High mean red cell volume: its incidence and significance in routine haematology.

Abstract

SUMMARY With the advent of electronic particle counters of the Coulter S type the mean cell volume (MCV) has become an integral and useful feature of the red cell profile. Abnormally high values, often of minor degree, are particularly common but their precise clinical significance may be difficult to establish. This study defines the normal range and determines the incidence and distribution of the high MCV in routine hospital practice. Two hundred consecutive adult patients with an MCV of 100 fl or more were identified from the Coulter S analysis of 6542 blood samples and the underlying cause was established in 800%. Some of the clinical and economic implications of these findings are presented and briefly discussed.Red cell size has for many years been used to classify anaemia (Wintrobe, 1930). Early studies employed diffraction (Pijper, 1919) or the painstaking measurement of projected images (PriceJones, 1933) to detect changes in cell diameter in addition to the microscopic inspection of fixed and stained blood films with or without the aid of an eyepiece micrometer (Thorell, 1964). More recently cell size was related to mean cell volume (MCV), an index derived from the red cell count and packed cell volume. The adoption of this measurement, however, was restricted by the inaccuracies associated with visual red cell counting (Biggs and Macmillan, 1948) and the centrifuged haematocrit (England et al., 1972).A radical change followed the advent of electronic particle counters employing gating techniques (Mattern et al., 1957) that facilitated the rapid measurement of red cell volumes and their subsequent computation as MCV. While the electronically derived MCV has been generally regarded as more accurate than that of earlier methods it harbours several sources of error (England and Down, 1976) and, in our view, has also created new clinical, laboratory, and economic problems.The high capital cost, automation, and large work capacity of such instruments have all contributed towards the centralisation of routine "Present address:

Determinants and characteristics of mean corpuscular volume and hemoglobin concentration in white HFE C282Y homozygotes in the hemochromatosis and iron overload screening study

“…As confirmed in the present study, patients with hemochromatosis and HFE C282Y homozygosity diagnosed in medical care rarely have extreme macrocytosis (MCV > 110 fL) and anemia [3,8,10] that are sometimes associated with deficiency of vitamin B 12 or folate [25,29,30]. Anemia is also common among persons with increased MCV due to other causes [3,25,29,30], but evaluation of all possible circumstances associated with macrocytosis or anemia was beyond the scope of the HEIRS Study.…”

“…Anemia is also common among persons with increased MCV due to other causes [3,25,29,30], but evaluation of all possible circumstances associated with macrocytosis or anemia was beyond the scope of the HEIRS Study. It has been proposed that supranormal values of MCV could be used to detect hemochromatosis in white persons of western European descent who are receiving routine medical care [31].…”

Clinico-aetiologic profile of macrocytic anemias with special reference to megaloblastic anemia

“…McPhedran (1973), Davidson (1978) and Colon-Otero et al (1992) have variously described their fi ndings in patients with macrocytosis [2,3,9]. McPhedran defi ned the cause of macrocytosis in the absence of anemia in 100 consecutive patients and reported that the most common cause of macrocytic anemia was megaloblastic anemia due to vitamin B 12 and folate defi ciency [2].…”

“…The discovery, that an anemic patient's erythrocyte is abnormal in size, suggests certain diseases can be suspected or excluded on the basis of this. With the advent of electronic cell counters, the MCV has become an integral and useful feature of the red cell profi le [2,3]. The Coulter counter generates a value for the average volume of red cells, which is important for categorizing the type and cause of anemia.…”

“…Macrocytosis is seen in 1.7-3.6% of patients seeking medical care and is a common fi nding in any clinical setting, often in the absence of anemia [2,3,5]. The disorders that lead to macrocytic anemia comprises of a heterogeneous group that act through a variety of known and postulated mechanisms.…”