Final answer:
Elevated bilirubin levels with normal LFTs can be indicative of conditions like Gilbert's disease or Crigler-Najjar syndrome, where bilirubin processing is directly affected, or hemolytic jaundice due to excessive breakdown of red blood cells.
Step-by-step explanation:
If a patient presents with elevated bilirubin levels but other liver function tests (LFTs) are normal, several causes are possible. Two conditions that specifically affect bilirubin processing are Gilbert's disease and Crigler-Najjar syndrome. Gilbert's disease is characterized by a reduced ability of the liver to take up and process bilirubin due to lower activity of the enzyme UDP-glucuronyl transferase. Meanwhile, Crigler-Najjar syndrome arises from the absence of this enzyme's activity, leading to a build-up of bilirubin. Another potential cause is hemolytic jaundice, which occurs when there is excessive breakdown of red blood cells, surpassing the liver's capacity to remove bilirubin from the bloodstream. Infective or hepatic jaundice could also contribute, wherein liver damage from various causes, such as alcoholism or infections, impedes the liver's ability to conjugate and excrete bilirubin. Nonetheless, other LFTs like AST, ALT, and ALP might remain within normal ranges initially in these conditions.