Thrombin-antithrombin (TAT) levels before and after lepirudin treatment in patients with acute isolated HIT (n = 8) and in patients with HIT and thrombosis n = 47⁹ . Medians and 25% and 75% quartiles are given. The normal range for TAT levels is 1.0 to 4.1 μg/L (dotted line indicates upper limit). In patients with isolated HIT, TAT levels decreased from a median of 18.5 μg/L (range, 2.4-59.3 μg/L) to a median of 6.79 μg/L (range, 3.2-37.1 μg/L); in the patients with HIT and TECs they decreased from a median of 29.3 μg/L (range, 0.3-448.9 μg/L) to 9.1 μg/L (range, 4.3-377.8 μg/L).⁹  A + indicates the mean.