l8o CLINICAL BACTERIOLOGY AND HEMATOLOGY 



say, the first week of treatment, a good prognosis may be given, 

 although there are no other signs of improvement, and some idea 

 as to the time necessary to effect a complete cure may be obtained. 



2. Apart from an ordinary aneemia, the estimation of the haemo- 

 globin may give an important clue as to the presence or absence 

 of other diseases. For instance, in severe sepsis there is usually 

 a very marked and rapid fall in the amount of hasmoglobin, due to 

 the destruction of the red corpuscles by the toxin of the infective 

 organisms. This is especially valuable in that it occurs in severe 

 infections in which the leucocytes often do not undergo character- 

 istic alterations (p. 222). Thus, if an increasing anaemia is found 

 in a patient during the puerperium, it points strongly to puerperal 

 fever, and the prognosis is bad, assuming, of course, that there is 

 no haemorrhage or other cause of anaemia. 



In interpreting the results of this examination you must re- 

 member that when there is severe diarrhoea, sweating, polyuria, 

 or any other symptom in which there is a great loss of water, the 

 blood may be temporarily concentrated, and the amount of haemo- 

 globin (and of red corpuscles, but not of leucocytes, or not to a 

 proportionate extent) may appear to rise. Discount this in giving 

 a good prognosis in septic conditions from the increase in the 

 haemoglobin. A similar concentration may occur from mitral 

 disease or venous stasis from any cause. 



3. A fall in the amount of haemoglobin in a case watched from 

 day to day indicates haemorrhage, and is occasionally valuable in 

 the differential diagnosis of internal haemorrhage — e.g., in cases of 

 ruptured tubal gestation. 



4. In malaria there is a fall in the amount of haemoglobin, very 

 rapid and sudden in the early stages, and often marked, though 

 less rapid, in the later ones. The fall is often to an extent only 

 equalled in acute sepsis. This may be of much diagnostic value. 

 In typhoid fever and in the other diseases for which malaria may 

 be mistaken the anaemia is usually developed much more slowly, 

 if at all. 



5. Considerable help is afforded in the diagnosis of syphilis by 

 Justus's test, which is based on the fact that in the primary and 

 secondary stages of that disease the red corpuscles are abnormally 

 easily destroyed by the action of mercury, provided that that drug 

 has not been previously administered. The test is also of value 

 in the diagnosis of hereditary syphilis. 



To use it, estimate the haemoglobin as accurately as possible, 



