Current trends in crystal identification

Pattern of gout and its association with chronic kidney disease in Maiduguri, northeastern Nigeria

INTRODUCTION

Gout is considered uncommon among Black Africans. It is commoner in men and associated with obesity, hypertension, and chronic kidney disease (CKD). This study aims to determine the pattern and frequency of gout and its associated factors in Maiduguri, north-eastern Nigeria.

METHOD

A retrospective study of gout patients managed at the rheumatology clinic of the University of Maiduguri Teaching Hospital (UMTH), Nigeria, from January 2014 to December 2021. Diagnosis of gout was made using the Netherlands 2010 criteria, and CKD was defined as an estimated glomerular filtration rate (eGFR) of < 60 ml/min/1.73m² using the 2021 CKD-epidemiology collaboration (CKD-EPI) creatinine equation. A P-value of < 0.05 was considered statistically significant.

RESULTS

Out of 1409 patients seen during the study period, 150 (10.7%) had gout. They comprised 57.0% males, mostly presented with mono-articular disease (47.7%) with the ankle predominantly involved (52.3%). First metatarsophalangeal and knee joint involvement were commoner among males than females (59% vs 39%, p = 0.052 and 55.7% vs 34.8%, p = 0.05 respectively). The mean serum uric acid (SUA) level was 557.6 ± 176.2 mmol/l, and the levels did not differ between gender (p = 0.118, CI [- 126.6 to 14.5]). Ninety (84.1%) had CKD with 20.6% in end-stage renal disease (eGFR < 15 ml/min/1.73m²). Polyarticular involvement and tophi were commoner among patients with CKD (21.1% versus 11.8% p = 0.652 and χ = 4.364, p = 0.022 respectively) Serum uric acid levels positively correlated with serum creatinine (p = 0.006) and negatively correlated with eGFR (p = 0.001). The best predictor of SUA level was the eGFR (B =  - 2.598, p < 0.001).

CONCLUSION

Gout in north-eastern Nigeria constitutes about 11% of all rheumatic diseases and is typically monoarticular; however, polyarticular form and tophi were commonly seen in patients with CKD. Further studies will be needed to evaluate the relationship between the pattern of gout and CKD in the region. Key Points • Gout in Maiduguri is commonly monoarticular; however, polyarticular presentations and tophi are commoner among gout patients with chronic kidney disease (CKD). • The increase in the burden of CKD might have resulted in the increase in the number of females with gout. • The use of the validated and simple Netherlands criteria for the diagnosis of gout is useful in developing countries to overcome the challenges associated with the use of polarized microscope and thereby allowing further research on gout. • There is a need for further research on the pattern and prevalence of gout and its relationship with CKD in Maiduguri, Nigeria.

The Diagnostic and Prognostic Value of Synovial Fluid Analysis in Joint Diseases

Liquid biopsy is an emergent test method for the diagnosis and prognosis in the clinic. Joint fluid, also known as synovial fluid, contains a variety of bioactive constituents that can be selectively detected and further evaluated in a convenient fashion. Therefore, synovial fluid analysis functions as a specific form of liquid biopsy and plays a vital role in numerous joint diseases. In spite of the component analysis of aspirated synovial fluid beingconsidered as the gold standard for diagnosis of joint infections, biopsy of joint fluid benefits the initial diagnosis and long-term prognosis of degenerative, inflammatory, autoimmune, traumatic, congenital, and even neoplastic joint diseases. The convenience and accuracy for disease evaluation are significantly elevated as a result of the combination of synovial fluid analysis and other novel clinical technologies. In this review, we shed light on the latent role of synovial fluid in the diagnosis and prognosis of articular diseases and proposed future prospects for relevant research in this field.

Gout in the Flexor Hallucis Longus Tendon Mimicking Cellulitis: A Case Report

A 65-year-old Japanese man was admitted to our hospital with fever and inflammation of the right ankle. We initiated antibiotics on suspicion of cellulitis. After no clinical improvement, we performed magnetic resonance imaging, which showed a fluid collection in the flexor hallucis longus (FHL) tendon sheath. Synovial fluid analysis revealed monosodium uric crystals. Final diagnosis was FHL tendonitis secondary to gout proven by synovial fluid analysis. To our knowledge, this is the first case report of FHL tendonitis caused by gout. When ankle inflammation is examined in clinical situations, FHL tendonitis caused by gout should be considered.

