ig6 clinical bacteriology and hematology 



Clinical Applications. 



The clinical applications of the leucocyte count are so wide 

 that it is hardly possible to summarize them here ; it is more 

 convenient to refer to each special case separately under the 

 heading of the blood-count as a whole. For example, in dealing 

 with typhoid fever the leucocyte count is explained and the points 

 on which a diagnosis is framed are given, which, in a case in 

 which there is a doubt as to the diagnosis between this con- 

 dition and pneumonia, may be referred to in conjunction with the 

 account of the latter. 



It will be convenient, however, to give a list of the usual 

 counts met with in certain diseases, classified under five headings 

 in respect of the number of leucocytes to be expected in them. 

 But these figures must always be considered with reference to 

 the fuller accounts of the diseases in question. 



I. Enormous Leucocytosis (100,000 to 1,000,000). — Such 

 figures are practically only met with in myelogenous or lymphatic 

 leucocythsemia, though suppuration, pneumonia, and hooping- 

 cough may very rarely approximate thereto. 



II. High Leucocytosis (20,000 to 100,000). — Suppuration in 

 all situations and of all kinds, the degree of the leucocytosis being 

 a measure of the virulence of the organism and the resisting 

 power of the patient. 



Pneumonia, in which the same facts hold. 



Hooping-cough. 



Meningitis, especially suppurative meningitis, whether cerebro- 

 spinal, pneumococcic, etc. In tuberculous meningitis there may 

 be as many as 25,000 leucocytes. 



Pleurisy, especially empyema. A leucocyte count of 20,000 

 does not exclude tuberculous pleurisy, but tells strongly against it. 



Scarlet fever. 



Diphtheria. 



Hemorrhage. — After a very severe haemorrhage, whether internal 

 {e.g., rupture, extrauterine gestation) or external [e.g., from 

 gastric ulcer), figures over 20,000 are occasionally seen, but 

 usually rule lower (12,000 to 15,000). The number usually falls 

 in a few days. 



Similar figures are seen immediately hefore death, especially if 

 the death is lingering, and very high figures are occasionally seen. 

 It is sometimes of value in prognosis. 



