Audran M, Renier J C, Jallet P, Bidet M, Basle M F, Seret P
Rev Rhum Mal Osteoartic. 1987 Feb;54(2):163-9.
1,25 dihydroxyvitamin D (1,25(OH)2 D) is the active metabolite of vitamin D and has an essential role in bony metabolism on the regulation of the calcium-phosphorus balance. The circulating level of 1,2(OH)2 D is normally between 25 and 45 pg/ml. Isolation of the fraction to be titrated requires sophisticated purification techniques using high performance chromatography (HPLC). In osteomalacia secondary to a deficiency the mean level of 1,25(OH)2 D is low (14.1 +/- 6.9 pg/ml) because of substratum deficiency. Administration of vitamin D supplements is quickly followed by a supraphysiological increase of the level of active metabolite. The role of the parathyroid hormone on the activity of 1-hydroxylase is illustrated by the results of the titration in parathyroid dysfunctions: decrease of the mean level in hypoparathyroidism (18 +/- 6.9 pg/ml), and on the contrary, a significant increase in hyperparathyroidism (56.6 +/- 15.4 pg/ml) despite of a spread of the individual values. In 18 cases of idiopathic hypercalciuria, we have only observed an increase of 1,25(OH)2 D level, in two cases. Titration of 1,25(OH)2 D complements the calcium-phosphorus evaluation to precise the physiopathogenic mechanism of the disorders observed in various diseases. Its interpretation requires the joint measurement of the substratum level, 25-hydroxyvitamin D, and the evaluation of the parathyroid function.
1,25-二羟维生素D（1,25(OH)₂D）是维生素D的活性代谢产物，在骨代谢的钙磷平衡调节中起重要作用。1,2(OH)₂D的循环水平通常在25至45 pg/ml之间。分离待滴定的组分需要使用高效液相色谱（HPLC）的复杂纯化技术。在继发于缺乏症的骨软化症中，由于底物缺乏，1,25(OH)₂D的平均水平较低（14.1±6.9 pg/ml）。补充维生素D后，活性代谢产物水平会迅速出现超生理升高。甲状旁腺功能障碍的滴定结果说明了甲状旁腺激素对1-羟化酶活性的作用：甲状旁腺功能减退时平均水平降低（18±6.9 pg/ml），相反，甲状旁腺功能亢进时显著升高（56.6±15.4 pg/ml），尽管个体值存在差异。在18例特发性高钙尿症患者中，我们仅在2例中观察到1,25(OH)₂D水平升高。1,25(OH)₂D的滴定补充了钙磷评估，以明确各种疾病中观察到的疾病的病理生理机制。其解读需要同时测量底物水平、25-羟维生素D，并评估甲状旁腺功能。