Peripheral Bacterial Septic Arthritis: Review of Diagnosis and Management

Septic arthritis refers to an infection in a joint due to a bacterial, mycobacterial, or fungal cause. Joint infections are a serious cause of morbidity and mortality and constitute a true musculoskeletal emergency. The estimated incidence of septic arthritis in the general population is between 2 and 6 cases per 100,000 people per year. The most common presentation is an acute monoarthritis. Identification of organisms in the synovial fluid is the criterion standard for diagnosis. Synovial fluid aspiration should be performed prior to initiating antibiotics. While no diagnostic cutoff exists for synovial fluid white blood cell count, increasing leukocytosis is associated with a higher likelihood of an infectious cause of arthritis, and patients commonly present with values greater than 50,000/μL. The cornerstones of treating septic bacterial arthritis are adequate drainage and antimicrobials. Joint drainage is always recommended in septic arthritis; however, no clear guidelines or strong evidence exist to guide the preferred method of drainage. Options for joint drainage include daily needle aspiration, arthroscopy, or open surgical drainage via arthrotomy.

Synovial fluid uric acid level aids diagnosis of gout

Examination of urate crystal in synovial fluid (SF) remains the gold standard for diagnosis of gout, but is not universally available. SF uric acid (UA) level may be measured by the uricase method with an automated analyzer. The present study aimed to evaluate the utility of SF to serum UA ratio (SSR) for diagnosis of gout. A cross-sectional study was conducted at the National Center for Rheumatic Diseases, Nepal. Patients presenting with acute (<1 day) joint pain and/or swelling were included. Aspiration was performed in all patients and fluid was subjected to testing for urate level, pH and cell counts and microscopy. Serum samples were also assessed for urate levels, and the SSR was calculated for each patient. A receiver operating characteristic curve was plotted to determine the cutoff value for indicating diagnosis of gout. The difference in SSR between gout and non-gout effusion was evaluated by one-way analysis of variance. A total of 181 patients were included of which 77 had gout. The remaining cases included osteoarthritis, pseudogout, rheumatoid arthritis and ankylosing spondylitis. SSR was significantly higher in gout patients than in any other group (P<0.05). An SSR of ≥1.01 had the highest sensitivity and specificity at 89.6 and 66.3%, respectively, for identifying gout effusion. The present results indicated that SSR may be used as an aid for gout diagnosis when polarizing microscopy is not available.

Performance of the Existing Classification Criteria for Gout in Thai Patients Presenting With Acute Arthritis

Currently, there are 5 existing classification criteria for gout: the Rome, New York, American Rheumatism Association (ARA), Mexico, and Netherlands criteria. This study was carried out to determine the performance of these classification criteria in Thai patients presenting with acute arthritis.All consecutive patients presenting with acute arthritis and being consulted at the Rheumatology Unit, Chiang Mai University Hospital from January 2013 to May 2015 were invited to join the study. Gout was defined by the presence of monosodium urate crystals in the synovial fluid or tissue examined by experienced rheumatologists. The 5 existing gout classification criteria were performed and evaluated in all of the patients, who were divided in subgroups of early disease (≤2 years), established disease (>2 years), and those without tophus.There were 136 gout and 97 nongout patients. Sensitivity and specificity across all criteria ranged from 75.7% to 97.1% and 68.0% to 84.5%, respectively. Overall, the Mexico criteria had the highest sensitivity (97.1%), and the ARA survey criteria the highest specificity (84.5%), whereas the Mexico criteria performed well in early disease with sensitivity and specificity of 97.1% and 81.7%, respectively. All 5 criteria showed high sensitivity (from 76.4% to 99.1%) but low specificity (from 30.8% to 65.4%) in established disease. In patients without tophus, the sensitivity and specificity ranged from 64.1% to 95.7% and 68.8% to 85.4%, respectively. The ARA survey criteria across all groups showed consistently high specificity for gout.The 5 existing classification criteria for gout had limited sensitivity and specificity in Thai patients presenting with acute arthritis. The ARA survey criteria are the most suitable for diagnosing gout in Thai people when crystal identification is not available.

Markedly elevated intra-articular white cell count caused by gout alone

Joint pain accompanied by erythema, swelling, and decreased range of motion is concerning for septic arthritis and typically warrants joint aspiration. The synovial fluid white blood cell count plays a central role in the decision-making process regarding these patients. Traditional teaching holds that a cell count greater than 50,000 white blood cells/µL is likely caused by infection and therefore warrants either operative intervention or serial aspiration. This report describes 2 patients with extremely high synovial fluid white blood cell counts in the absence of infection. Case 1 involved a 59-year-old man who presented to the emergency department with sudden onset of atraumatic left elbow pain and was found to have a white blood cell count of 168,500 white blood cells/µL on joint aspiration and innumerable monosodium urate crystals. The patient ultimately improved with treatment with oral prednisone, avoiding operative intervention. Case 2 involved a 69-year-old man who presented to the emergency department with acute onset of atraumatic left knee pain. On arthrocentesis, the patient had a cell count of 500,000 white blood cells/µL and was therefore taken to the operating room for arthroscopic irrigation and debridement. Final analysis of the synovial fluid showed monosodium urate crystals and negative culture findings. These cases illustrate the highest synovial fluid white blood cell count reported in patients with gout and highlight the potential difficulty in differentiating between acute gout and septic arthritis in the setting of markedly elevated white blood cell count.

