Can dehydration affect CBC test results?

Yes, dehydration can temporarily affect CBC test results. When you're dehydrated, the volume of plasma in your blood decreases, making components like hemoglobin, hematocrit, and red blood cell counts appear higher than they actually are. This is because the blood becomes more concentrated. Once you're properly hydrated, these levels should return to normal. If your CBC results show elevated blood cell counts and you're dehydrated, your doctor may suggest rehydrating and retesting to obtain more accurate results.