Has high L-gulonate 3-dehydrogenase activity. It also exhibits low dehydrogenase activity toward L-3-hydroxybutyrate (HBA) and L-threonate. L-gulonate + NAD(+) = 3-dehydro-L-gulonate + H(+) + NADH Inhibited by malonate. Homodimer. Widely expressed, with highest levels in liver and kidney. Belongs to the 3-hydroxyacyl-CoA dehydrogenase family. Unknown reasons.