Loin pain hematuria syndrome is a rare disorder in which patients suffer episodes of severe unilateral or bilateral flank pain with microscopic or gross hematuria in the absence of renal pathology.
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Epidemiology
Approximately 70% of patients are young females with a peak incidence in the third decade of life 1. It is rare, affecting approximately 0.01% of the population 2.
Clinical presentation
Episodes of pain may last from minutes to hours or, even months, and may occur in variable frequency from one episode per year to much more frequently 1. Hematuria usually accompanies the pain but can be separate. Blood counts, renal function, coagulation testing and urinary protein are usually normal 1,2.
Diagnostic criteria
The diagnosis of loin pain hematuria syndrome is one of exclusion 2.
glomerular (e.g. glomerulonephritis) and non-glomerular sources of bleeding (e.g. urinary tract infection, urolithiasis, renal cell carcinoma) must be excluded first
episodes of pain must last longer than 6 months
in at least 2 episodes of loin pain imaging (e.g. CT or ultrasound) must be obtained and demonstrate an absence of urolithiasis or urinary tract obstruction
hematuria with greater than five red blood cells per high power field must also be present
Pathology
The cause of loin pain hematuria syndrome is unknown 2. Although a number of potential processes have been suggested including: glomerular basement membrane structural abnormalities, psychiatric elements, IgA nephritis, coagulopathies, calcium deposition within the renal tubules, and complement activation in renal arterioles 2,3.
Radiographic features
The main role of imaging in loin pain hematuria syndrome is to exclude other causes of pain and hematuria. Ideally the imaging should be performed during an episode of pain, as per the diagnostic criteria 2.
Treatment and prognosis
Management is directed at providing pain relief during symptomatic episodes which is often challenging 2. Spontaneous resolution of the condition has been described in about half of patient within 3-5 years after the onset of symptoms 2. The disorder is not thought to increase patient's long-term mortality 2. Occasionally a renal autotransplant is performed to relieve the symptoms 5.
History and etymology
The condition was first described in 1967 by PJ Little and colleagues 4.
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