Persistence of Crystals in Stored Synovial Fluid Samples.

Sonia Pastor, José-Antonio Bernal, Rocío Caño, Silvia Gómez-Sabater, Fernando Borras, Mariano Andrés

Journal: The Journal of rheumatology 2021;47(9):1416-1423

PMID: 32007932

Abstract

OBJECTIVE

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.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

Address: 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.; 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. [email protected].; 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. [email protected].

DOI: 10.3899/jrheum.190468

Link outs

Subscription / membership required

Full Text Sources:

http://www.jrheum.org/lookup/pmidlookup?view=long&...

MeSH Terms: Calcium Pyrophosphate, Crystallization, Humans, Prospective Studies, Synovial Fluid, Uric Acid