Gøransson Lasse G, Skadberg Øyvind, Bergrem Harald
Stavanger University Hospital, PO Box 8100, 4068 Stavanger, Norway.
Nephrol Dial Transplant. 2005 Oct;20(10):2126-9. doi: 10.1093/ndt/gfh988. Epub 2005 Jul 19.
Secondary hyperparathyroidsm is frequently observed in patients with chronic renal failure, and clinical treatment guidelines have been published. Despite this, a large proportion of patients do not reach the target levels for calcium, phosphorus, calcium x phosphorus product, or intact parathyroid hormone. The use of albumin-corrected calcium is recommended as calcium measurement, but it is the concentration of ionized calcium that is biologically active. We hypothesized that in clinical practice, the use of ionized calcium rather than albumin-corrected calcium would influence the calcium classification of the individual patient.
Blood samples from 34 patients in chronic haemodialysis were analysed for evaluation of mineral metabolism according to K/DOQI guidelines. Blood for analysis of total and ionized calcium was drawn simultaneously. As ionized calcium is pH dependent, samples were analysed at the actual pH of the individual patient.
For both methods, a similar number of patients were characterized as normocalcaemic. The use of albumin-corrected calcium caused one patient (3%) to be classified as hypocalcaemic, and 10 patients (26%) as hypercalcaemic whereas with ionized calcium, five (15%) and three patients (9%) were classified as hypo- and hypercalcaemic, respectively.
According to present guidelines, the difference in calcium classification of patients might have clinical implications for the prescription of vitamin D, and on the choice of phosphate binders.
继发性甲状旁腺功能亢进在慢性肾衰竭患者中很常见，并且已经发布了临床治疗指南。尽管如此，仍有很大一部分患者的钙、磷、钙磷乘积或完整甲状旁腺激素未达到目标水平。推荐使用白蛋白校正钙作为钙测量指标，但具有生物活性的是离子钙浓度。我们推测在临床实践中，使用离子钙而非白蛋白校正钙会影响个体患者的钙分类。
根据K/DOQI指南，对34例慢性血液透析患者的血样进行分析以评估矿物质代谢。同时采集用于分析总钙和离子钙的血液。由于离子钙依赖于pH值，样本在个体患者的实际pH值下进行分析。
对于两种方法，被归类为血钙正常的患者数量相似。使用白蛋白校正钙导致1例患者（3%）被归类为低钙血症，10例患者（26%）被归类为高钙血症；而使用离子钙时，分别有5例（15%）和3例（9%）患者被归类为低钙血症和高钙血症。
根据目前的指南，患者钙分类的差异可能对维生素D的处方以及磷结合剂的选择具有临床意义。
