Department of Medical Biochemistry, Vestfold Hospital Trust, Tønsberg, Norway.
Department of Medical Biochemistry, Oslo University Hospital - Radiumhospitalet, Oslo, Norway.
Clin Chem Lab Med. 2020 Oct 30;59(4):663-669. doi: 10.1515/cclm-2020-1411. Print 2021 Mar 26.
Monoclonal immunoglobulins can cause interference in many laboratory analyses. During a 4 month period we observed seven patients with monoclonal disease and falsely extremely elevated 25-hydroxyvitamin D (25(OH)D) results above 160 ng/mL (>400 nmol/L) measured using an immunoassay from Abbott Diagnostics. Based on these findings, we studied the occurrence of falsely elevated 25(OH)D in samples with paraproteins and investigated possible mechanisms of the observed interference.
25(OH)D was analyzed using the Architect i2000 platform from Abbott Diagnostics and a higher order method, liquid chromatography-mass spectrometry (LC-MS/MS), in serum samples from 50 patients with known monoclonal disease. Patients with falsely elevated 25(OH)D were included in further studies to elucidate the cause of interference. Spuriously elevated results were in addition analyzed on two alternative platforms (Siemens and Roche).
Falsely elevated 25(OH)D levels were present in eight patients on the Abbott analyzer and one on the Siemens platform. Results from Roche were comparable with LC-MS/MS. Additional investigations excluded elevated concentrations of rheumatoid factor and heterophilic antibodies as the cause of interference in the Abbott assay.
Laboratories should be aware of the risk of falsely elevated 25(OH)D in samples run on the Architect analyzer from patients with monoclonal disease. Highly elevated vitamin D results should be diluted and if the dilution is non-linear, rerun by a different method, preferably LC-MS/MS. In patients with spuriously elevated 25(OH)D without known monoclonal disease, the laboratory should consider requesting protein electrophoresis to exclude paraprotein interference.
单克隆免疫球蛋白可对许多实验室分析造成干扰。在 4 个月期间，我们观察到 7 例单克隆疾病患者，其 25-羟维生素 D（25(OH)D）结果使用 Abbott Diagnostics 的免疫分析法检测，结果极度升高至 160ng/mL 以上（>400nmol/L）。基于这些发现，我们研究了在存在副蛋白的样本中出现假性升高的 25(OH)D 的情况，并探讨了观察到的干扰的可能机制。
使用 Abbott Diagnostics 的 Architect i2000 平台和液相色谱-质谱联用（LC-MS/MS）对 50 例已知单克隆疾病患者的血清样本进行 25(OH)D 分析。将假性升高 25(OH)D 的患者纳入进一步研究，以阐明干扰的原因。此外，在两个替代平台（Siemens 和 Roche）上分析了假性升高的结果。
在 Abbott 分析仪上有 8 例患者和 Siemens 平台上有 1 例患者存在假性升高的 25(OH)D 水平。罗氏的结果与 LC-MS/MS 相媲美。进一步的调查排除了类风湿因子和异嗜性抗体的升高浓度是 Abbott 测定干扰的原因。
实验室应意识到单克隆疾病患者的样本在 Architect 分析仪上运行时，25(OH)D 可能出现假性升高的风险。对于高度升高的维生素 D 结果，应进行稀释，如果稀释非线性，应使用另一种方法（最好是 LC-MS/MS）重新检测。对于没有已知单克隆疾病的患者，如果出现 25(OH)D 假性升高，实验室应考虑要求进行蛋白电泳以排除副蛋白干扰。
