Haematuria may
be visible and reported by the patient (macroscopic haematuria), or invisible
and detected on dipstick testing of urine (microscopic haematuria). It
indicates bleeding from anywhere in the renal tract Microscopy shows that
normal individuals have occasional red blood cells (rbc) in the urine (up to 12
500 rbc/mL). The detection limit for dipstick testing is 15–20 000 rbc/mL,
which is sufficiently sensitive to detect all significant bleeding. However,
dipstick test are also positive in the presence of free haemoglobin
or myoglobin. Urine
microscopy (p. 461) can be valuable
in confirming
haematuria and in establishing the of bleeding . Other causes of red or dark
urine may sometimes be confused with haematuria but produce negative dipstick
tests and microscopy
. True positive
tests may occur during menstruation, infection or strenuous exercise, but
persistent haematuria requires further investigation to exclude malignancy. Glomerular
bleeding is characteristic of inflammatory, destructive or degenerative
processes that disrupt the glomerular basement membrane (GBM) to cause
microscopic or macroscopic haematuria. In glomerulonephritis, one or more other
features of the ‘nephritic syndrome’ may be present, but the full syndrome is
rare . Macroscopic (visible) haematuria is more likely to be caused by tumours
. Severe infections or renal infarction can also cause macroscopic haematuria,
usually accompanied by pain.
Investigations and management
Investigation of
haematuria whether microscopic or macroscopic, should be directed first at the
exclusion of an anatomical bleeding lesion, particularly in older patients or
others at risk of carcinoma of the bladder or other malignancy . If haematuria occurs with proteinuria or clinical features
of kidney disease , inflammatory renal disease should be considered and a renal biopsy may be
indicated. Where there are no features of significant kidney disease and malignancy has been excluded, patients with
isolated microscopic haematuria may be managed by observation alone and biopsy
is rarely warranted. Although this scenario occasionally precedes significant renal
disease (e.g. Alport’s syndrome, IgA nephropathy), it is commonly caused by the
usually benign condition of thin basement membrane disease (p. 504),
insignificant vascular malformations, renal cysts or renal stones. In ‘loin pain-haematuria’ syndrome, benign
glomerular bleeding is associated with loin pain. Management of haematuria
depends upon the cause.
