Platelet count index

Therapy, to be effective, depends upon administration of an adequate number of platelets, generally 5 X 10 in a 70 kg man or a 60 kg woman given over 15 minutes - with suitable adjustment for body surface area in children. It is mandatory that the increment is calculated and the duration of response be documented at 24 hours. The optimum practice is to relate the number infused to changes achieved in the patient by means of the corrected count index. This step anticipates the emergence of resistance that limits the value of repeated transfusions. Occasional allergic reactions have to be blocked by premedication with an intravenous injection 100 mg of hydrocortisone, 12.5 mg of phenergan and 1 g of paracetamol... 

The platelet count is determined for the blood samples emerging, aliquot by aliquot and is averaged for 5 aliquots and the number of donors. This average divided by the platelet count in the blood in the holding syringe is called the recovery index r. The platelet retention index p is defined simply as... 

About 70% of blood ascorbate is in plasma and erythrocytes (which do not concentrate the vitamin from plasma). The remainder is in white cells, which have a marked ability to concentrate ascorbate mononuclear leukocytes achieve 80-fold, platelets 40-fold, and granulocytes 25-fold concentration, compared with plasma concentration. In adequately nourished subjects, and those receiving supplements, the ascorbate concentration in erythrocytes, platelets, and granulocytes, but not in mononuclear leukocytes, is correlated with plasma concentration. Mononuclear leukocytes concentrate ascorbate independendy of plasma concentration (Evans et al., 1982). In deficiency, as plasma concentrations of ascorbate fall, mononuclear leukocyte, granulocyte, and platelet concentrations of ascorbate are protected to a considerable extent. As discussed in Section 13.5.2, the leukocyte content of ascorbate is used as an index ofvitamin C nutritional status, but in view of the differing capacity of different cell types to accumulate the vitamin, differential white cell counts are essential to interpret the results. 

The complete blood count (CBC) (1) counts RBCs, white blood cells, and platelets (2) measures Hb (3) estimates the red cells volume, and (4) sorts the white blood cells into sub-types. Knowledge of red ceU indices and the appearance of the peripheral blood film are vital to the diagnosis of both a- and P-thalassemias. Hemoglobinopathies have a lesser impact on the red ceE indices but may present abnormal red cell morphology on the peripheral blood film. In thalassemias, the Hb concentration and the mean corpuscular volume (MCV), an index of cell size, are decreased, sometimes markedly, whereas in hemoglobinopathies both are often normal. One study recommends that an MCV of less... 

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