True regarding unconjugated bilirubin is -

Unconjugated bilirubin Unconjugated bilirubin is highly lipid soluble (lipophilic). It is insoluble in water and tightly bound to albumin → cannot be excreted in urine. Unbound fraction, which is increased in hemolytic reactions (e.g. erythroblastosis fetalis), can cross blood-brain barrier because of lipophilic nature and can cause brain damage of newborn → Kernicterus. Conjugated bilirubin Conjugated bilirubin is water soluble and only loosely bound to albumin and thus is easily filtered by glomeruli and excreted in urine.