Loin Pain Haematuria Syndrome (LPHS) is a rare clinical condition characterized by chronic or recurrent “loin” (flank) pain accompanied by haematuria (blood in the urine).
Because the pain is often severe and the cause is frequently difficult to identify, LPHS is one of the most challenging conditions in nephrology and urology.
The symptoms vary significantly from person to person but generally fall into two categories:
1. The Pain (Loin Pain)
Location: Pain occurs in the “loin” area—the part of the back below the ribs and above the pelvis where the kidneys are located. It can affect one side (unilateral) or both (bilateral).
Nature: It may be a continuous dull ache or intermittent, sharp attacks of severe pain.
2. The Blood (Haematuria)
Visible (Macrohaematuria): The urine appears red, pink, or cola-colored. Occasional blood clots may be present.
Non-Visible (Microhaematuria): The blood is only detectable via a urinary dipstick test or laboratory microscopy.
Medical professionals often divide LPHS into two distinct categories to guide treatment:
Type 1: Identified Pathological Cause
In Type 1, a specific medical condition is causing the symptoms. Common causes include:
IgA Nephropathy: An autoimmune condition where antibodies build up in the kidney, causing inflammation.
Thin Basement Membrane Nephropathy: A genetic condition where the filtering membrane is abnormally thin.
Nutcracker Syndrome: Occurs when the left renal vein is compressed between the abdominal aorta and the superior mesenteric artery.
Post-Urinary Tract Infection (UTI): Chronic pain can persist following a severe kidney infection (pyelonephritis), even after bacteria have cleared.
Type 2: “Classic” LPHS (Diagnosis of Exclusion)
Classic LPHS is diagnosed when the patient has severe pain and blood in the urine, but all standard tests (scans and biopsies) come back normal.
Key Fact: Classic LPHS is a “diagnosis of exclusion.” It is only diagnosed after kidney stones, tumours, and infections have been ruled out.
Kidney Function: Classic LPHS does not cause kidney failure or long-term damage to kidney function.
Demographics: It most commonly affects women (approx. 70% of cases), with an average onset age of 30.
Hormonal Links: Some women find pain worsens during the menstrual cycle or while taking oral contraceptives.
Blood Testing: Blood tests for kidney function (Creatinine & eGFR) are usually normal.
Biopsy Results: A kidney biopsy is typically normal, though it may show microscopic red blood cells.
Pain Intensity: The pain can be incapacitating, requiring specialized pain management.
Diagnostic Challenge: Up to 23% of patients with acute kidney pain have no identifiable abnormality on a CT scan.
Vascular Theories: Some believe pain is caused by spasms in the small blood vessels (vasospasms).
Link to Stones: Roughly 50% of patients have a previous history of nephrolithiasis (stones).
Persistence: The condition can last for years but often improves or disappears over time.
Because the cause of Classic LPHS is unknown, treatment focuses on symptom management.
Medical Management
Blood Pressure Meds: ACE inhibitors are often prescribed to reduce pressure within the kidney.
Anticoagulants: Low-dose aspirin or warfarin is occasionally used to improve blood flow.
Pain Specialists: A multi-disciplinary approach involving a nephrologist, GP, and pain psychologist is often the most effective route.
The Surgical Perspective
Surgery is generally not recommended. Procedures like “denervation” or kidney removal (nephrectomy) are rarely successful long-term; pain often returns on the opposite side.
LPHS is a complex condition. While the pain is severe, it does not lead to kidney failure. Management requires patience and a strong relationship with a medical team.
EdRen (Edinburgh Renal Unit): Specialist information on LPHS.
National Kidney Federation (NKF): Support for rare renal syndromes.
Rare Diseases (NORD): Global database for LPHS research.
Reviewed by Dr. Oshini Shivakumar (Renal Registrar)
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