Microtainers are preferred for specimens of small volume. It is important to pay careful attention to handling and filling of the specimen tubes.

Tubes containing anticoagulant also have a small plastic bead or donut to aid in proper sample mixing. These must be at least 1/2 full to achieve a usable anticoagulant: blood ratio. Mix well by inversion (at least 5 times) immediately after collection to prevent clotting.

Tubes without anticoagulant are filled with the requisite volume and left for at least 1/2 hour at room temperature or until clotting is achieved.

If required, centrifuge the specimen and transfer plasma or serum to a plain red-top microtainer (unless a separator tube is used which eliminates the need for transfer).

Green Top Tube, Plain (without separator gel), contains heparin, and can be used for tests requiring heparinized plasma or whole blood.

Green Top Separator Tube also contains heparin plus an inert separator gel, and is the preferred specimen for tests requiring heparinized plasma.

Lavender Top Tube contains EDTA and is generally used as the specimen of choice for avian and small mammal CBC and other studies of blood cells. Certain tests also recommend EDTA plasma (see table).

Red Top Tube, Plain (without additives) is used for any test requiring serum . After the specimen has clotted, the serum should be separated from the blood cells promptly to obtain optimum results.

Brown Top Separator Tube contains an inert separator gel which eliminates the necessity of transferring the serum to another tube after centrifugation. These tubes should not be used for measuring drug levels.

Microhematocrit Tubes (plain or heparinized), 2 or more, also can be used for some tests (see table)

* Depending on the patient's packed cell volume (PCV) about 1/3-1/2 of WB volume will be P or S. If only a small volume can be collected, use 1 plain G and do not centrifuge. Unless otherwise prioritized, a "mini" CBC will be run (PCV, estimated WBC and differential) plus as many chemistries as possible.

Antech is pleased to announce an update in the methodology we use for coccidioides serology. We will now use AGID for both IgG and IgM titers. Complement Fixation will be available for a short period of time for those monitoring patients. An AGID titer will be provided with all CF titers for comparison.

LAB TIPS

Antech's Research Department initiated a study to assess whether discrepancies exist when the total and differential WBC counts are determined by three different methods (Unopette, Estimate and Cell Dyne). With the Becton Dickinson Unopette microcollection system, leukocytes are counted in diluted blood placed in a hemacytometer. With the Estimate method, the number of leukocytes per 40 x objective, from at least five fields, are counted on a Wright's stained blood smear. The average number of leukocytes is then multiplied by 1000 to make an estimated total white cell count. The Abbott Cell-Dyne 3500 automated CBC analyzer uses a laser beam and measures the light scattered by the cells to give the total and differential leukocyte count.

Statistical analysis revealed no clinically significant difference between cell counts performed by the Estimate or Unopette methods. However, the Cell-Dyne automated instrument produced a significantly higher total leukocyte count as compared to the average result of the other two methods. Based on these findings, the Estimate or Unopette methods are recommended as an acceptable procedure for avian and reptile WBC counts.