RESUMO
PURPOSE: To assess the blood volume (BV) of children by using different prediction formulas (PF) and to confirm the value of these in providing reference estimates. PATIENTS AND METHODS: The results of BV measurements in 19 children, performed at the Department of Physiology of the Haematology and Immunology Institute, were studied. The children had been sent to this centre to define the diagnosis of anaemia (11 cases) or polycythaemia (8 cases). Four adult and 2 children formulas based on body measurements were applied in order to estimate the reference BV. The relationship between the measured red cell volume (RCV) and plasma volume (PV) and the reference values was calculated for each formula, and the results were evaluated by establishing the normality criteria. RESULTS: The PF used provided reference estimates of the different BV for a given patient. It was found that most adult formulas gave RCV and PV estimates which differ from those of children. PV was commonly decreased with all the formulas. CONCLUSIONS: The different PF provide distinct BV estimates in most patients, and coincidentally the results differ in any given child. The formulas applied to adults, based on weight and height or body surface, should not be applied to estimate the BV in children. The use of equations based on height is recommended, correlating the BV assessment with the results of other studies.