Elsevier

Joint Bone Spine

Volume 80, Issue 3, May 2013, Pages 287-290
Joint Bone Spine

Original article
Prevalence of calcium pyrophosphate and monosodium urate crystals in synovial fluid of patients with previously diagnosed joint diseases

https://doi.org/10.1016/j.jbspin.2012.08.006Get rights and content

Abstract

Objective

The main aim of this study was to investigate the frequency of monosodium urate (MSU) and calcium pyrophosphate (CPP) crystals in synovial fluid (SF) obtained from patients with previously diagnosed joint diseases.

Methods

We reviewed the results of SF analysis of 5020 samples identifying those collected from patients with a previously definite diagnosis (2370 samples). SF analysis results, age, sex, diagnosis and disease duration were recorded from computerized records of patients’ archives.

Results

The prevalence of CPP crystals in SF was 22.28% in osteoarthritis (OA), 8.28% in rheumatoid arthritis (RA), 3.82% in psoriatic arthritis (PsA), 2.79% in other spondyloarthropathies (SpA), 10% in septic arthritis (SeA), 0.66% in gout and 9.18% in the miscellanea of joint diseases, respectively. The prevalence of MSU crystals in SF was 0.30% in RA, 3.34% in PsA, 0.70% in other SpA, 0.80% in acute CPP crystal arthritis (CPP-CA), 0% in OA, reactive arthritis (ReA), SeA, juvenile idiopathic arthritis (JIA) and miscellanea.

In OA group, we observed that age and SF inflammatory indices were higher in SF positive to CPP crystals with respect to those without crystals (P < 0.0001). In RA, we found that the group of patients with CPP crystals was significantly older (P = 0.001) and had a SF less inflammatory (P = 0.022) with respect to that without crystals but with a higher disease duration than those without crystals.

Conclusion

Crystals can be detected more frequently than expected in SF from joint diseases with a previous established diagnosis. This highlights the importance of SF analysis for the diagnosis of possible comorbidities linked to the presence of crystals.

Introduction

Synovial fluid (SF) analysis is one of the most useful laboratory procedures for the diagnosis of joint diseases [1], [2]. This analysis is recommended in all SF samples obtained from undiagnosed inflamed joints and it is mandatory in the suspect of septic or crystal induced arthritis [3].

Monosodium urate (MSU) and calcium pyrophosphate (CPP) crystal identification in SF allows the immediate diagnosis of gout and CPP related arthropaties, respectively. Furthermore, they may be found in joint diseases with a previous established diagnosis, providing matter for a possible associated or coexisting disease. Sometimes, the presence of CPP crystals, although insufficient to fit the diagnosis of a true CPP deposition disease [4] may be able to influence the local inflammatory reaction.

However, very few data are available on the prevalence of MSU and CPP crystals in some relevant joint diseases, such as rheumatoid arthritis (RA), spondyloarthropathy (SpA) including psoriatic arthritis (PsA) or reactive arthritis (ReA), and septic arthritis (SeA).

In this study, we report the frequency of MSU and CPP crystals in SF obtained from patients with previously diagnosed joint diseases, by evaluating retrospectively the results of 10 years of SF analysis performed in our Rheumatology Unit.

Section snippets

Methods

The study was retrospective. We reviewed the results of SF analysis of 5020 samples collected from outpatients undergoing arthrocentesis for non-traumatic joint effusions presenting at the rheumatology unit of the University of Padova between January 2000 and December 2010 and identified those with a definite diagnosis made by a rheumatologist and based on clinical examination and radiographic findings.

When more than one SF analysis data was found for the same patients, only the first was

Results

As depicted in Fig. 1, out of the 5020 SF examined, 2049 were excluded from the study due to doubtful diagnosis or missing data for diagnosis while 601 were excluded as they came from the same patient.

Table 1 shows the total number of SF analysis considered with subject characteristics subdivided according to the type of disease.

The table reports the frequency of SF crystals in OA, RA, PsA, ReA, non PsA non ReA SpA, gout, acute CPP crystal arthritis (CPP-CA), SeA, and juvenile idiopathic

Discussion

Our study shows the prevalence of CPP and MSU crystals in SF obtained from patients with previously diagnosed joint diseases. The main aim of this study was to investigate the coexistence or the association between CPP and MSU crystals with other well established joint diseases.

With the obvious exception of gout, in which they were found in the 97.7% of cases, MSU crystals were rarely observed in SFs. In this context, the disease in which MSU crystals were most frequently identified was the PsA

Disclosure of interest

The authors declare that they have no conflict of interest concerning this article.

References (18)

There are more references available in the full text version of this article.

Cited by (53)

  • Synovial fluid analysis: Relevance for daily clinical practice

    2023, Best Practice and Research: Clinical Rheumatology
  • Concurrence of rheumatoid arthritis and calcium pyrophosphate deposition disease: A case collection and review of the literature

    2018, Seminars in Arthritis and Rheumatism
    Citation Excerpt :

    Gerster et al. [4] noted presence of both RA and CPDD to be associated with more frequent joint prosthesis, and found that the prevalence of CPP crystals in RA joints was much higher at 25.8% than previously suspected. In a large study of synovial fluids, 8% of patients with RA had CPP crystals present [9]. Theiler et al. [10] found CPP crystals in 17.7% of 113 synovial fluid specimens from RA patients.

  • Experience and satisfaction with a multidisciplinary care unit for patients with psoriasis an psoriatic arthritis

    2019, Reumatologia Clinica
    Citation Excerpt :

    Patients with psoriasis and PsA show a high prevalence of comorbidities and risk factors, among which the most important are cardiovascular disease and metabolic syndrome.19–21 Other frequent comorbidities are hyperuricemia and gout.22 We found the same results in our patients.

View all citing articles on Scopus
View full text