In Normal Controls, a Lower Hb Concentration and Female Sexe Increases Coagulability on the Thrombelastograph (TEG).

Background. The TEG is used in situations were point of care testing of hemostasis is desired, although its value is still controversially because of insufficient test validation. The main parameters of the TEG are (a) the reaction time (R), the time until the initial fibrin formation and comparable with the coagulation times PT and APTT; (b) clotting time (K), the time until a fixed level of clot firmness is reached; (c) the angle (alpha) is closely related to K and measures the rapidity of fibrin build up and gives information about the clot strength; R, K and alpha are prolonged by anticoagulants and factor deficiencies; (d) maximum amplitude (MA) is a measurement of maximum strength or stiffness of the developed clot; it is especially influenced by platelets and fibrin.

Methods. We performed a multivariate analysis using the Cox multiple-regression model to study the effects of sexe, age, Hb, platelet count, PT, APTT and fibrinogen on the TEG parameters.

Results. Ninety nine normal controls (54 men) age 51 ± 17 years (range 19–87) were studied; no anticoagulants, antithrombotics or oral contraceptives were used. Native whole blood samples were used. The R is significantly influenced by sexe (p<0.001; r=0.4) and APTT (p<0.001; r=0.4); R is in women 19 ± 4, versus 24 ± 5 minutes in men. K is significantly influenced by Hb (p<0.001; r=0.5), fibrinogen (p<0.001; r=−0.4), platelet count (p=0.01; r=−0.3), sexe (p=0.018; r=−0.5) and APTT (p=0.009; r=0.4). The alpha is significantly influenced by the Hb (p<0.001; r=−0.5), fibrinogen (p=0.001; r=0.4), sexe (p=0.008; r=0.5) and APTT (p=0.03; r=−0.4). In normal controls with a Hb of resp.< 8, 8–9 or >=9 mmol/l the K was resp. 6.8 ± 1.7, 8.5 ± 2.5 and 10.5 ± 2.8 minutes; the alpha was resp. 31.4 ± 8.1, 26.1 ± 7 and 21.4 ± 5.8 degrees. The MA was significantly influenced by fibrinogen (p<0.001; r=0.5), age (p<0.001; r=0.5), sexe (p<0.001; r=0.4), platelet count (p=0.02; r=0.2) and PT (p0.03; r=0.1).

Conclusion.. Coagulability measured in the TEG is increased in women compared to men (shortened R and K, larger alpha, increased MA) and coagulability increases with a decrease of the Hb concentration (shortened K and larger alpha).