modifications of the Sahli-Hellige method, and
100 percent may be equal to from 13.8 g to 17.3 g.
In the sets usually used in the Navy, however, 100
percent is equal to 14.5 g of hemoglobin per 100
ml of whole blood. After reading the percentage
on the scale, turn the tube and read from the other
side to get the equivalent reading in grams.
If either scale is hard to read, remember that
100% ÷ 14.5 g = 6.9, so one gram of
hemoglobin is equal to 6.9 percent. If only one
scale can be read, the other reading can be
Caution: Equipment must be clean and dry
before determination is started. Wipe all blood
from the outside of the pipette before you insert
it into the tube. Twenty cubic millimeters is a small
volume, and a few blood cells clinging to the out-
side of the pipette can cause a significant error
HEMATOCRIT (PACKED CELL
Hematocrit is the volume of erythrocytes ex-
pressed as a percentage of the volume of whole
blood in a sample. The venous hematocrit agrees
closely with the hematocrit obtained from a skin
puncture; both are greater than the total body
hematocrit. Dried heparin, balanced oxalate, or
EDTA is satisfactory as an anticoagulant.
Although the microhematocrit method is not
available at all duty stations, it is the most ac-
curate means of determining blood volume and
should be used whenever feasible. This test is
rapidly replacing the red cell count for general
purposes since it is easier, quicker, and more ac-
curate. The method described here is the micro-
Normal Values. The normal hernatocrit for
males is 42 to 50 percent, for females, 40 to 48
percent. A value below an individuals normal
range for sex and age indicates anemia.
Capillary tubes, plain or heparinized
Modeling clay sealant or microburner
Fill the capillary tube two-thirds to three-
quarters full with well-mixed, oxalated
venous blood or fingertip blood (for finger-
tip blood use heparinized tubes, and invert
several times to mix).
Seal one end of the tube with clay or seal
the empty end of the tube in a small flame
of a microburner.
Place the filled tube in the microhematocrit
centrifuge, with the plugged end away from
the center of the centrifuge.
Centrifuge at a preset speed of 10,000 to
12,000 rpm for 5 minutes. If the hematocrit
exceeds 50 percent, centrifuge for an ad-
ditional 3 minutes.
Place the tube in the microhematocrit
reader. Read the hematocrit by following
the manufacturers instruction on the
microhematocrit reading device.
WHITE BLOOD CELL (LEUKOCYTE)
The total white cell count determines the
number of white cells per cubic millimeter of
blood. A great deal of information can be derived
from white cell studies. The white cell count and
the differential count are common laboratory tests
and almost a necessity in determining the nature
and severity of systemic infections.
Normal Values. The normal range is 4,000 to
11,000 cells per cubic millimeter of whole blood.
Abnormal White Blood Cell Count
1. Leukocytosis (abnormally high count).
This may be caused by:
Systemic or local infections (usually due
to bacteria). These counts are highly
variable and not diagnostic. Some in-
fections and representative white cell
(1) pneumonia20,000 to 30,000/mm3
(2) meningitis20,000 to 30,000/mm3
(3) appendicitis 10,000 to 30,000/
Dyscrasia of blood-forming tissues.
This is not caused by any known
bacteria, but is due to a malfunction-
ing of the marrow and lymph tissues,
resulting in extremely high white cell
which sometimes exceed
This is commonly
known as leukemia, or blood cancer.