Q: How does cyanosis correlate with hemoglobin in methemoglobinemia?
Answer: In methemoglobinemia, cyanosis correlates with total amount of methemoglobin. The formula is
total hemoglobin x percent methemoglobin = total methemoglobin
Once the total methemoglobin >1.5 g/dL, cyanosis occurs
●A patient with total hemoglobin of 9 g/dL who has 10 percent of methemoglobin will have total methemoglobin of 0.9 g/dL and will not be cyanotic.
●A patient with total hemoglobin of 16 g/dL who has 10 percent methemoglobin will have total methemoglobin of 1.6 g/dL and will be cyanotic.
In other words, anemia can mask cyanosis. This is why some individuals with acquired methemoglobinemia in anemia can be quite ill despite lack of cyanosis.
#hematology
Reference:
Josef T Prchal- Methemoglobinemia - © 2022 UpToDate ; Link: https://www.uptodate.com/contents/methemoglobinemia
No comments:
Post a Comment