Red blood cell indices in a high altitude hospital population.

It is currently accepted that the red blood cell indices (MCV, MCH and MCHC) are the same in general care hospital populations throughout the world. The aim of the study was to explore whether the internationally accepted values for red cell indices are the same in a hospital located in Mexico City at 2240 meters above sea level (7352 feet). The setting for the study was a third level specialized care hospital for adults with chronic degenerative problems (trauma and obstetric cases were not seen). Each day, for a period of 139 working days, 120 EDTA blood samples of patients were assayed within 3h of extraction in a flow cytometer analyzer (Coulter STKR). Using the moving average approach of Bull (Reference 3) in batches of 20 samples, a raw daily value for each indice was obtained with the mean of the six daily moving averages. The daily raw value was multiplied by a ratio (assigned/observed ratio) of the corresponding daily value obtained in a normal preserved blood control (Coulter's 4C): we refer to them as corrected values in this paper. A total of seven batches of the Coulter control were used to obtain the corrected values during the 139 days of observation. The results were as follows. The mean (SD) of correction values in the 139 days were: MCV = 90.33 (.810) fl, MCH = 30.75 (.582) pg, MCHC = 33.38 (.630) g/dl. The indices showed significant changes in mean as a function of batch of the Coulter control used (F tests, p < 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)