What is the normal range of carboxyhemoglobin (COHb) in blood?

What is the normal range of carboxyhemoglobin (COHb) in blood?

• A. 0-2%
• B. 1-3%
• C. 2-4%
• D. 3-5%

Answer: (B)

Carboxyhemoglobin is formed when carbon monoxide binds to hemoglobin, and in people with minimal CO exposure the amount of CO bound is very small. The reference range commonly cited for healthy individuals is about one to three percent. Values outside this range suggest notable CO exposure or unusual physiology, while smokers may have higher baseline levels, the typical normal range used in exams and clinical context is around 1-3%.

Carboxyhemoglobin is formed when carbon monoxide binds to hemoglobin, and in people with minimal CO exposure the amount of CO bound is very small. The reference range commonly cited for healthy individuals is about one to three percent. Values outside this range suggest notable CO exposure or unusual physiology, while smokers may have higher baseline levels, the typical normal range used in exams and clinical context is around 1-3%.