creation date: 2025-10-02 17:17
tags: Workups
Hematuria
Background
Hematuria is defined as the presence of blood in the urine.
Gross hematuria refers to blood in the urine that is visible to the naked eye. Note that menstrual bleeding/clotting can be mistaken (false positive) for gross hematuria.
Microscopic hematuria refers to blood that is only detectable by urine sediment by microscopy. This is typically defined as ≥3 RBC/high-power-field on microscopy.
Pathophysiology
Hematuria may result from structural alterations due to injury, infection, or mass anywhere in the genitourinary tract.
Anticoagulation does not cause hematuria itself but may exacerbates symptoms. The pathophysiology depends on the source/etiology of the blood.
In cases of glomerular bleeding, the integrity of the renal glomerular basement membrane, mesangium, microvascular endothelium may be damaged. This results in dysmorphic RBCs and presence of RBC casts. Damage to the glomerulus can also result in proteinuria.
In cases of non-glomerular bleed, nephro- and urolithiasis, certain drugs, neoplasms, catheterization, and other causes may cause erosion or damage to the urothelial surface on the urinary tract can lead to hematuria. In comparison to glomerular, non-glomerular causes result in uniform RBCs and often the presence of clots.
Differential Diagnosis
The differential diagnoses are divided by glomerular causes:
- IgA nephropathy
- Thin basement membrane disease (benign familial hematuria)
- Alport syndrome
- Post-infectious (post-steptococcal) glomerulonephritis
- Lupus nephritis
- Polycystic kidney disease
And non-glomerular causes (which can be divided to upper and lower urinary tract):
- Urinary tract infections
- Neoplasm
- Urinary tract stones
- Benign prostatic hyperplasia
- Trauma/instrumentation
- Strenuous exercise
- Foreign bodies
A crude mnenomic can be used (TINTS):
- Trauma
- Infection
- Nephrologic
- Tumour
- Stone
Initial Evaluation
History
A targeted history may identify potential causes for hematuria.
History of gross hematuria:
- Colour and appearance of urine (smokey brown suggests glomerular vs. red/pink suggests non-glomerular)
- Number and frequency of episode
- Presence and absence of clots (presence almost always suggests nonglomerular cause)
- Point of urination where gross hematuria is noted
- Beginning of urination suggests urethral source
- Throughout voiding can be anywhere throughout the urinary tract
- Terminal hematuria suggests bladder neck or prostatic urethra
- Blood noticed as discharge between voiding while urine appears clear can suggest urethral meatus or anterior urethra
Associated symptoms may include:
- Unilateral flank pain that can radiate to the groin (usually suggests obstruction)
- Dysuria with or without fever (suggests urinary tract infections)
- Lower urinary tract symptoms (suggests BPH)
- Recent upper respiratory infection or symptoms
- Systemic symptoms (suggests possible systemic condition with glomerular disease)
Transient hematuria may be associated with recent events such as:
- Menses
- Vigorous exercise
- Acute trauma
- Recent instrumentation
A general assessment of:
- Risk factors of bladder and kidney cancer
- Comorbid health conditions such as sickle cell disease, bleeding disorders, kidney stones
- Medications which may cause hematuria (eg. cyclophosphamide, analgesics, NSAIDs)
Physical Exam
Assessment should be guided by clinical history but generally include:
- Blood pressure measurement for new or worsening hypertension
- Edema assessment
- Abdominal exam for tenderness
- Skin examination (for systemic disease)
- Genitourinary examination with an additional rectal exam for prostate palpation
Investigations
Urinalysis:
- Signs of UTI (eg. positive leukocyte esterase and/or nitrite), confirming with urine culture
- Presence of proteinuria (≥1+ on dipstick), quantification with spot urine protein-to-creatinine ratio or urine albumin-to-creatinine ratio
Basic metabolic panel:
- Kidney function (serum creatinine and eGFR)
Imaging:
- Ultrasound of kidneys and bladder may detect masses, calculi, and signs of obstruction (hydronephrosis) - primarily for upper urinary tract
- Cystoscopy (endoscopic visualization of internal aspect of urethra and bladder) - for lower urinary tract
- CT urography - CT abdo pelvis without and with IV contrast
- Magnetic resonance urography
Other investigations may be indicated as well:
- Kidney biopsy
- Urine cytology and biomarker (not routine)