Microscopic haematuriaBMJ 1994; 309 doi: https://doi.org/10.1136/bmj.309.6947.70 (Published 09 July 1994) Cite this as: BMJ 1994;309:70
- Fritz H Schroder
Gross haematuria is obvious to the patient and is usually followed up, appropriately, by a complete urological work up. The much commoner microscopic haematuria, however, may not always receive the attention that it deserves. Dealing with this symptom adequately in the general practitioner's surgery requires a substantial body of knowledge. Recent developments warrant a re-examination of this topic.
Microscopic haematuria is rare before the age of 50 (occurring in fewer than one in 100 people of this age); after 50 the prevalence rises sharply and varies from 2% to 18% 1 2 (with some of this variation explained by different definitions). The commonly used dipstick test gives a yes or no answer to the question of whether microscopic haematuria is present and semiquantitative information at the same time. Comparing its results with those of standard microscopic evaluation of urinary sediments, one representative study found a sensitivity of 100% and a specificity of 60%.3 The relatively high frequency of false positive results of dipstick tests may be due to the technique's detection of normal numbers of red cells (1-2×1012/1 urine). The consensus is that if the result of a dipstick test is positive then the urinary sediment should be examined; if the result of a dipstick test is negative no further investigation is needed.
The figure gives an algorithm of …