From the Universidad Miguel Hernández, and the Sección de Reumatología, Hospital General Universitario de Alicante, Instituto de Investigación Sanitaria y Biomédica de Alicante, Alicante; Sección de Reumatología, Hospital Marina Baixa, Villajoyosa, Spain.
S. Pastor, Medical Student, Universidad Miguel Hernández; J.A. Bernal, PhD, Sección de Reumatología, Hospital Marina Baixa; R. Caño, PhD, Sección de Reumatología, Hospital General Universitario de Alicante, Instituto de Investigación Sanitaria y Biomédica de Alicante; S. Gómez-Sabater, BSc, Sección de Reumatología, Hospital General Universitario de Alicante, Instituto de Investigación Sanitaria y Biomédica de Alicante; F. Borras, PhD, Departamento de Estadística, Matemáticas e Informática, Universidad Miguel Hernández; M. Andrés, PhD, Sección de Reumatología, Hospital General Universitario de Alicante, Instituto de Investigación Sanitaria y Biomédica de Alicante, Departamento de Medicina Clínica, Universidad Miguel Hernández.
J Rheumatol. 2020 Sep 1;47(9):1416-1423. doi: 10.3899/jrheum.190468. Epub 2020 Feb 1.
Lack of access to polarized light microscopy is often cited as an argument to justify the clinical diagnosis of crystal-related arthritis. We assessed the influence of time since sampling and preservation methods on crystal identification in synovial fluid (SF) samples under polarized light microscopy.
This was a prospective, longitudinal, observational factorial study, analyzing 30 SF samples: 12 with monosodium urate (MSU) crystals and 18 with calcium pyrophosphate (CPP) crystals. Each SF sample was divided into 4 subsamples (120 subsamples in total). Two were stored in each type of preserving agent, heparin or ethylenediamine tetraacetic acid (EDTA), at room temperature or at 4°C. Samples were analyzed the following day (T1), at 3 days (T2), and at 7 days (T3) by simple polarized light microscopy, and the presence of crystals was recorded.
The identification of crystals in the MSU group was similar between groups, with crystals observed in 11/12 (91.7%) room temperature samples and in 12/12 (100%) refrigerated samples at T3. Identification of CPP crystals tended to decrease in all conditions, especially when preserved with EDTA at room temperature [12/18 (66.7%) at T3], while less reduction was seen in refrigerated heparin-containing tubes.
Preserving samples with heparin in refrigerated conditions allows delayed microscopic examination for crystals. Avoiding crystal-proven diagnosis because of the immediate unavailability of microscopy no longer appears justified.
无法获得偏光显微镜通常被认为是支持晶体相关性关节炎临床诊断的论据。我们评估了时间和保存方法对关节液（SF）样本在偏光显微镜下晶体鉴定的影响。
这是一项前瞻性、纵向、观察性因子研究，分析了 30 份 SF 样本：12 份含有单钠尿酸盐（MSU）晶体，18 份含有焦磷酸钙（CPP）晶体。每个 SF 样本分为 4 个等分试样（共 120 个等分试样）。每种等分试样分别用肝素或乙二胺四乙酸（EDTA）保存在室温或 4°C 下。在第 1 天（T1）、第 3 天（T2）和第 7 天（T3）通过简单偏光显微镜进行分析，并记录晶体的存在。
MSU 组晶体的鉴定在各组之间相似，室温下的 11/12（91.7%）样本和冷藏样本的 12/12（100%）均观察到晶体。在所有条件下，CPP 晶体的鉴定均有下降趋势，尤其是在室温下用 EDTA 保存时[T3 时的 12/18（66.7%）]，而冷藏肝素管中晶体减少较少。
在冷藏条件下用肝素保存样本可延迟对晶体进行显微镜检查。由于无法立即获得显微镜检查而避免晶体确诊似乎不再合理。
