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Operator’s Manual – OPTI CCA-TS THB/SO2-1
ANALYTES
tHb/SO
2
Total Hemoglobin Concentration (ctHb) and
Hemoglobin Oxygen Saturation (SO
2
%)
Clinical Significance
1
total Hemoglobin concentration (ctHb)
The hemoglobin is the main component of erythrocytes. It serves as the vehicle for transportation of
oxygen within the bloodstream and each gram of hemoglobin can carry 1.39 mL of oxygen. The oxygen
combining capacity of the blood is directly proportional to the hemoglobin concentration rather than to
the number of red blood cells (RBC), because some red cells contain more hemoglobin than others.
Although oxygen transport is the main function of hemoglobin, it also serves as an important buffer in
the extracellular fluid. Decreases in the amount of hemoglobin can come about as a result of a decreased
concentration of hemoglobin in the erythrocytes, or a decreased number of erythrocytes that contain a
normal concentration of hemoglobin.
Decreased levels are found in anemia states, hyperthyroidism, severe hemorrhage and hemolytic reactions
due to transfusions of incompatible blood, reaction to chemical, infectious and physical agents as well
as various systemic diseases. Increased levels are found in hemoconcentration of the blood, chronic
obstructive pulmonary disease and congestive heart failure.
c tHb gives valuable information in an emergency situation if interpreted not in an isolated fashion but in
conjunction with other pertinent laboratory data.
c tHb is used to screen for disease associated with anemia, to determine the severity of anemia, to follow
the response to treatment for anemia and to evaluate polycythemia.
Hemoglobin Oxygen Saturation (SO
2
%)
When each heme group of the hemoglobin molecule is associated with one molecule of oxygen, the
hemoglobin is referred to as oxyhemoglobin (O
2
Hb). The amount of oxyhemoglobin, expressed as a
fraction of the total functional hemoglobin (able to bind oxygen), is termed hemoglobin oxygen saturation
( S O
2
%). The largest portion (about 98%) of blood oxygen content is the oxygen bound to hemoglobin.
The reference interval for arterial blood from healthy adults is typically 94 to 98% 2. Decrease in S O
2
below the critical level necessary for tissue oxygen saturation is a grave clinical situation. Low oxygen
saturation may be caused by many of the same factors responsible for arterial hypoxemia . Low fractional
oxyhemoglobin ( F O
2
Hb), defined as a fraction of total available hemoglobin, may also be caused by
unusually large amounts of non-functional hemoglobins, high concentrations of deoxyhemoglobin,
chemically altered hemoglobin or factors affecting the affinity of hemoglobin for oxygen, including:
temperature, pH,
P
CO
2
, 2,3-DPG concentration and type of hemoglobin
.3