Insogna K L, Broadus A E, Dreyer B E, Ellison A F, Gertner J M
J Clin Endocrinol Metab. 1985 Sep;61(3):490-5. doi: 10.1210/jcem-61-3-490.
Previous studies of 1,25-dihydroxyvitamin D [1,25-(OH)2D] kinetics in normal subjects using the pulse injection technique have led to conflicting results, and only limited data are available concerning 1,25-(OH)2D kinetics in hypercalciuric patients. We developed an infusion equilibrium technique that measures the metabolic clearance and production rates of 1,25-(OH)2D and applied this technique in 13 normal subjects and 9 well characterized patients with absorptive hypercalciuria; all subjects were studied after 10 days on a 400-mg calcium intake. All subjects received a constant infusion of [3H]1,25-(OH)2D3 (20,000 dpm/min). Purified plasma radioactivity reached steady state levels after 15 h, and between 15 and 19 h, serial measurements of purified plasma radioactivity and endogenous 1,25-(OH)2D were made for calculation of metabolic clearance and production rates. In the 13 normal subjects, the MCR values were within a narrow range, with a mean +/- SD value of 37 +/- 6 ml/min, which, when combined with the mean steady state concentration of endogenous 1,25-(OH)2D (42 +/- 6 pg/ml), yielded a mean production rate of 2.2 +/- 0.5 micrograms/day. In the 9 patients with absorptive hypercalciuria, MCR values also were tightly clustered, with a mean of 35 +/- 4 ml/min. However, the mean endogenous steady state 1,25-(OH)2D level was significantly elevated in these patients, such that the calculated mean 1,25-(OH)2D production rate was significantly elevated at 3.4 +/- 0.5 micrograms/day. In 7 of the 9 patients with absorptive hypercalciuria, production rates exceeded the highest values found in the normal subjects. These data demonstrate disordered 1,25-(OH)2D production as opposed to metabolic clearance in the syndrome of absorptive hypercalciuria.
以往利用脉冲注射技术对正常受试者1,25 - 二羟维生素D [1,25-(OH)₂D]动力学进行的研究结果相互矛盾，而关于高钙尿症患者1,25-(OH)₂D动力学的数据有限。我们开发了一种输注平衡技术，用于测量1,25-(OH)₂D的代谢清除率和生成率，并将该技术应用于13名正常受试者和9名特征明确的吸收性高钙尿症患者；所有受试者在摄入400毫克钙10天后接受研究。所有受试者均接受[³H]1,25-(OH)₂D₃的持续输注（20,000 dpm/分钟）。纯化血浆放射性在15小时后达到稳态水平，并在15至19小时之间，对纯化血浆放射性和内源性1,25-(OH)₂D进行连续测量，以计算代谢清除率和生成率。在13名正常受试者中，MCR值在狭窄范围内，平均±标准差为37±6毫升/分钟，与内源性1,25-(OH)₂D的平均稳态浓度（42±6皮克/毫升）相结合，得出平均生成率为2.2±0.5微克/天。在9名吸收性高钙尿症患者中，MCR值也紧密聚集，平均为35±4毫升/分钟。然而，这些患者的内源性稳态1,25-(OH)₂D水平显著升高，因此计算得出的平均1,25-(OH)₂D生成率显著升高，为3.4±0.5微克/天。在9名吸收性高钙尿症患者中的7名患者中，生成率超过了正常受试者中的最高值。这些数据表明，在吸收性高钙尿症综合征中，与代谢清除相反，1,25-(OH)₂D生成紊乱。
