Signs of Loss of Blood Supply to One Kidney
The primary signs of a loss of blood supply to one kidney (renal ischemia) include acute onset of flank pain, hematuria, and hypertension, often accompanied by decreased urine output. 1
Clinical Presentation
Immediate Signs and Symptoms
- Severe flank pain on the affected side - often the earliest and most prominent symptom 1, 2
- Hematuria (blood in urine) - may be gross or microscopic 2, 1
- Sudden onset hypertension or worsening of existing hypertension 3, 1
- Decreased urine output (oliguria) - though this may be less pronounced with unilateral involvement 2, 1
Laboratory Findings
- Elevated serum creatinine and blood urea nitrogen (BUN) - indicating impaired kidney function 4, 2
- Elevated lactate levels - suggesting tissue hypoxia 2, 5
- Proteinuria/albuminuria - indicating kidney damage 2, 6
- Elevated levels of kidney injury biomarkers (e.g., NGAL, KIM-1) in urine 2, 4
Imaging Findings
- IV contrast-enhanced CT with immediate and delayed images is the gold standard diagnostic test 2, 1
- Absence of contrast enhancement in the affected kidney 2
- Potential visualization of thrombus or occlusion in the renal artery 1, 2
- Delayed or absent nephrogram phase on the affected side 2, 1
Pathophysiological Signs
Vascular Complications
- Arterial contrast extravasation on imaging studies 2, 1
- Development of pseudoaneurysms or arteriovenous fistulas 2, 1
- Pulsating or expanding retroperitoneal hematoma in cases of renal pedicle avulsion 1, 2
Tissue Damage
- The renal medulla is particularly susceptible to ischemic injury due to its high metabolic demand and vulnerability to vascular congestion 6, 7
- Outer medullary region shows the earliest signs of damage due to its unique vascular architecture 6, 5
- Reperfusion injury may occur if blood flow is restored, leading to generation of reactive oxygen species and inflammatory response 7, 5
Complications and Late Signs
- Development of renovascular hypertension - may persist for up to a year after the initial event 1, 3
- Progressive azotemia (increasing creatinine) despite treatment 3, 4
- Development of urinary extravasation if collecting system is damaged 1, 2
- Potential progression to chronic kidney disease if ischemia is prolonged 4, 3
Special Considerations
- In trauma patients, renal ischemia may be part of a larger injury pattern and can be overlooked if not specifically investigated 2, 8
- Hemodynamic instability despite resuscitation in trauma patients suggests ongoing bleeding and requires immediate intervention 2
- In non-traumatic cases, sudden onset of symptoms in patients with atherosclerotic disease suggests thromboembolic etiology 3, 6
Pitfalls in Diagnosis
- Unilateral renal ischemia may not cause significant changes in overall kidney function if the contralateral kidney is healthy 2, 3
- Rises in serum creatinine may be delayed by 24-48 hours after the ischemic event 2, 4
- Standard urinalysis may be normal in early stages, requiring specific biomarkers for early detection 4, 2
- Failure to obtain both immediate and delayed phases on CT imaging may miss critical findings 2, 1