Prediction of red cell mass from weight and height: a nomogram.

RICHARD W. PAYNE Department of Haematology, Worcester Royal Infirmary, Worcester WR5 JHN, UK The further investigation of suspected polycythaemia in patients with an elevated venous haematocrit is a not infrequent problem in haematological practice. Measurement of the actual red cell mass (ARCM) in such patients is relatively simple, using standard radioisotope dilution techniques (International Committee for Standardisation in Haematology, 1973). Interpretation of results may be less straightforward, particularly when the red cell mass is expressed in relation to total body weight; for although red cell mass is related to total body weight, it is much more closely related to lean body mass (Muldowney, 1957). Interpretation is thus less subject to error 1003 when red cell mass is expressed in relation to lean body mass (Muldowney, 1957; Hyde and Jones, 1962; Hume and Goldberg, 1964). Lean body mass is also closely related to height and weight (Hume, 1966). Thus the above studies have shown that lean body mass is closely related to (a) height and weight, and (b) red cell mass; and hence a relationship between height and weight and red cell mass can be inferred. Calculations based on the above data of Hume (1966) and Hume and Goldberg (1964) have been utilised to produce a nomogram which allows the expected normal red cell mass (ENRCM) to be predicted directly from height and weight in males and in females (Figure). This nomogram facilitates the further investigation of patients with an elevated haematocrit, since prediction of the ENRCM is very simple. Subsequent comparison of the predicted value Received for publication 20 March 1978