From the Guidelines
Trace hematuria on urinalysis (UA) can be caused by various conditions, including urinary tract infections, kidney stones, glomerulonephritis, bladder or kidney tumors, trauma, and certain medications, with the most recent and highest quality study suggesting that the evaluation should prioritize patients with risk factors for cancer and those with gross hematuria 1.
Causes of Hematuria
The causes of hematuria can be divided into nephrogenic and urogenic causes, with renal parenchymal disease being the most common benign nephrogenic cause, and urolithiasis, infection, and benign prostatic hypertrophy being common benign urogenic causes 1.
- Urinary tract infections (UTIs)
- Kidney stones
- Glomerulonephritis
- Bladder or kidney tumors
- Trauma to the urinary tract
- Menstrual contamination in women
- Certain medications like anticoagulants, aspirin, and NSAIDs
- Strenuous exercise
- Medical conditions such as polycystic kidney disease, sickle cell anemia, or benign prostatic hyperplasia in men
Evaluation and Management
The evaluation of hematuria should include a thorough history, physical examination, urinalysis, and serologic testing, with further evaluation using imaging studies or cystoscopy as needed, and the most recent study suggests that patients with gross hematuria should have a full urologic workup, while patients with microhematuria and no risk factors may not require a complete imaging workup 1.
- Patients with suspected urinary tract infection should have urine cultures performed
- Patients with suspected interstitial cystitis or benign prostatic hyperplasia should have the appropriate clinical workup before undertaking imaging
- Patients with renal parenchymal disease should undergo a concurrent nephrology evaluation
- Use of anticoagulant therapy does not alter the urologic evaluation of microhematuria
Risk Factors for Malignancy
The most common factors associated with development of a urinary malignancy include gross hematuria, male gender, age >35 years, smoking, occupational exposure to chemicals, analgesic abuse, history of urologic disease, irritative voiding symptoms, history of pelvic irradiation, chronic urinary tract infection, exposure to known carcinogenic agents or chemotherapy, and chronic indwelling foreign body 1. In summary, the evaluation and management of trace hematuria on UA should prioritize patients with risk factors for cancer and those with gross hematuria, and should include a thorough history, physical examination, urinalysis, and serologic testing, with further evaluation using imaging studies or cystoscopy as needed 1.
From the Research
Causes of Trace Hematuria on Urinalysis (UA)
- Urinary tract infections (UTIs) caused by urease-producing gram-negative organisms can lead to the formation of infection stones, which may cause trace hematuria 2
- Urinary tract obstruction, neurogenic bladder, voiding dysfunction, temporary or indwelling urinary catheters, distal renal tubular acidosis, and medullary sponge kidney are considered risk factors for developing infection stones, which can cause hematuria 2
- Metabolic stones that passively trap bacteria from coexistent UTIs can also cause hematuria 2
- The presence of microscopic hematuria detected by urine dipstick test is an important step in the diagnostic algorithm of renal colic, and a negative urinalysis for microscopic hematuria can occur in about 9-18% of patients with renal colic 3
- False-positive results for UTI can occur due to improper collection technique, contamination, or other factors, leading to abnormal urinalysis results, including trace hematuria, in disease-free women 4
Urinalysis Results
- Urinalysis is a routine screening and diagnostic tool that can be used to identify infections and diseases, including those that cause hematuria 5
- Automated urinalysis indices can be abnormal in a disease-free population, even with ideal collection technique, leading to false-positive results 4
- Urine nitrite showed a high specificity for UTI diagnosis, but other indices, such as leukocyte esterase, nitrites, white blood cells, bacteria, and epithelial cells, can be abnormal in the absence of UTI 4
- The interpretation of urinalysis results requires consideration of the clinical context and the potential for false-positive or false-negative results 6