Intra-individual variability of serum GLDH (a) and serum ALT (b). The bars with open circles represent average, minimum, and maximum values for 2 to 4 repeat measurements of serum GLDH (a) and serum ALT (b) for each of 81 subjects taken over the course of 3 wk. The dataset included 257 individual measurements. a) GLDH versus Mean GLDH (by Subject). b) ALT…