Which of the following CBC findings is commonly associated with cystic fibrosis?

• A. Low Hb and Hct
• B. Normal Hb and Hct
• C. Elevated WBC count
• D. Elevated Hb and Hct concentration

Answer: (D)

Chronic lung disease in cystic fibrosis often leads to reduced oxygen levels, so the body compensates by increasing red blood cell production. The kidneys release more erythropoietin in response to hypoxemia, boosting red cell mass and raising hemoglobin and hematocrit on a CBC. If dehydration accompanies illness, plasma volume drops and the hematocrit can rise even more, creating a pattern of elevated Hb and Hct that fits CF. An elevated white blood cell count would point more to an acute infection, while low or normal Hb/Hct would not reflect the typical chronic hypoxemia seen in CF.