Loin pain hematuria syndrome

Overview

Loin pain hematuria syndrome (LPHS) is a rare and poorly understood medical condition characterized by chronic, severe flank (loin) pain and the presence of blood in the urine (hematuria), without an identifiable cause such as infection, kidney stones, or tumors. LPHS primarily affects young women but can occur in both sexes and at various ages. It can be debilitating, significantly impairing the quality of life due to persistent pain and the challenge of managing symptoms.

Causes

The exact cause of LPHS remains unknown, and it is often considered a diagnosis of exclusion. The condition is divided into two types based on underlying factors:

• Type 1 LPHS – associated with identifiable urological causes such as kidney stones, thin basement membrane disease, or nutcracker syndrome (compression of the renal vein)

• Type 2 LPHS – idiopathic, with no detectable structural or vascular abnormalities

Potential contributing mechanisms include:

• Microscopic vascular abnormalities in the kidney

• Renal tubular dysfunction or sensitivity

• Ureteral or renal capsule nerve irritation

• Psychological stress or somatic pain syndromes (in debated cases)

Symptoms

The hallmark symptoms of LPHS include:

• Severe, chronic loin pain – typically unilateral but can be bilateral; often described as sharp, stabbing, or throbbing

• Hematuria – may be microscopic (only seen on urinalysis) or visible as dark or red-colored urine

• Episodes of pain exacerbation – triggered by physical activity, stress, or for unknown reasons

• Nausea or vomiting – often accompanying intense pain episodes

• Fatigue and reduced activity levels

• Depression or anxiety – due to chronic pain and impact on daily functioning

Diagnosis

LPHS is diagnosed by ruling out all other possible causes of flank pain and hematuria. A thorough diagnostic process may include:

• Urinalysis and urine microscopy – to confirm hematuria and rule out infection

• Imaging studies – such as ultrasound, CT scan, or MRI to exclude kidney stones, tumors, or anatomical abnormalities

• Cystoscopy – to examine the bladder and ureters for lesions or structural defects

• Renal biopsy – in some cases, to assess for glomerular disease or thin basement membrane disease

• Renal venography or Doppler ultrasound – to evaluate for nutcracker syndrome

When all other causes are excluded and the characteristic symptoms are present, a diagnosis of LPHS may be made.

Treatment

Treatment of LPHS is challenging and often requires a multidisciplinary approach focused on symptom relief. Options include:

• Pain management – including nonsteroidal anti-inflammatory drugs (NSAIDs), opioids, or nerve pain medications (e.g., gabapentin, amitriptyline)

• Regional nerve blocks – such as renal nerve ablation or epidural infusions for temporary pain relief

• Physical therapy – to maintain mobility and reduce muscle tension

• Psychological support – including cognitive behavioral therapy (CBT) for coping with chronic pain

• Angioplasty or surgery – if an underlying vascular cause such as nutcracker syndrome is identified

• Autotransplantation – in severe, refractory cases, surgical relocation of the kidney has shown mixed success

Prognosis

The prognosis for individuals with LPHS is variable. Some may experience spontaneous improvement over time, while others endure chronic, disabling pain for many years. Although the condition is not life-threatening, it can severely affect quality of life, employment, and mental health. Early recognition, supportive care, and pain management are essential for improving outcomes. Research is ongoing to better understand the condition and develop more targeted therapies.