Polycythaemia in pyridoxin deficiency in the rat.

Severe anaemia in pyridoxin deficiency has been reported in dogs (Fouts, Helmer, Lepkovsky & Jukes, 1938; Fouts, Helmer & Lepkovsky, 1940; Borson & Mettier, 1940; McKibbin, Schaefer, Frost & Elvehjem, 194z), pigs (Wintrobe, Follis, Miller, Stein, Alcayaga, Humphreys, Suksta & Cartwright, 1943), chicks (Luckey, Briggs, Elvehjem & Hart, 1945), ducks (Hegsted & Rao, 1945) and monkeys (McCall, Waisman, Elvehjem & Jones, 1946; Poppen, Greenberg & Rinehart, 1952). In the rat, Fouts & Lepkovsky (1942) observed only a slight reduction of haemoglobin concentration, and Kornberg, Tabor & Sebrell (1945) produced a moderately severe anaemia in a small proportion of deficient rats. More recently, Carpenter & Kodicek (1948) and Gubler, Cartwright & Wintrobe (1949) found no significant reduction in haemoglobin concentration, whereas Agnew ( 1949) observed that both haemoglobin concentration and colour index were significantly reduced in rats deficient in pyridoxin. On the basis of haemoglobin values, it is generally believed that little or no anaemia occurs in pyridoxin deficiency in the rat, in marked contrast with other animals. In the course of studies of cutaneous and mucocutaneous changes in pyridoxin deficiency, which have been described elsewhere (Ramalingaswami & Sinclair, 1953), we followed the progressive changes in the blood of the rat at different stages of the deficiency and observed a significant and sustained elevation of the erythrocyte count in the deficient animals. This observation had been recorded earlier by Carpenter & Kodicek (1948) and Agnew (1949); the former also demonstrated microcytosis of the erythrocytes in this condition. A distinct increase in the erythrocyte count has been observed in the monkey during the late stages of pyridoxin deficiency and attributed by the authors to dehydration (Poppen et al. 1952). In the present study, which confirmed the occurrence of polycythaemia, observations have been made in an attempt to clarify its pathogenesis.