Final answer:
A nurse identifying an adverse effect of sulfasalazine in a client with ulcerative colitis should consider a low WBC count of 4,000/mm³ as a potential indicator of leukopenia, an adverse effect of the medication.
Step-by-step explanation:
The student's question is regarding the identification of an adverse effect of sulfasalazine when reviewing the laboratory results of a client with ulcerative colitis. Among the listed lab values, a white blood cell (WBC) count of 4,000/mm³ could be indicative of an adverse effect, specifically leukopenia, which is a decrease in the number of white blood cells. This count is considered to be on the lower side of the normal range, and for a patient taking sulfasalazine, it may raise concern for an adverse effect of this medication. Other values presented such as total bilirubin, platelet count, and creatinine are within normal limits and do not typically suggest an adverse reaction to sulfasalazine. Therefore, the abnormal laboratory finding that the nurse should identify as a potential adverse effect of sulfasalazine in treating ulcerative colitis is the low WBC count.