Fig. 5: Serum and seminal fluid concentrations of sRANKL in relation to semen quality.

a (left) Serum sRANKL (pmol/L), (middle) seminal sRANKL (pmol/L), and (right) seminal/serum sRANKL ratio in healthy (blue) and infertile men (red), (left panel; p < 0.0001, middle; p < 0.0001, right; p < 0.0001). b Longitudinal measurements of seminal sRANKL levels in 31 infertile men with an average of 14 days between sample collections. c Semen quality variables and seminal sRANKL levels in a pooled linear regression model of both healthy and infertile men. d Seminal sRANKL levels and semen quality stratified in groups according to WHO references for normal (blue) vs. low (red) semen quality, (left panel; p = 0.096, left middle; p = 0.041, right middle; p = 0.0009, right; p = 0.0034). Pooled analyses of all healthy and infertile men. e Seminal/serum sRANKL ratios and semen quality stratified in groups according to WHO classification of normal vs. low semen quality, (left panel; p < 0.0001, left middle; p = 0.005, right middle; p < 0.0001, right; p < 0.0001). Pooled analyses of all healthy and infertile men. f Receiver operating characteristic (ROC) curve analysis and table showing sensitivity and 1-specificity for semen quality variables, seminal sRANKL, and sRANKL seminal/serum ratio as well as area under the curve (AUC) with 95% confidence intervals (CI). g Sex steroid levels in serum and seminal sRANKL levels in a linear regression model of both healthy and infertile men. All beta and p-values are adjusted for duration of abstinence. Statistical tests: two-sided Student’s t test (a, d, e) and linear regression model (c, g) with *p < 0.05, **p < 0.01, ***p < 0.001.