The P50 of a hemoglobin for oxygen (partial pressure of oxygen at which the hemoglobin is 50% oxygenated) can be estimated from a blood gas analysis of venous blood.
(1) pH of the venous blood sample
(2) PvO2 in mm Hg
LOG10(PvO2 in mm Hg if the blood was at pH 7.4) =
= LOG10(PvO2 in mm Hg measured) - (0.5 * (7.4 - (measured pH)))
1/k = X =
= (10^(2.7 * LOG10(PvO2 at pH 7.4))) * (100- (PvO2)) / (PvO2)
AS REC P50 standard =
= 10^(LOG10(X) / 2.7)
• 2.7 is the Hill constant for hemoglobin A.
P50 for the Hemoglobin
< 17 mm Hg
mutant hemoglobin with high oxygen affinity
17 to 35 mm Hg
hemoglobin with normal oxygen affinity
> 35 mm Hg
mutant hemoglobin with low oxygen affinity
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Specialty: Hematology Oncology, Clinical Laboratory