2l8 CLINICAL BACTERIOLOGY AND HEMATOLOGY 



When you find a case with a high colour-index, it should 

 immediately raise a suspicion of pernicious anaemia. Look 

 again at the preparation in which you have counted the reds in 

 the Thoma-Zeiss hsemocytometer, and look for unusually large 

 corpuscles (megalocytes), which, according to Ewing, should form 

 35 per cent, of all corpuscles, or the diagnosis is to be made with 

 caution. Then count the leucocytes in the same preparation. 

 Leucopenia is very characteristic ; if the number exceeds 6,000, 

 pernicious anaemia is unlikely, unless inflammatory complications 

 are present. Then make a differential count on a stained film, 

 looking out for megalohlasts and normoblasts as you do so ; in 

 pernicious anaemia there is almost always a relative lymphocytosis, 

 and the diagnosis is unlikely with the lymphocytes much below 

 40 per cent. If you have not yet seen a megaloblast, continue to 

 search for them, as they are usually present in pernicious anaemia 

 of moderate severity, and comparatively rare in other conditions, 

 except in children. The significance of the discovery of a single 

 megaloblast will depend on the other findings ; if these point to 

 pernicious anaemia, the megaloblast may be taken as clinching 

 the diagnosis, but if they are not of this nature its importance is 

 much less. Do not exclude pernicious anaemia because no 

 megaloblasts are found. According to Ehrlich and others they 

 always exceed the normoblasts in numbers, but this is not a safe 

 guide, as in some cases you may find normoblasts alone on some 

 occasions, and megaloblasts and normoblasts in differing pro- 

 portions on others. Polychromatophil and granular degeneration 

 and poikilocytosis are common in advanced stages of the disease, 

 but the diagnosis ought to have been made before their appearance. 



The diagnosis from secondary anamia rests on the high colour- 

 index, the leucopenia, lymphocytosis, nucleated corpuscles and 

 megalocytes, and is usually easy. Anaemia associated with 

 intestinal parasites may resemble idiopathic pernicious anaemia in 

 every respect except in that the former is accompanied by 

 eosinophilia. In pernicious anaemia the eosinophils are usually 

 low, and if they exceed 4 per cent, the faeces should be searched 

 for the ova of parasites (especially ankylostoma, bothriocephalus 

 and oxyuris). The anaemia of carcinoma of the stomach and other 

 gastric diseases may closely resemble pernicious anaemia, but in 

 most cases there is a high leucocyte count, with increase of 

 polynuclears and diminution of lymphocytes. 



Chlorosis. — Here there is a moderate reduction of the red 



