From the Guidelines
Hematuria in renal injury is primarily caused by damage to the renal parenchyma or the urinary tract, resulting in the presence of red blood cells in the urine.
Causes of Hematuria
- Renal parenchymal disease: The most common benign cause of hematuria, which can be due to various conditions such as glomerulonephritis, glomerulonephropathy, acute tubular necrosis, and acute kidney injury 1.
- Trauma: Blunt or penetrating trauma to the kidney can cause hematuria, with the severity of the injury correlating with the degree of hematuria 1.
- Urogenic causes: Conditions such as urolithiasis, infection, and benign prostatic hypertrophy can also cause hematuria 1.
Evaluation of Hematuria
The evaluation of hematuria depends on the clinical scenario, including the suspected etiology and the presence of other symptoms such as pain or trauma 1.
- Imaging evaluation: Ultrasound and CT scans are commonly used to assess hematuria in children, although other imaging modalities may be appropriate in certain instances 1.
- Laboratory tests: Urinalysis, blood urea nitrogen test, serum creatinine test, and complete blood count with platelets may be performed to evaluate the cause of hematuria 1.
Management of Hematuria
The management of hematuria depends on the underlying cause and may involve medical or surgical treatment.
- Benign causes: Patients with benign causes of hematuria, such as vigorous exercise or infection, may not require further evaluation or treatment 1.
- Traumatic causes: Patients with traumatic causes of hematuria may require imaging evaluation and potentially surgical intervention 1. In summary, hematuria in renal injury can be caused by various factors, including renal parenchymal disease, trauma, and urogenic causes. The evaluation and management of hematuria depend on the clinical scenario and the underlying cause, and may involve imaging evaluation, laboratory tests, and medical or surgical treatment.
From the Research
Causes of Hematuria in Renal Injury
The presence of red blood cells (RBCs) in urine, known as hematuria, can be caused by various factors related to renal injury. Some of the possible causes include:
- Glomerular filtration barrier dysfunction or damage, which may allow RBCs to escape from the glomerular capillary into the urinary space 2
- Acute interstitial nephritis, which can cause RBCs to appear in the urine, along with red blood cell casts and acute tubular injury 3
- Glomerular hematuria, which may be classified as microhematuria or macrohematuria, and can promote acute kidney injury (AKI) and impair renal function 4
- Kidney stone formation, which can trigger severe glomerular bleeding and macroscopic hematuria, leading to acute tubular damage and AKI 5
- Immunoglobulin A (IgA) nephropathy, which can cause macroscopic hematuria-associated AKI, characterized by intratubular obstruction by RBC casts and acute tubular necrosis, as well as renal hemosiderosis 6
Mechanisms of Hematuria-Induced Renal Injury
The mechanisms by which hematuria contributes to renal injury are not fully understood, but may involve:
- Cytotoxic effects of oxidative stress induced by hemoglobin, heme, or iron released from RBCs 2, 4
- Direct tubular cell injury, oxidative stress, and pro-inflammatory cytokine production caused by hemoglobin, heme, or iron released from RBCs 4, 6
- Acute tubular necrosis and renal hemosiderosis, which can occur in the absence of obvious obstructive RBC casts 6