EDITOR, - Fritz H Schroder emphasises the central importance of cystoscopy in the investigation of microscopic haematuria, regarding renal biopsy as required in only a minority of patients.1 We have commented previously on the disadvantage of this approach, which is likely falsely to reassure some patients with glomerular disease, which may be progressive.2

Schroder relies on urinary red cell morphology to distinguish glomerular from non-glomerular haematuria and thus to direct the use of renal biopsy. Although both phase contrast microscopy and the alternative Coulter counter analysis of urinary red cells have been advocated enthusiastically, some authors have reported finding them unhelpful, particularly when the number of red cells is low3; the two techniques have not entered widely into British nephrological practice.4

We recently …