Mean plasma levels of NAD⁺, Total NAD(H), and NAD⁺/NADH ratio across tertiles of plasma urea (on the left), and corresponding linear graphs for the association between levels of plasma urea, and NAD⁺, Total NAD(H) and NAD⁺/NADH ratio (on the right).

*Data represented as square root NAD+, **Data represented as base-10 log-transformed Total NAD+ and NADH, and NAD+/NADH ratio. a significantly different compared to 1st tertile, b significantly different compared to the 2nd tertile.