Hematuria

Red blood cells (RBCs) are not present in the urine of 95% of healthy individuals. If urine appears pink or red, false negatives should be ruled out (as discussed under urinalysis).

 

Microscopic hematuria is defined as >2 RBCs per high powered field in centrifuged urine sediment. It is seen in up to 13% of the asymptomatic population, and is almost always incidental (Mohr et al, 1986).

 

Exercise-induced hematuria is common and can be both microscopic and macroscopic. It is seen in both contact and non contact sports. There are a variety of explanations, including ischemic damage, efferent arteriole vasoconstriction, or bladder trauma (Abarbanel et al, 1990). RBCs are seen in the urine, in contrast with rhabdomyolysis and march hemoglobinuria.

 

Hematuria can also be the first sign of intrinsic renal disease or malignancy. Blood can come from the kidney, GU tract, or urethra. More serious causes of hematuria are diverse, and include the following:

renal causes

urological causes

systemic causes

 

Initial Investigations for hematuria include a thorough history and physical exam, with special attention paid to:

 

Further investigations, in ascending order:

 

Prognosis for asymptomatic microhematuria, without malignancy or evidence of renal disease, is very good. Good control of blood pressure (<130/80 mmHg) and reduction of (micro)proteinuria is very important to maintain kidney function. ACE inhibitors or ARBs are useful in addressing both. Further follow-up is required, with regular urinalysis, and monitoring of blood pressure and renal function.

 

Extrarenal: blood clots in urine, or 3 glass test

 

Resources and References

Abarbanel J et al. 1990. Sports Hematuria. Journal of Urology. 143:887-890.

Mohr DN et al. 1986. Asymptomatic microhematuria and urologic disease. A population-based study. JAMA. 256:224-229.