Synovial fluid analysis for crystals

PURPOSE OF REVIEW

Describe why this review is timely and relevant. Identifying monosodium urate (MSU) and calcium pyrophosphate dehydrate (CPPD) crystals allows a quick and definitive diagnosis of both gout and CPPD arthritis, and remains the accepted gold standard. These diseases are still often diagnosed on inaccurate clinical grounds. Crystal identification has received little critical attention since its introduction, and it appears necessary to review the technique paying special attention to the possible reasons which deter clinicians.

RECENT FINDINGS

Describe the main themes in the literature covered by the article. Synovial fluid analysis for crystals is a simple procedure allowing immediate and definite diagnosis of gout and CPPD arthritis when clinics are fitted with a proper microscope and the rheumatologists appropriately trained. This review also illustrates how crystal analysis in synovial fluid can be initially approached with both the widely available ordinary light microscope and a simple polarized one and with good results.

SUMMARY

This study describes the implications of the findings for clinical practice or research. We hope that those not performing synovial fluid analysis will be stimulated to acquire or perfect the technique and obtain a compensated polarized microscope to comply with current standards.

[Ultrasonography of the first metatarsophalangeal joint in gout]

INTRODUCTION

About one half of the first gout attacks occur in the first metatarsophalangeal joint (MTPJ1); in the disease course this joint is practically inevitably affected. Radiographic evidence of bone erosions is the indication for hypouricaemic therapy in order to prevent joint destruction and nephropathy. Advantages of ultrasonography (US) comparing to conventional x-ray findings in depicting early bone erosions in various inflammatory arthropathies have been demonstrated by several studies.

OBJECTIVE

The aims of this study were to compare US and x-ray findings in the detection of MTPJ1 erosions in patients with gout, to correlate sonographic and clinical features, and to detect possible characteristic sonographic features of gout.

METHODS

Thirty patients (60 MTPJ1) with primary gout (ACR) and 10 age-matched control subjects (20 MTPJ1) with different inflammatory arthropathies were clinically evaluated. Standard dorsiplantar weight bearing and lateral weight bearing x-ray views of both feet were taken. US was performed and interpreted by an independent sonographer on the presence of bone erosions, synovial fluid, synovial hypertrophy, Doppler signal and hyperechoic spots. Statistical analysis was performed (Spearman and Pearson correlation coefficient, Wilcoxon and chi2 test.)

RESULTS

Twenty-four studied MTPJ1 had evidence of erosions, 17 only on US and seven both on x-ray and on US (Z = -4.123; p = 0.000). US findings showed that hyperechoic spots were the most prominent feature of gouty MTPJ1 (chi2 = 40.909; p = 0.000), followed by erosions and synovial fluid presentation.

CONCLUSION

US of MTPJ1 in gout discovers significantly more erosions than x-ray, which may have therapeutic implications. The evidence of hyperechoic spots (surrogate crystals) of the different size, number and orientation is a major sonographic feature of the MTPJ1 in gout, which may be of importance in the diagnosis of certain cases (low serum urate, unavailable synovial fluid or the urate crystals absence).

A Novel Strategy for the Preparation of Naturally Occurring Phosphocitrate and Its Partially Esterified Derivatives

A novel method for the synthesis of phosphocitrate (1, PC) starting from triethyl ester of citric acid and MeOPCl2 is described. The method is based on selective stepwise hydrolysis of ester moieties from the intermediate Me-O-P(O)(Cl)(Z) (Z = triethylcitrate), 4a, which also allows one to prepare partially esterified derivatives of PC with good yield and purity without chromatographic purifications.

Gout: can we create an evidence-based systematic approach to diagnosis and management?

The management of gout can be subdivided into four phases. Asymptomatic hyperuricaemia represents the basic underlying metabolic abnormality that can lead to gout. Studies are evaluating whether interventions may be indicated in some cases. Diagnostic criteria for gout and acute flares are still not well defined unless urate crystals are found. Acute attacks of gout are treated with anti-inflammatory measures and the agent of choice is often determined by attack stage, severity and comorbidities that may contra-indicate one or more agents. After attacks subside, there are asymptomatic periods during which decisions must be made about when and how to start urate-lowering measures. If hyperuricaemia persists, there is generally persistence of urate crystals in the joint. Anti-inflammatory prophylaxis is needed when urate-lowering therapy is started. Lifestyle measures should be addressed. If chronic tophaceous gout is diagnosed, urate lowering should be started without delay. New agents are under development that may help with difficult cases.