Delgado José A, Pastor María I, Costa Gemma, Márquez Nuria, Bauça Josep Miquel
Department of Laboratory Medicine, Hospital Universitari Son Espases, Palma, Spain.
Institut d'Investigació Sanitària de les Illes Balears, Palma de Mallorca, Spain.
Adv Lab Med. 2024 Jul 12;5(4):386-393. doi: 10.1515/almed-2024-0041. eCollection 2024 Dec.
The presence of macro-B12 is a cause of factual hypervitaminemia B12. Precipitation with polyethylene glycol (PEG) is a simple method of removing high-molecular-weight biomolecules. However, "free" molecule may co-precipitate. This fact requires the establishment of reference intervals for the post-precipitation result. The main aims of the study were to: 1) establish post-PEG RIs for vitamin B12; 2) compare the two criteria for defining the presence of macro-B12; 3) evaluate the joint usefulness of percentage post-PEG vitamin B12 recovery and post-PEG RIs to inform the real vitamin B12 status; and 4), propose interpretative comments for ease of interpretation.
Prospective study in which 488 serum samples from "healthy" individuals were included and analyzed to determine recovery and RIs following PEG precipitation. Subsequently, a retrospective analysis was carried out in order to evaluate the joint usefulness of both definitions for a suspicion of macro-B12. A total of 297 cases were included.
Recovery and post-PEG RIs determined on an Alinity i platform ranged from 60 to 107 % and from 118 to 506 pmol/L, respectively. McNemar's test revealed statistically significant differences between both criteria for estimating interference. However, both methodologies showed good agreement. In 27 cases, the presence of macro-B12 coexisted with true hypervitaminemia B12. No case of coexistence of macro-B12 with vitamin B12 deficiency was detected in our series.
Laboratory reports should include total vitamin B12 concentration, recovery and post-PEG vitamin B12 concentration with their adjusted RIs to better assess the body vitamin status.
巨维生素B12的存在是导致实际维生素B12血症的原因。用聚乙二醇（PEG）沉淀是去除高分子量生物分子的一种简单方法。然而，“游离”分子可能会共沉淀。这一事实需要为沉淀后结果建立参考区间。本研究的主要目的是：1）建立维生素B12的PEG沉淀后参考区间；2）比较定义巨维生素B12存在的两种标准；3）评估PEG沉淀后维生素B12回收率和PEG沉淀后参考区间对了解实际维生素B12状态的联合效用；4）提出便于解读的解释性意见。
进行前瞻性研究，纳入488份来自“健康”个体的血清样本，分析PEG沉淀后的回收率和参考区间。随后，进行回顾性分析，以评估两种定义对巨维生素B12怀疑的联合效用。共纳入297例病例。
在Alinity i平台上测定的回收率和PEG沉淀后参考区间分别为60%至107%和118至506 pmol/L。McNemar检验显示两种估计干扰的标准之间存在统计学显著差异。然而，两种方法显示出良好的一致性。在27例病例中，巨维生素B12的存在与真正的维生素B12血症共存。在我们的系列中未检测到巨维生素B12与维生素B12缺乏共存的病例。
实验室报告应包括总维生素B12浓度、回收率和PEG沉淀后维生素B12浓度及其调整后的参考区间，以更好地评估身体的维生素状态。
