Can blood work provide a diagnosis for my cat?

Often it can. Combined with the physical exam and the history of clinical signs of what's going on at home, your cat could be diagnosed with certain diseases or problems.

Blood work can sometimes provide a definitive diagnosis. However, it often serves to guide us toward the problem area and helps inform subsequent diagnostic tests until we find an answer.

Absolutely. That's why we run it. The whole point is to determine what is going on and that's part of the puzzle. So it's one piece of it along with other diagnostics and the examination itself.