Merck Manual

Please confirm that you are a health care professional

honeypot link

Isolated Hematuria

By

Geetha Maddukuri

, MD, Saint Louis University

Last full review/revision Jan 2021| Content last modified Jan 2021
Click here for Patient Education
Topic Resources

Hematuria is red blood cells (RBCs) in urine, specifically > 3 RBCs per high-power field on urine sediment examination. Urine may be red, bloody, or cola-colored (gross hematuria with oxidation of blood retained in the bladder) or not visibly discolored (microscopic hematuria). Isolated hematuria is urinary RBCs without other urine abnormalities (eg, proteinuria Proteinuria Proteinuria is protein, usually albumin, in urine. High concentrations of protein cause frothy or sudsy urine. In many renal disorders, proteinuria occurs with other urinary abnormalities (eg... read more , casts).

Red urine is not always due to RBCs. Red or reddish brown discoloration may result from the following:

Pathophysiology of Isolated Hematuria

Red blood cells (RBCs) may enter urine from anywhere along the urinary tract—from the kidneys, collecting system and ureters, prostate, bladder, and urethra. In females, normal or abnormal uterine bleeding may be misdiagnosed as hematuria.

Etiology of Isolated Hematuria

Most cases involve transient microscopic hematuria that is self-limited and idiopathic. Transient microscopic hematuria is particularly common in children, present in up to 5% of their urine samples. There are numerous specific causes (see table Some Specific Causes of Hematuria Some Common Specific Causes of Hematuria Hematuria is red blood cells (RBCs) in urine, specifically > 3 RBCs per high-power field on urine sediment examination. Urine may be red, bloody, or cola-colored (gross hematuria with oxidation... read more ).

The most common specific causes differ somewhat by age, but overall the most common are

Vigorous exercise may cause transient hematuria. Cancer and prostate disease are a concern mainly in patients > 50, although younger patients with risk factors may develop cancer.

Glomerular disorders can be a cause at all ages. Glomerular disorders Overview of Glomerular Disorders The hallmark of glomerular disorders is proteinuria, which is often in the nephrotic range (≥ 3 g/day). Glomerular disorders are classified based on urine changes as those that manifest predominantly... read more may represent a primary renal disorder (acquired or hereditary) or be secondary to many causes, including infections (eg, group A beta-hemolytic streptococcal infection), connective tissue disorders and vasculitis Overview of Vasculitis Vasculitis is inflammation of blood vessels, often with ischemia, necrosis, and organ inflammation. Vasculitis can affect any blood vessel—arteries, arterioles, veins, venules, or capillaries... read more Overview of Vasculitis (eg, systemic lupus erythematosus Systemic Lupus Erythematosus (SLE) Systemic lupus erythematosus is a chronic, multisystem, inflammatory disorder of autoimmune etiology, occurring predominantly in young women. Common manifestations may include arthralgias and... read more Systemic Lupus Erythematosus (SLE) [SLE] at all ages, immunoglobulin A–associated vasculitis Immunoglobulin A–Associated Vasculitis (IgAV) Immunoglobulin A–associated vasculitis (formerly called Henoch-Schönlein purpura) is vasculitis that affects primarily small vessels. It occurs most often in children. Common manifestations... read more Immunoglobulin A–Associated Vasculitis (IgAV) [Henoch-Schönlein purpura] in children), and blood disorders (eg, mixed cryoglobulinemia, serum sickness). Worldwide, IgA nephropathy Immunoglobulin A Nephropathy Immunoglobulin A (IgA) nephropathy is deposition of IgA immune complexes in glomeruli, manifesting as slowly progressive hematuria, proteinuria, and, often, renal insufficiency. Diagnosis is... read more Immunoglobulin A Nephropathy is the most common form of glomerulonephritis. Thin basement membrane disease and mild IgA nephropathy may cause isolated hematuria; however, most other glomerular causes of hematuria are accompanied by proteinuria.

