Volume 11, Number 03

RED CELL MACROCYTOSIS Clinical significance Macrocytosis is a term which is used to signify increased size of the red cell over an accepted normal range. It is usually expressed by the red cell index known as Mean Corpuscular Volume (MCV) which is a value calculated by dividing the hematocrit by the red cell count. The normal range in adult males and females is usually considered to be 80-97 femtolitres. The index is considered to support macrocytosis when it is equal to or greater than 100 femtolitres although some believe 105 is a better cutoff point. Using the latter figure, macrocytosis occurs in slightly less than 2% of routine blood counts of in and out-patients. Today's electronic cell counters provide this index automatically and reliably and considerable work has been done to use macrocytosis as a clue to help diagnose various conditions. One study1 identified the following causes in 107 patients with macrocytosis >105. Vitamin B 12 deficiency Pernicous anemia 22% Malabsorption 4% Folic acid deficiency Alcoholism 18% Abnormal diet 9% Malabsorption 2% Excess demands 2% Severe liver disease Alcoholic 14% Post-hepatitis 1% Hematologic Myelodysplastic syndrome 17% Leukemia, lymphoma 5% Hemolytic anemia 4% Other Cardiac insufficiency 2% COPD 3% Macrocytosis has also been reported with: Pregnancy Down's syndrome Certain drugs: Dilantin Chemotherapeutic and immunosuppressing agents Chronic renal failure Nitrous oxide abuse Infectious mononucleosis (spurious) Runner's macrocytosis (footstrike hemolysis) The presence of macrocytosis may precede the appearance of some of the diseases with which it is associated for a considerable time. For instance, a vitamin B12 deficiency may initially produce only a mild anemia with macrocytosis. These two findings may persist for months or even years and then there may be a rapid deterioration. Macrocytosis may precede deterioration in secondary myelodysplastic syndrome for 6-18 months2. It has been stated that macrocytosis is a useful diagnostic indicator of alcoholism3. Outeririno Perez JJ et al. Sangre 1989; 34(1):32-40 Dohy H et al. Clin Lab Haematol 1980; 2(2):111-119 Morgan MY et al. Clin Lab Haematol 1981; 3(1):35-44

PROSTATE-SPECIFIC ANTIGEN How useful is this tumor market? PSA is recommended in testing patients with symptoms of prostatic carcinoma, or with papable abnormalities of the prostate gland, and to monitor patients with proven prostatic carcinoma. Because PSA is more sensitive than PAP, and the use of PAP as well as the PSA does not appear to add anything, the PSA has virtually replaced the PAP in many practices. Elevations in the PSA have been noted with the occurrence of local invasion of lymph nodes, and the appearance of distant metastases. Because of this, PSA has been used for staging the disease. Obtaining the PSA level after radical prostatectomy for carcinoma has also been shown to be of value in predicting recurrence. Since prostatic tissue is supposed to be present to produce PSA, and return in PSA after radical prostatectomy should be considered a herald of a return of the carcinoma. Badalament RA et al. Postgrad Med 1990; 87(5):65-72

HEMOLYTIC ANEMIA Investigation There is a balance that normally exists between RBC destruction and RBC production. If some condition exists that causes increased destruction, then hemolytic anemia may occur although it should be noted that RBC survival time may be reduced to 1/6 of normal without the occurrence of anemia. Reticulocytosis will, however, be evident. Events may occur that impair RBC production, e.g. a viral infection, and hemoglobin levels can fall as much as 40% in one week. There are two causes of hemolytic anemia: Extracorpuscular or Extrinsic, and Intracorpuscular or Intrinsic. These two types are outlined below along with a simple diagram allowing laboratory investigation of some of the commoner types of this disease.

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