Final answer:
Increased serum creatinine can indicate adverse effects of corticosteroids after kidney transplantation.
Step-by-step explanation:
The assessment finding that may indicate that a patient is experiencing adverse effects to a corticosteroid taken for four years after kidney transplantation is increased serum creatinine. Corticosteroids can affect kidney function, leading to an increase in serum creatinine levels. Serum creatinine is a marker that indicates how well the kidneys are functioning. Elevated levels of serum creatinine may suggest renal damage or impairment.