Schistosoma haematobium, a parasitic fluke that causes significant disease in Africa (and, to a lesser extent, in India and parts of the Middle East), can invade the urinary tract, causing hematuria. Schistosomiasis Schistosomiasis Schistosomiasis is infection with blood flukes of the genus Schistosoma, which are acquired transcutaneously by swimming or wading in contaminated freshwater. The organisms infect the vasculature... read more is considered only if people have spent time in endemic areas. Mycobacterium tuberculosis may also infect the lower or upper urinary tract and cause hematuria, occasionally causing urethral strictures Urethral Stricture Urethral stricture is scarring that obstructs the anterior urethral lumen. Urethral stricture can be Congenital Acquired Anything that damages the urethral epithelium or corpus spongiosum can... read more .

Table
icon

Evaluation of Isolated Hematuria

History

History of present illness includes duration of hematuria and any previous episodes. Urinary obstructive symptoms (eg, incomplete emptying, nocturia, difficulty starting or stopping) and irritative symptoms (eg, irritation, urgency, frequency, dysuria) should be noted. Patients should be asked about the presence of pain and its location and severity and whether they have vigorously exercised.

Review of systems should seek symptoms of possible causes, including joint pain and rashes (connective tissue disorder), and hearing loss or ocular manifestations (hereditary nephritis Alport Syndrome Alport syndrome is a genetically heterogeneous disorder characterized by nephritic syndrome (ie, hematuria, proteinuria, hypertension, eventual renal insufficiency) often with sensorineural... read more Alport Syndrome , also called Alport syndrome). Presence of fever, night sweats, or weight loss should also be noted.

Past medical history should include questions about any recent infections, particularly a sore throat that may indicate a group A beta-hemolytic streptococcal infection. Conditions known to cause urinary tract bleeding (particularly kidney calculi Urinary Calculi Urinary calculi are solid particles in the urinary system. They may cause pain, nausea, vomiting, hematuria, and, possibly, chills and fever due to secondary infection. Diagnosis is based on... read more , sickle cell disease Sickle Cell Disease Sickle cell disease (a hemoglobinopathy) causes a chronic hemolytic anemia occurring almost exclusively in blacks. It is caused by homozygous inheritance of genes for hemoglobin (Hb) S. Sickle-shaped... read more Sickle Cell Disease or trait, and glomerular disorders Overview of Glomerular Disorders The hallmark of glomerular disorders is proteinuria, which is often in the nephrotic range (≥ 3 g/day). Glomerular disorders are classified based on urine changes as those that manifest predominantly... read more ) should be sought. Also, conditions that predispose to a glomerular disorder, such as a connective tissue disorder (particularly systemic lupus erythematosus Systemic Lupus Erythematosus (SLE) Systemic lupus erythematosus is a chronic, multisystem, inflammatory disorder of autoimmune etiology, occurring predominantly in young women. Common manifestations may include arthralgias and... read more Systemic Lupus Erythematosus (SLE) [SLE] and rheumatoid arthritis Rheumatoid Arthritis (RA) Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease that primarily involves the joints. RA causes damage mediated by cytokines, chemokines, and metalloproteases. Characteristically... read more Rheumatoid Arthritis (RA) ), endocarditis Infective Endocarditis Infective endocarditis is infection of the endocardium, usually with bacteria (commonly, streptococci or staphylococci) or fungi. It may cause fever, heart murmurs, petechiae, anemia, embolic... read more Infective Endocarditis , shunt infections, and abdominal abscesses Intra-Abdominal Abscesses Abscesses can occur anywhere in the abdomen and retroperitoneum. They mainly occur after surgery, trauma, or conditions involving abdominal infection and inflammation, particularly when peritonitis... read more Intra-Abdominal Abscesses , should be identified. Risk factors for genitourinary (GU) cancer should be identified, including smoking (the most significant), drugs (eg, cyclophosphamide, phenacetin), and exposure to industrial chemicals (eg, nitrates, nitrilotriacetate, nitrites, trichloroethylene).

Physical examination

The abdomen should be palpated for masses; flanks should be percussed for tenderness over the kidneys. In men, a digital rectal examination should be done to check for prostate enlargement, nodules, and tenderness.

