Final answer:
C. Potassium 2.5
The most concerning preoperative lab result for Mr. Smith is the Potassium level of 2.5, which is considered significantly low and has potential for serious cardiac complications.
Step-by-step explanation:
When considering the preoperative lab results for Mr. Smith who is undergoing a TURP, the most concerning result would be a Potassium level of 2.5. The normal range for serum potassium is typically cited as being between 3.5 to 5.0 mEq/L. A level of 2.5 mEq/L is significantly low and can cause serious cardiac problems and abnormal heart rhythms. Therefore, this lab value poses an immediate concern and would likely require correction before the procedure can safely be performed.
The other values provided are within normal ranges: a hematocrit of 48% is normal for males, platelets at 300,000 are within the normal range, and a white blood cell count of 8,000 is also normal.