Loin pain-hematuria syndrome (LPHS) is a rare, poorly defined kidney disorder characterized by persistent or recurrent loin (flank) pain and hematuria for at least 6 months, in the absence of urinary tract infection or obstruction. Signs and symptoms include nausea, vomiting, severe unilateral or bilateral flank pain, and microscopic or gross hematuria. Glomerular basement membrane abnormalities may play a role in the pathogenesis of hematuria in LPHS.

Treatment includes avoidance of pain-inducing activities, pain management (often opioids), surgical renal denervation, and renal autotransplantation.

Although the pathophysiology is still unknown, LPHS does not lead to chronic kidney failure.

This is a clinical diagnosis and one of exclusion. Three conditions should be met:

• Nonglomerular causes of recurrent pain and hematuria first need to be excluded: obstructing nephrolithiasis, urinary tract infection, renal cell carcinoma, autosomal dominant polycystic kidney disease, recurrent renal thromboembolism, endometriosis, and nutcracker syndrome (left renal vein entrapment between the aorta and the superior mesenteric artery).
• Hematuria is present in nearly all urinalyses.
• Pain is consistent with diagnosis (severe, frequently recurrent for 6 months or more, localized to the costovertebral angle, and worsened by percussion).