Bilirubin (indirect)

The fraction the liver has not processed yet, calculated as the total minus the direct fraction.

It rises either because red cells are being broken down faster than usual, or because the liver is conjugating slowly -- which is what Gilbert syndrome is.

Because it is a subtraction of two measurements it carries the error of both, so small values are noisy. Fasting before the draw raises it noticeably in anyone with Gilbert syndrome.

Worth discussing a rise that comes with a falling hemoglobin.