Background/Purpose: Hyperuricemia and gout aggregate in families. The objectives of this study were to estimate the prevalence of asymptomatic monosodium urate (MSU) crystal deposition in men with a parent with gout, and to describe the sites involved in early crystal deposition.

Methods: People with gout who participated in previous research at Academic Rheumatology, University of Nottingham, UK, were mailed a letter about the study accompanied by a study pack to be posted to their son(s) ≥20 years in age. Sons interested in participating returned a reply slip and underwent telephone screening to exclude gout or inflammatory arthritis. Eligible sons were invited for a study visit at which information about disease and demographic characteristics was obtained, musculoskeletal assessment performed and venesection undertaken. A trained ultrasonographer (AA) performed ultrasound of 1^st meta-tarsophalangeal joints (MTPJs), talar domes, femoral condyles, patella and triceps tendons, wrist triangular cartilage and 2^nd meta-carpophalangeal joints (MCPJs) blinded to the SUA level person specific characteristics [1]. The images were scored for double contour sign (DCS), tophus, calcification, hyaline linear bodies and effusion. Doubtful images were scored blindly by a second sonographer with >10 years’ experience (PC). This study was approved by the Nottinghamshire Research Ethics Committee-II. N (%), mean (standard deviation (SD)) were used for descriptive purpose. Chi-square tests were used to compare categorical values.

Results: 1435 parents were invited to post the study packs to their sons if applicable. 249 replies were received, 134 sons agreed to participate, and 130 of these completed assessments to date. Their mean (SD) age, body mass index, and SUA were 43.86 (11.22) years, 27.10 (4.76) kg/m², and 6.42 (1.13) mg/dl respectively. 64.6% sons had SUA >6 mg/dl, and 30% of them had MSU crystal deposition defined as presence of either DCS or tophus. All had MSU deposition at either 1^st MTPJ, and one participant had DCS at the ankle. None of the other joints had a tophus or a DCS. The prevalence of MSU deposit was 0%, 18.8%, 35.7%, 38.3% and 34.2% in those with SUA <5, 5-5.66, 5.67-6.33, 6.33-7 and >7 mg/dl respectively. Participants with MSU crystal deposition were more likely to have calcification at patellar tendons (23.1% vs. 7.7%, p=0.01).

Conclusion: Sons of people with gout frequently have asymptomatic MSU deposits. MSU crystal deposits appear at the MTPJs and in the tendons before appearing in other joints such as the ankle or the knee. In this high risk population MSU crystal deposition occurred at SUA <6.3 mg/dl which suggests that pro-nucleating changes in the connective tissue matrix may have a role in crystal deposition.

References:

[1] Naredo E, Uson J, Jimenez-Palop M, et al. Ultrasound-detected musculoskeletal urate crystal deposition: which joints and what findings should be assessed for diagnosing gout? Ann Rheum Dis 2014;73(8):1522-8.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/the-sons-of-gout-study-ultrasonographic-evaluation-of-asymptomatic-monosodium-urate-crystal-deposition-in-sons-of-people-with-gout/