Reduced fibrin clot lysis in Klinefelter syndrome associated with hypogonadism.

Objective: Klinefelter syndrome (KS) is associated with increased risk of thrombosis. Hypogonadism and accumulating body fat in KS have a potential impact on fibrinolysis. In this study, we assessed the fibrinolytic system and the association with testosterone levels in KS. Design: This study is a cross-sectional comparison of men with KS and age-matched male controls. Methods: Fibrin clot lysis was evaluated by turbidity measurements and by measuring levels of individual fibrinolytic proteins in plasma samples. Fibrin clot structure was evaluated by scanning electron microscopy. Total testosterone was measured by liquid chromatography-tandem mass spectrometry. Body fat was evaluated by dual-energy X-ray absorptiometry. Results: In this study, 45 men with KS and 45 age- and education-matched controls were included. Men with KS had a 24% reduction in fibrin clot lysis compared with controls (46.2 ± 17.1 vs 60.6 ± 18.8 %/h, P = 0.0003) and higher levels of fibrinogen, factor XIII (P ≤ 0.01), and plasminogen activator inhibitor type 1 (P = 0.04). Men with KS had lower total testosterone (P = 0.008) and higher body fat (P = 0.001). In KS, reduced fibrin clot lysability was associated with higher fibrinogen and body fat related to decreasing total testosterone and hypogonadism among men with KS. Fibrin clot structure was not different compared to KS and controls. Conclusions: Fibrin clot lysis in KS was markedly reduced, potentially contributing to a prothrombotic state and increasing thrombotic risk. Hypogonadism in KS was associated with increased fibrinogen and total body fat, predicting reduced fibrin clot lysis.

Testosterone treatment and association with thrombin generation and coagulation inhibition in Klinefelter syndrome: A cross-sectional study.

BACKGROUND: The background for the increased occurrence of thrombosis seen in Klinefelter syndrome (KS) is unknown. The aim was to compare thrombin generation and coagulation inhibition between men with KS and controls, and to investigate whether coagulation in KS was associated with testosterone treatment (TT), and as such, measures of androgen action. METHODS: Untreated men with KS (U-KS) or testosterone treated men with KS (T-KS) were included. KS groups were matched by age and education to groups of control males with no history of TT. Blood samples were collected after overnight fasting. Low tissue factor (1pM) thrombin generation was expressed as lag time (min), time to peak (min), peak (nmol/L), and endogenous thrombin potential (nmol/L × min, ETP). Coagulation inhibitors, sex hormones, and haematocrit were measured. Matched groups were compared by Student's t-test or Wilcoxon rank sum test. Among KS, TT status as an outcome predictor was evaluated by linear regression. RESULTS: 18 U-KS and 27 T-KS with corresponding controls participated. Thrombin generation was not different comparing U-KS and T-KS with respective control groups. Among KS, ETP was lower in T-KS compared with U-KS and inversely associated with testosterone, LH-testosterone ratio and haematocrit. CONCLUSION: Neither U-KS nor T-KS expressed a pro-coagulant state compared with controls. Thrombin generation among KS was inversely associated with androgen action and lower in T-KS compared with U-KS. Whether TT is capable of lowering thrombotic risk among men with KS needs to be assessed prospectively.