Медицина 2.0

The erythrocyte sedimentation rate (ESR or sed

rate) measures the rate at which RBCs in anticoagulated blood settle to the bottom of a calibrated tube.

In normal blood, relatively little settling occurs

because the gravitational pull on the RBCs is almost

balanced by the upward force exerted by the plasma.

If plasma is extremely viscous or if cholesterol levels

are very high, the upward tre

The WBC count determines the number of leuko-

cytes per cubic millimeter of whole blood. The

counting is performed very rapidly by electronic

devices. The WBC may be performed as part of a

CBC, alone, or with differential WBC count. An

elevated WBC count is termed leukocytosis; a

decreased count, leukopenia. In addition to the

normal physiological variations in WBC count,

many pathologica

The differential WBC count indicates the percentage

of each type of leukocyte present per cubic millimeter of whole blood. If necessary for further evalua-

tion of results, the percentage for each cell type can

be multiplied by the total WBC count to obtain the

absolute number of each cell type present.

Causes of alterations in the differential WBC

count according to type of leukocyte are p

WBCs in peripheral blood samples retain enzymatic

activity and can alter substrates added in the laboratory. The presence of enzymatic activity is useful in

studying cells that are so morphologically abnormal

on stained smear that it is difficult to determine their

cell line of origin (see Fig. 1–2). The two most

common WBC enzyme tests are the test for leuko-

cyte alkaline phosphatase, an

Vascular activity consists of constriction of muscles

within the walls of the blood vessels in response to

vascular damage. This vasoconstriction narrows the

path through which the blood flows and may some-

times entirely halt blood flow. The vascular phase of

hemostasis affects only arterioles and their depend-

ent capillaries; large vessels cannot constrict suffi-

ciently to prevent bloo