Red flags

Interpretation of findings

Clinical manifestations of the various causes overlap significantly, so urine and often blood tests are required. Depending on results, imaging tests may then be needed. However, some clinical findings provide helpful clues (see table Some Common Causes of Hematuria Some Common Specific Causes of Hematuria Hematuria is red blood cells (RBCs) in urine, specifically > 3 RBCs per high-power field on urine sediment examination. Urine may be red, bloody, or cola-colored (gross hematuria with oxidation... read more ).

On the other hand, some common findings (eg, prostate enlargement, excessive anticoagulation), although potential causes of hematuria, should not be assumed to be the cause without further evaluation.

Testing

Before testing proceeds, true hematuria should be distinguished from red urine by urinalysis. In women with vaginal bleeding, the specimen should be obtained by straight catheterization to avoid contamination by a nonurinary source of blood. Red urine without red blood cells (RBCs) suggests myoglobinuria or hemoglobinuria, porphyria Overview of Porphyrias Porphyrias are rare disorders in which hemoglobin is abnormally metabolized due to genetic or acquired deficiencies of enzymes of the heme biosynthetic pathway. These deficiencies allow heme... read more , or ingestion of certain drugs or foods. Generally, the presence of hematuria should be confirmed by testing a 2nd specimen.

Presence of casts, protein, or dysmorphic RBCs (unusually shaped, with spicules, folding, and blebs) indicates a glomerular disorder Overview of Glomerular Disorders The hallmark of glomerular disorders is proteinuria, which is often in the nephrotic range (≥ 3 g/day). Glomerular disorders are classified based on urine changes as those that manifest predominantly... read more . White blood cells or bacteria suggest an infectious etiology. However, because urinalysis shows predominantly RBCs in some patients with cystitis Cystitis Bacterial urinary tract infections (UTIs) can involve the urethra, prostate, bladder, or kidneys. Symptoms may be absent or include urinary frequency, urgency, dysuria, lower abdominal pain... read more , urine culture is usually done. A positive culture result warrants treatment with antibiotics. If hematuria resolves after treatment and no other symptoms are present, no further evaluation is required for patients < 50, especially women.

If patients < 35 (including children) have only microscopic hematuria and no urine findings suggesting a glomerular disorder, no clinical manifestations suggesting a cause, no risk factors for cancer, and an identified benign cause (eg, infection, mild trauma), they can be observed, with urinalysis repeated every 6 to 12 months. If a benign cause is not evident or hematuria is persistent, testing is indicated (1 General reference Hematuria is red blood cells (RBCs) in urine, specifically > 3 RBCs per high-power field on urine sediment examination. Urine may be red, bloody, or cola-colored (gross hematuria with oxidation... read more ), beginning with ultrasonography or CT with contrast, sometimes followed by cystoscopy.

Patients < 50 with gross hematuria or unexplained systemic symptoms require ultrasonography or CT of the abdomen and pelvis.

If urine or clinical findings suggest a glomerular disorder, renal function is evaluated by measuring blood urea nitrogen, serum creatinine, and electrolytes; doing a urinalysis; and periodically determining the urine protein/creatinine ratio. Further evaluation of a glomerular disorder may require serologic tests, kidney biopsy Renal biopsy Biopsy of the urinary tract requires a trained specialist (nephrologist, urologist, or interventional radiologist). Indications for diagnostic biopsy include unexplained nephritic or nephrotic... read more , or both.

General reference

Treatment of Isolated Hematuria

Treatment is directed at the cause.

Key Points

  • Red urine should be differentiated from true hematuria (red blood cells in urine).

  • Urinalysis and urine sediment examination help differentiate glomerular from nonglomerular causes.

  • Risk of serious disease increases with aging and with duration and degree of hematuria.

  • Cystoscopy and imaging tests are usually needed for patients > 35 or for younger patients with systemic symptoms or risk factors for cancer.

Click here for Patient Education
NOTE: This is the Professional Version. CONSUMERS: Click here for the Consumer Version
Professionals also read
Test your knowledge
Testicular Torsion
Testicular torsion is a serious condition due to rotation of the testis and consequent strangulation of the blood supply. Torsion is most common in males between the ages of 12 and 18 years and is uncommon in men older than 30 years. When a patient presents with testicular torsion, which of the following is the most immediate symptom?
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
 

Also of Interest

 
TOP