Ong Michal Ws, Salota Rashim, Reeman Tracy, Lapsley Marta, Jones Lydia
1 Department of Haematology, Epsom and St Helier University Hospitals NHS Trust, Carshalton, Surrey, UK.
2 Department of Chemical Pathology, Epsom and St Helier University Hospitals NHS Trust, Carshalton, Surrey, UK.
Ann Clin Biochem. 2017 Nov;54(6):716-720. doi: 10.1177/0004563217690175. Epub 2017 Mar 16.
The most commonly used techniques to measure vitamin D are automated immunoassays which are known to be affected by interferences, especially from immunoglobulins present in the patient's serum. We present a case of a patient with myeloma in whom interference with the vitamin D assay was identified. An 83-year-old female, known to have IgG myeloma, was found to have a high concentration of 25-OH vitamin D on a routine test without any signs of vitamin D toxicity. She was not taking vitamin D supplements or any other multivitamin preparation and had minimal sun exposure. The initial and subsequent samples run by the ARCHITECT 25-OH vitamin D assay (chemiluminescent microparticle immunoassay technology, Abbott Laboratories, Abbott Park, IL) showed a high concentration of 25-OH vitamin D of 281 nmol/L and 327 nmol/L, respectively. Further fresh samples taken for 25-OH vitamin D and analysed by liquid chromatography-mass spectrometry (LC-MS/MS) and ARCHITECT analysis showed results of 49 nmol/L and 289 nmol/L, respectively. Our patient had high concentrations of circulating IgG paraproteins and had a long history of rheumatoid arthritis; paraproteins and rheumatoid factor may interfere in the assay. In conclusion, we report a case of a patient with IgG myeloma and rheumatoid arthritis with high concentrations of 25-OH vitamin D detected by the Abbott ARCHITECT, but not by a reference method (LC-MS/MS). The most likely cause of the discordant results is interference in the immunoassay by the paraprotein but interference from rheumatoid factor remains a possibility.
测量维生素D最常用的技术是自动化免疫测定法，已知该方法会受到干扰的影响，尤其是患者血清中存在的免疫球蛋白的干扰。我们报告了一例骨髓瘤患者，其中发现了对维生素D测定的干扰。一名83岁的女性，已知患有IgG骨髓瘤，在常规检查中发现25-羟基维生素D浓度很高，但没有任何维生素D中毒的迹象。她没有服用维生素D补充剂或任何其他多种维生素制剂，且极少晒太阳。采用ARCHITECT 25-羟基维生素D测定法（化学发光微粒免疫测定技术，雅培实验室，伊利诺伊州雅培公园）检测的初始样本和后续样本显示，25-羟基维生素D的浓度分别很高，为281nmol/L和327nmol/L。进一步采集的用于检测25-羟基维生素D的新鲜样本，经液相色谱-质谱联用仪（LC-MS/MS）分析和ARCHITECT分析，结果分别为49nmol/L和289nmol/L。我们的患者循环IgG副蛋白浓度很高，且有类风湿性关节炎的长期病史；副蛋白和类风湿因子可能会干扰检测。总之，我们报告了一例IgG骨髓瘤和类风湿性关节炎患者，雅培ARCHITECT检测到其25-羟基维生素D浓度很高，但参考方法（LC-MS/MS）未检测到。结果不一致的最可能原因是副蛋白对免疫测定的干扰，但类风湿因子的干扰仍有可能。
