DIAGNOSTIC APPLICATIONS OF THE BLOOD-COUNT 247 



Rheumatism.— Except in the very mildest cases there is leuco- 

 cytosis, and, according to Turk, Ewing, and others, when there 

 are more than 20,000 there is almost certainly some complication, 

 such as endocarditis, pericarditis, pneumonia, or hyperpyrexia. I 

 believe this may be taken as a safe general rule, though excep- 

 tions do occur. 



Turk believes that a clue to prognosis may be got from the 

 percentages of eosinophiles present ; with a proportion above the 

 normal the case is likely to be a mild one. 



Tuberculosis.— There is usually marked anaemia of the 

 secondary type, but in cases with sweating and diarrhoea this 

 may be masked by the concentration of the blood ; an apparent 

 improvement in this respect may in reality be a bad sign. The 

 leucocytes are usually normal, though the lymphocytes may be 

 rather high. 



Where secondary septic infection takes place — e.g., in a vomica 

 — the blood is that of sepsis; there is a variable leucocytosis, 

 excess of polynuclears, and advancing anaemia. 



The blood-count is not of much value in the diagnosis of 

 tubercle ; it is of some value in prognosis. Increase in the poly- 

 nuclears and in the grade of anaemia are bad signs in phthisis. 



There are one or two precautions to be noted in special cases. 

 In tuberculous empyema there is frequently a secondary infection, 

 and the presence of a leucocytosis does not show that the disease 

 is not tuberculous ; the same thing applies to tuberculous abscesses 

 in other parts, including the joints. 



Tuberculous meningitis appears to offer the most marked 

 exception to the rule, that uncomplicated tubercle does not cause 

 leucocytosis. Here there is often moderate leucocytosis, and 

 according to Horder it may reach 25,000. I have several times 

 met with 20,000 or thereabouts. Tuberculous pleurisy is usually 

 without marked leucocytosis, but occasionally the figure may reach 

 18,000 to 20,000. 



Syphilis. — There is usually progressive secondary anaemia with 

 moderate leucocytosis (12,000 to 16,000), due mainly to increase of 

 lymphocytes, often of the large type, but the figures are too 

 inconstant to be of much value in diagnosis. 



Purpura Hemorrhagica. ^ There is naturally advancing 

 anaemia, which may be associated with a low or normal colour- 

 index. In the most common type of case, in which the prognosis 

 is relatively good, there is also the usual slight polynuclear l&uco- 



