Can illness affect CBC test results?

Yes, an illness can affect CBC test results. For example, a bacterial infection can cause an elevated white blood cell (WBC) count as your immune system responds to the infection. Similarly, viral infections may lower white blood cell counts. Chronic conditions, like autoimmune diseases or inflammatory disorders, can also cause fluctuations in white blood cell or platelet counts. Your doctor will consider these factors when interpreting your results. It’s essential to inform your healthcare provider if you are unwell at the time of the test, as they may recommend retesting once your illness has resolved.