Time courses of urinary QA levels as a function of outcome of first-line treatment of acute GVHD. Data are the mean ± SE of the molar ratio of QA to creatinine (μmol/mmol) for both patients responding to first-line corticosteroids (n = 20) and those requiring second-line treatment within 28 days (“resistant”) (n = 15); differences were significant (P < .05) for days 4 and 7.