Real‐World Utilization Patterns of Toxoplasmosis Diagnostic Testing in Korea: A Large‐Scale Laboratory‐Based Study

BACKGROUND: Toxoplasmosis is primarily diagnosed using serologic assays, while PCR is applied selectively in specific clinical contexts. However, data on real-world utilization patterns of toxoplasmosis diagnostic tests remain limited, particularly in settings where the disease is relatively uncommon. METHODS: We retrospectively analyzed laboratory data for Toxoplasma gondii PCR, IgG, and IgM assays performed for clinical purposes between January 2020 and December 2024 at a large referral laboratory in Korea. Test utilization patterns, test combinations, test results measured after the initial test, and factors associated with test positivity were evaluated using descriptive statistics and multivariable logistic regression analyses. RESULTS: A total of 28,668 subjects underwent at least one toxoplasmosis-related test. Serologic testing accounted for the majority of initial evaluations, whereas PCR was used infrequently and primarily as a context-dependent adjunct. IgM positivity tended to be associated with subsequent testing after the initial test, while IgG positivity was more commonly observed with increasing age. Tests performed after the initial test were variably performed. PCR positivity suggestive of acute infection was rare and was observed only in cerebrospinal fluid and vitreous fluid specimens. Overall, testing patterns varied across institutions. CONCLUSIONS: This large-scale study provides an overview of real-world toxoplasmosis diagnostic test utilization in Korea. Considerable variation was observed in test utilization patterns, including IgM use and testing performed after the initial test. Further studies incorporating clinical information are needed to clarify the clinical context and implications of these patterns.