Loin Pain Hematuria Syndrome

Loin pain hematuria syndrome is a rare disease with a prevalence of ∼0.012%. The most prominent clinical features include periods of severe intermittent or persistent unilateral or bilateral loin pain accompanied by either microscopic or gross hematuria. Patients with loin pain hematuria syndrome initially present with hematuria, flank pain, or most often both hematuria and flank pain. Kidney biopsies from patients with loin pain hematuria typically reveal only minor pathologic abnormalities. Further, loin pain hematuria syndrome is not associated with loss of kidney function or urinary tract infections. Loin pain hematuria syndrome-associated hematuria and pain are postulated to be linked to vascular disease of the kidney, coagulopathy, renal vasospasm with microinfarction, hypersensitivity, complement activation on arterioles, venocalyceal fistula, abnormal ureteral peristalsis, and intratubular deposition of calcium or uric acid microcrystals. Many patients with loin pain hematuria syndrome also meet criteria for a somatoform disorder, and analgesic medications, including narcotics, commonly are used to treat loin pain hematuria syndrome-associated pain. Interventional treatments include renal denervation, kidney autotransplantation, and nephrectomy; however, these methods should be used only as a last resort when less invasive measures have been tried unsuccessfully. In this review article, we discuss and critique current clinical practices related to loin pain hematuria syndrome pathophysiology, diagnosis, treatment, and prognosis.