Hematuria is defined as the presence of blood in the urine. Depending upon the type and amount of blood; hematuria can be clinically classified as:
- Gross hematuria: Frank bleeding or presence of visible blood in the urine.
- Microscopic hematuria: Urine is generally clear and blood is only visible on the microscopic examination.
According to a new study reported in the peer reviewed American Family Physician journal (1), investigators described microscopic hematuria as the presence of 3 or more red blood cells per high-power field of microscope.
Symptoms of Microscopic Hematuria
Microscopic hematuria is generally asymptomatic. In other words, most cases are silent and are diagnosed incidentally on the routine urological investigation (or workup for other indications). It is imperative to mention that the prevalence of microscopic hematuria in general population is fairly high. Study reported in Journal of Urology (2) suggested that approximately 10 -20% of all adult male and females (post-menopausal) experience microscopic hematuria.
Causes of Microscopic Hematuria
Microscopic hematuria is most frequently a result of mild to moderate dysfunction of urinary system. In addition, any organic or benign condition of renal tubules (that are responsible for the filtration of your blood) can also present with microscopic hematuria. Following are some primary causes:
- Urinary tract infection: Infections involving urinary tract can present with microscopic hematuria. Bacterial invasion of urethra or bladder is perhaps the most common cause of UTI in immunocompetent adults. The classic presentation is painful and burning micturition, fever, urgency to urinate and foul smelling or strong-smelled urine.
- Kidney infections: The bacterial invasion of the kidneys, either from the blood stream or from the infected urethra or bladder can also cause the inflammation of kidney; thereby presenting with classic features of UTI but with more severe fever and flank pain.
- Kidney or bladder calculi: Recurrent episodes of UTI or passage of highly concentrated urine can aggravate the risk of calculi formation (hard stones) either in the kidney, ureters or in the bladder. These stones are the result of precipitation of minerals/ urinary salts and are generally symptomless unless they become very large and/or obstructing the urinary pathway. The symptoms of complicated or impacted calculi are; moderate to severe intermittent/episodic pain along with microscopic as well as gross hematuria.
- Enlarged prostate: Prostate gland, situated just inferior and posterior to the urinary bladder is responsible for making the fluid part of semen in the males. With progressive aging, the prostatic tissue undergo hypertrophic changes; thereby obstructing the urinary outflow from the urethra. This causes painful and urgent need to urinate, blood in urine and post void dribbling of urine.
- Disorders of glomeruli and nephrons: Glomerular inflammation (such as glomerulonephritis and glomerulonephrotic syndrome causes gross as well as microscopic hematuria). The causes include, IgA nephropathy, viral or streptococcal invagination, dehydrations, diabetes and persistent hypertension.
- Drugs and strenuous exercise: A few anticancer drugs, such as cyclophosphamides, as well as antibiotics like Penicillin and a variety of anticoagulant drugs also causes the blood to escape in the urine. Microscopic hematuria is also reported during strenuous exercise and physical activity.
Risk factors: Following are some risk factors that are usually implicated in the setting of microscopic hematuria:
- Age: Adults over the age of 50 years are more vulnerable to develop gross as well as microscopic hematuria.
- Gender: Females are more likely to develop microscopic hematuria due to higher chances of developing an infection than males.
- Post infectious state: Kidney inflammation following a bacterial or viral infection in children can lead to gross as well as microscopic hematuria.
- Family history: Positive family history of stones or kidney disease can aggravate the risk of developing asymptomatic hematuria.
- Drugs: Individuals with chronic intake of aspirin, NSAID’s, penicillin and anticancer drugs are more prone to microscopic hematuria.
- Strenuous exercise: Athletes are more prone to asymptomatic hematuria, as discussed earlier.
The best way to reduce and stop hematuria is to diagnose and treat the underlying cause. It is important to understand that hematuria is not a disease per –se; instead it is a symptom of an underlying ailment; therefore there is no treatment to address hematuria alone. Healthcare providers believes that minimizing the risk of infections in the urinary tract, controlling the diabetes and hypertension (if present), properly hydrating the body as required and avoiding the use of hematuria producing drugs can limit and prevent hematuria to a greater extent.
2. Messing EM, Young TB, Hunt VB, Emoto SE, Wehbie JM. The significance of asymptomatic microhematuria in men 50 or more years old: findings of a home screening study using urinary dip-sticks. J Urol. 1987;137:919–22.
3. Woolhandler S, Pels RJ, Bor DH, Himmelstein DU, Lawrence RS. Dipstick urinalysis screening of asymptomatic adults for urinary tract disorders. I. Hematuria and proteinuria. JAMA. 1989;262:1214–9.