tailieunhanh - problem oriented medical diagnosis (seventh edition): phần 2

part 2 present the content includes 5 main chapters: hematologic problems, renal electrolyte, blood gas and acid base problems, musculoskeletal problems, endocrine and metabolic problems, neurologic problems. | 6. HEMATOLOGIC PROBLEMS Anemia Robert G. Chapman Definition I. Anemia is a subnormal total red cell volume. The normal volume in men is 32 mL kg in women it is 25 mL kg. Persons living at elevations higher than 8 000 to 9 000 feet above sea level have an increased total red cell volume. Below this altitude normal increases are of smaller magnitude and difficult to detect. II. The total red cell volume can be measured with SICr- or 32P-labeled red cells or it can be calculated from the measured plasma volume and hematocrit reading. Simple tests measuring red cell concentration hemoglobin and hematocrit values red cell count are usually used in place of the expensive and time-consuming total volume determinations. A normal plasma volume is assumed in evaluating the results. Normal Values 1. The normal hemoglobin concentration in men is not less than g 100 ml in women it is not less than 12 g 100 mk The normal hematocrit value in men is not less than 41 in women not less than 36 . The normal red cell count in men is not less than milhon mm3 in women not less than million mm . Of these the red cell count is the least reliable. Automated determinations calculate the hematocrit value from the red cell count and the average individual red cell volume. Hematocrit readings obtained by this method are not as reliable as those measured directly by centrifugation. The ratio of hematocrit value to hemoglobin value is close to 3 1. Significant deviations from this ratio on automated counts should be questioned. II. Dehydration such as occurs in vomiting and diarrhea may deplete the plasma volume and produce a rise in hemoglobin or hematocrit value without changing the total red cell volume. Pregnancy and congestive heart failure on the other hand have the opposite effect. When there is a rapid loss of blood the hemoglobin and hematocrit values do not reflect the degree of blood loss until readjustment of the plasma volume has taken place. Therefore under .