Bilirubin (total)

The yellow pigment left over when old red blood cells are broken down, reported as the direct and indirect fractions added together.

It is the number behind jaundice, and it separates a liver problem from red cells being destroyed faster than usual.

A mildly raised total with a normal direct fraction is very often Gilbert syndrome, a harmless inherited variant that affects a good few percent of people -- fasting, illness or a hard workout pushes it up in exactly that pattern.

Worth discussing a rise that comes with dark urine or yellowing.