Hematuria is a common symptom affecting men and women of all ages. The cause is usually a benign one but serious underlying conditions like malignancies may manifest for the first time with hematuria.
Gross versus Microscopic Hematuria:
Gross hematuria is visible to the naked eye. A little as 1 ml of blood in the urine can give the urine a reddish brown color. The passage of blood clots almost always indicate a lower urinary tract pathology, however, patients with kidney cancers can occasionally present with the passage of blood clots.
Microscopic hematuria is not visible to the naked eye and is only detected under a microscope or via a dipstick examination. It is defined as 3 or more cells per high power field.
Often, menstruating women are labeled as having hematuria. However, this is because of the contamination of menstrual blood loss in the urine.
False positive dipstick examination
- Hemoglobinuria or myoglobinuria
- Alkaline PH and the presence of semen.
Causes of Reddish urine without blood or heme:
- Iron sorbitol
- Food Dyes:
- Food coloring
How to evaluate a patient with hematuria?
Always confirm the blood in urine via microscopic examination.
Menstruating women and individuals who have their urine tested after a vigorous exercise or a trauma should have a repeat urinalysis done.
Clues to the underlying diagnosis
- Fever, pyuria, and dysuria is suggestive of a urinary tract infection
- A history suggestive of a recent upper respiratory tract infection is suggestive of either IgA nephropathy, post-streptococcal glomerulonephritis, vasculitis, and antiGBM ab
- A positive family history of kidney disease may be a clue to polycystic kidney disease, sickle cell disease, and hereditary nephritis
- Unilateral flank pain radiating to the groin is suggestive of nephrolithiasis
- Symptoms of hesitancy, urgency, urinary dribbling, and a weak stream or post-micturition dribbling is suggestive of a prostatic pathology
- Recent vigorous exercise or trauma
- A systemic bleeding diathesis
- Renal tuberculosis or Schistosoma haematobium in endemic areas
How to differentiate between glomerular and non-glomerular hematuria
Signs of glomerular bleeding include:
- RBCs cast,
- Dysmorphic red blood cells, and/or
RBC casts are diagnostic of glomerular bleeding, however, their absence does not exclude a glomerular cause. Furthermore, RBCs casts may be disrupted by the process of centrifugation and casts accumulate at the edge of the coverslip.
Proteinuria due to glomerular bleeding usually exceeds 500 mg per day.
Blood clots in the urine exclude a glomerular cause. Diluted urine and the presence of urokinase in the urine prevents the formation of blood clots in the urine.
The urine dipstick may show +1 proteins in the presence of blood. However, a greater than 1+ proteinuria is rarely seen in non-glomerular diseases.
Patients with glomerular hematuria as manifested by dysmorphic RBCs, proteinuria and a rising creatinine should undergo a renal biopsy except in patients with diabetic nephropathy.
What are the risk factors for malignancy in a patient with hematuria?
The American urological association (AUA) have identified the following risk factors for malignancy in patients with microscopic hematuria:
- Male gender
- Older age (>35 years)
- Past or current history of smoking
- Occupational exposure to chemicals or dyes
- History of gross hematuria
- History f irritative voiding symptoms
- History of chronic urinary tract infection
- Exposure to cyclophosphamide
- History of radiation to the pelvis
- History f exposure to aristocholic acid
- History of chronic indwelling foreign body
- History of analgesic abuse
Causes of isolated glomerular hematuria:
- Ig A nephropathy
- Thin basement membrane disease
- Mesangioproliferative glomerulonephritis without Ig A deposits
- Alport syndrome.
Causes of Hematuria:
- Benign Renal masses (angiomyolipoma)
- Malignant renal masses (renal cell carcinoma)
- Glomerular bleeding (mentioned above)
- Structural diseases (polycystic kidney disease)
- Malignant hypertension
- Renal vein thrombosis
- Arteriovenous malformations
- Papillary necrosis
- Fibroepithelial polyp
- Malignancy (transitional cell carcinoma)
- Prostate/ Urethra:
- Benign prostatic hyperplasia
- Prostate cancer
- Prostatic procedures
- Traumatic catheterization