Final answer:
Jaundice is the clinical presentation observed when bilirubin levels are increased in the blood, resulting in a yellow discoloration of the skin and mucous membranes.
Step-by-step explanation:
When bilirubin is increased in the blood, the clinical presentation observed is jaundice. Jaundice is characterized by yellowing of the skin, mucous membranes, and sclera of the eyes, which occurs due to the accumulation of bilirubin, a bile pigment that is typically processed and removed by the liver. When the liver cannot effectively remove bilirubin from the circulation, commonly due to liver diseases or conditions leading to excessive destruction of red blood cells, the excess bilirubin diffuses into peripheral tissues, giving them a yellow coloration. This excessive level of bilirubin, known as hyperbilirubinemia, is particularly evident in conditions such as thalassemia, where abnormal synthesis of globin proteins and excessive destruction of erythrocytes lead to elevated bilirubin levels in the blood.