Combination of immunoadsorption and CD20 antibody therapy in a patient with mixed connective tissue disease.

or discontinue AZA/MTX had been made at consultant level, despite previous reports that transaminase elevations may be found in myositis [2–4] and other muscle diseases [4–6]. Transaminases are important intracellular components of metabolic function in many cells, including those of muscle, and elevated ALT levels may reflect transaminase leakage into the bloodstream, due to myofibrillar damage, in a manner analogous to lactate dehydrogenase and creatine phosphokinase (CPK) leakage [7]. The purpose of this ethically approved study was to examine the relationship between serum ALT and CPK levels in myositis patients, in order to establish whether ALT levels could be predicted from CPK levels. From the Salford adult-onset myositis (disease onset after 18 yr of age) database, 61 patients were identified with probable or definite myositis, according to Bohan and Peter criteria [8, 9]. Of these patients, 18 had DM, 22 PM and 21 PM as part of a connective tissue disease overlap. In a retrospective analysis of these 61 patients' data, 208 occasions were identified when their ALT, CPK and alkaline phosphatase (ALP) levels were measured together in the same laboratory, and where all the results were available. As this study was retrospective, the results of other hepatic transaminases or-glutamyl transferase were not available , so ALP was used instead as a surrogate 'other' marker of hepatic function. Correlations between the log-converted values of ALT, CPK and ALP were made using linear regression analysis and scatter-graph plots were constructed. The results demonstrated a strong correlation between serum CPK and ALT An equation of the line can be derived from the Fig. 1, describing the correlation between log CPK/ALT values [log CPK ¼ 1.47 Â (log ALT þ 0.18)], and allows prediction of ALT levels from measured CPK levels. For instance, a myositis-induced CPK rise to double the upper normal limit, i.e. to 390 U/l (log value 2.59), would be associated with an ALT level still just within the laboratory normal upper limit, of 50 U/l (log value 1.7), while a myositis-induced ALT rise to 100 U/l would not be expected until CPK levels had risen to around 1000 U/l. That not all rheumatologists appreciate that ALT rises occur in active myositis was the stimulus for this brief study. The knowledge that CPK and ALT correlate so well and that ALT levels can be predicted from CPK levels should reassure those treating myositis patients that ALT elevations are probably of muscle …