Direct bilirubin higher than total bilirubin?

Both total and direct bilirubin measure the formation of azobilirubin, which is detected at 570/660 nm. The total bilirubin reaction contains surfactant and caffeine, which solubilize “indirect” bilirubin and accelerate the reaction (1). Direct bilirubin is a component of total bilirubin and therefore should always be smaller in value. The presence of a monoclonal immunoglobulin (2220mg/dL) falsely increased thedirect, but not the total, bilirubin measurement. Hemolysis and lipemia can also interfere at high concentrations (2).