Expression of serum LDH isoenzymes 1–5 and serum lactate in patients with metastatic melanoma. Serum samples from melanoma patients analyzed for total serum LDH and LDH1-5 (panels i-v) and serum lactate (panel vi). Dots in each of the panels represent individual patient data showing the percentage of each LDH isoenzyme, presented as percentage activity to the total serum LDH activity, or absolute serum lactate levels versus log-transformed total serum LDH. Dashed blue and red lines in each panel depict the lower or upper limits of normal for each LDH isoenzyme percentage or serum lactate activity, respectively, whereas dashed grey lines depict normal and high total serum LDH levels. All lower and upper limits of normal are based on clinical cutoffs. Pearson’s correlation coefficients ρ, with corresponding p-values, determining the association between the percentage of each LDH isoenzyme and log-transformed total serum LDH are shown in red.