| Summary: | Objective To estimate the prevalence and distribution of asymptomatic monosodium urate (MSU) crystal deposition in sons of people with gout.
Method People with gout were mailed an explanatory letter enclosing a postage-paid study-pack to mail to their son(s) ≥20 years old. Sons interested in participating returned a reply-slip and underwent telephone screening. Subsequently they attended a study-visit for blood and urine collection, and musculoskeletal ultrasonography performed blind to serum urate (SU). Images were assessed for double contour sign (DCS), intra-articular or intra-tendinous aggregates/tophi, effusion and power Doppler. Logistic regression was used to examine associations.
Results 131 sons (mean age 43.80 years, body mass index 27.10 kg/m2) completed assessments. 64.1% had SU ≥6 mg/dl, and 29.8% had either DCS or intra-articular aggregates/tophi in ≥1 joint. All participants with MSU deposition had involvement of either 1st metatarsophalangeal joint. 21.4% had intra-tendinous aggregates, and these associated with intra-articular MSU crystal deposits (aOR (95%CI) 2.96(1.17-7.49)). No participant had MSU crystal deposition at SU ≤5 mg/dl, and 24.2% participants with SU between 5-6 mg/dl had ultrasonographic MSU deposition. MSU crystal deposition associated with increasing SU (aOR (95%CI) 1.61(1.10-2.36) for each 1 mg/dl increase).
Conclusion Asymptomatic sons of people with gout frequently have hyperuricemia and MSU crystal deposits. In this study MSU crystal deposits were present in participants with SU >5 mg/dl. Evaluation of people without a family history of gout is needed to confirm if the threshold for MSU crystal deposition is also lower in the general population.
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