The Renal Fellow Network did a nice pocket review of Loin Pain Hematuria Syndrome recently. However they left off an important diagnosis which also presents with hematuria and unilateral pain, Nut Cracker Syndrome. This refers to impingement of the left renal vein between the aorta and superior mesenteric artery.
These patients usually come to the nephrology office with a history of mysterious kidney stones which have been difficult to visualize.
In Nut Cracker Syndrome the pain is always on the left side.
Nice review with imaging studies are found in this NDT article from 1995.
(a) MRI revealed a dilated left renal vein (black arrows) after passing between the aorta (A) and superior mesenteric artery (white arrowhead).
(b) MRA showed that the diameter of the left renal vein (black arrow) was larger in the left part adjacent to the aorta (A) compared with the right adjacent part. A prominent left ovarian vein (white arrow), implicating formation of a collateral circulation, was also noted. IVC = inferior vena cava.
(c) Digital subtraction MRA found the impingement of the left renal vein (LRV) between the aorta (A) and superior mesenteric artery (white arrowhead).
The aptly named Nutcracker Syndrome sounds quite painful.
Do you know why these patients get hematuria?
The model in my head is the same explanation for hematuria with renal vein thrombosis, back pressure from the blocked renal vein this may result in rupture of the thin walled vein into the renal calyx causing intermittent gross or microscopic hematuria.