LOIN PAIN HEMATURIA SYNDROME-ASSOCIATED WITH THIN GLOMERULAR-BASEMENT-MEMBRANE DISEASE AND HEMORRHAGE INTO RENAL TUBULES

Loin pain-hematuria (LPH) syndrome is a poorly understood disorder in which the patients, mainly young women, experience unexplained severe chronic unilateral or bilateral flank pain associated with gross and/o r microscopic hematuria. By contrast, thin glomerular basement membran e (GBM) disease is generally thought to be a benign disorder, affectin g males and females equally, in which the major manifestation is asymp tomatic microscopic hematuria. Herein we describe seven patients (6 fe males, 1 male) in whom thin GBM appeared to be the cause of the LPH sy ndrome. The gross hematuria in these patients could be attributed to t hin GBM disease because the renal biopsy demonstrated red cells in ren al tubules (indicating glomerular hematuria) and the only glomerular a bnormality present was thin GBM. In addition, the other causes of gros s hematuria were excluded by appropriate testing. The flank pain in th ese patients might also have been the result of their thin GBM disease . This is suggested by renal biopsy findings of multiple renal tubules filled with red cells, apparently occluding the tubules. We suggest t hat occlusion of a relatively small fraction of renal tubules could ca use renal pain if back-leak of glomerular filtrate occurred that was o f sufficient magnitude to expand renal parenchymal volume and stretch the renal capsule. Preliminary observations suggest that treatment wit h the angiotensin converting enzyme (ACE) inhibitor enalapril importan tly reduces the frequency and severity of the episodes of gross hematu ria and flank pain in most patients. ACE inhibition might decrease glo merular hemorrhage in patients with thin GBM by decreasing glomerular hydrostatic pressure. We conclude that (1) Thin GBM disease can be the cause of gross hematuria, apparently as a result of rupture of thin G BM. (2) Rupture of thin GBM resulting in hemorrhage into renal tubules may be the cause of the flank pain and gross hematuria in some patien ts with the LPH syndrome.