Loin pain hematuria syndrome (LPHS) is the combination of debilitating unilateral or bilateral flank pain and microscopic or macroscopic amounts of blood in the urine that is otherwise unexplained.Loin pain-hematuria syndrome (LPHS) is a poorly defined disorder characterized by recurrent or persistent loin (flank) pain and hematuria that appears to represent glomerular bleeding. Most patients present with both manifestations, but some present with loin pain or hematuria alone. Pain episodes are rarely associated with low-grade fever and dysuria, but urinary tract infection is not present. The major causes of flank pain and hematuria, such as nephrolithiasis and blood clot, are typically not present. Renal arteriography may suggest focally impaired cortical perfusion, while renal biopsy may show interstitial fibrosis and arterial sclerosis.The pain is typically severe, and narcotic therapy is often prescribed as a way to manage chronic pain. Sleep can be difficult because the supine position increases pressure on the flank. The onset of pain is often associated with nausea and vomiting, making pain management by oral opiates complicated. Cause
The cause of LPHS is not known. One theory proposes that it is caused by a thin glomerular basement membrane and red blood cell (RBC) renal tubular congestion that leads to swelling of the kidney and distension of the renal fascia resulting in pain.Researchers have hypothesized that the syndrome may be due to blood vessel diseases of the kidney, spasms of the kidney vessels, or other bleeding disorders (coagulopathy). The hematuria in LPHS may be due to an abnormal (thick or thin) glomerular basement membrane.
Relation to thin basement membrane disease
A thin glomerular basement membrane, as in thin basement membrane disease, is proposed to be the characteristic finding on renal biopsy, but not part of the syndrome definition. Differential diagnosis
Kidney stones
Nutcracker syndrome
IgA nephropathy
Cancer of the genitourinary tract
Chronic pelvic pain
Endometriosis
Pyelonephritis

Treatment
The treatment of LPHS varies considerably from centre to centre. As the condition is rare and poorly understood, a widely adopted standard of care is not existent.Treatment of loin pain-hematuria syndrome (LPHS) typically consists of pain management. Narcotics or oral opioids may be prescribed to help control pain. Patients with severe pain may need high-dose opioids daily or almost daily. Occasionally, people with LPHS require hospitalization for intravenous opioid therapy and control of nausea. Other treatments may include denervation, autotransplantation, renal neurectomy, or nephrectomy. Unfortunately symptoms often recur following these procedures. Limited evidence suggests that drugs that inhibit angiotensin may reduce the frequency and severity of episodes of loin pain and gross hematuria.Pain management with opiate and non-opiate analgesia is common.