在体重指数较低的老年患者中，如类风湿患者，其S-Cr处于正常范围。这两种标志物对于评估骨折风险和监测抗吸收药物（如双膦酸盐或选择性雌激素受体调节剂）的治疗效果都非常有用。
