Background:Soluble Klotho (S-Klotho) is an anti-aging protein mainly secreted by the kidneys. Hyperuricemia is prevalent among middle-aged and elderly individuals, which affects the development of various chronic diseases. However, there are relatively few studies investigating the association between plasma S-Klotho levels and hyperuricemia in middle-aged and elderly individuals. This study sought to clarify the relationship between S-Klotho and the risk of hyperuricemia in middle-aged and elderly people.Methods:During 2007-2016, a total of 50,588 people participated in the National Health and Nutrition Examination Survey. Finally, 12,498 middle-aged and elderly people (aged 40-79) completed the soluble Klotho tests and had obtained complete data. S-Klotho was detected by ELISA kit, and the relationship between S-Klotho and hyperuricemia was assessd by multiple logistic regression. Hyperuricemia is defined as serum uric acid levels higher than or equal to 420 mmol/L in men and 360 mmol/L in women.Results:In the middle-aged and elderly, plasma S-Klotho levels were negatively correlated with hyperuricemia, and there was a saturation effect. The inflection point of S-Klotho was 850.9 pg/ml (logarithmic likelihood ratio test <0.001). When plasma S-Klotho <850.9 pg/ml, the prevalence of hyperuricemia in middle-aged and elderly individuals with higher levels of S-Klotho decreased by 27.1% compared with those with low levels of S-Klotho[Q4 vs Q1, OR: 0.729, 95%CI: (0.615, 0.863), P < 0.001]; In different age groups, S-Klotho had a significantly greater effect on hyperuricemia in middle-aged people[Age: 40-65years, Q4 vs Q1, OR(95%CI): 0.64, (0.55, 0.76), P <0.001; Age>65 years: Q4 vs Q1, OR(95%CI): 0.67, (0.53, 0.85), P =0.001)] .When the level of S-Klotho was higher, the risk of hyperuricemia in men was lower than that in women [male: Q4 vs Q1, OR(95%CI): 0.64, (0.53, 0.77), P <0.001; female: Q4 vs Q1 (95%CI):0.66, (0.54, 0.81), P <0.001].Conclusions:In middle-aged and elderly individuals, plasma S-Klotho levels were inversely correlated with hyperuricemia, with a saturation effect. Given the limitations of the research results, the underlying mechanism between S-Klotho and hyperuricemia should be further explored.