Nutcracker phenomenon and idiopathic IgA nephropathy

Nutcracker phenomenon and idiopathic IgA nephropathy Sir, Entrapment of the left renal vein between the aorta and the superior mesenteric artery is a documented cause of both postural proteinuria as well as intermittent gross haematuria associated with left flank pain. Idiopathic IgA nephropathy typically presents with recurrent episodes of gross haema-turia, usually following an acute febrile illness. Rarely, the disease presents as microscopic haematuria and usually mild proteinuria. We present the first case of postural pro-teinuria caused by left renal vein entrapment and recurrent gross haematuria caused by an IgA nephropathy. In an 11-year-old boy with postural proteinuria, renal ultrasonic Doppler disclosed left renal vein entrapment: the anteroposterior diameter at the hilar portion divided by that at the aortomesenteric portion was 13.3 (reference 4.0) and the peak flow velocity at the aortomesenteric portion divided by that at the hilar portion 15.1 (reference 4.0). Two years later, three episodes of acute febrile diarrhoea were followed by gross haematuria that was not associated with flank pain. The kidney biopsy showed mild diffuse mesangial proliferation and matrix expansion. The diagnosis of IgA nephropathy was made on immunofluorescence microscopy, which demonstrated isolated prominent glob-ular deposits of IgA, C3 and IgG in the mesangium. The link between left renal vein entrapment and postural proteinuria is well documented. Furthermore, both left re-nal vein entrapment and IgA nephropathy are recognized causes of recurrent gross haematuria. There are five reported patients affected with both left renal vein entrapment and idiopathic IgA nephropathy [1–4]. A 12-year-old German girl with microscopic haema-turia was found to have left renal vein entrapment and mesangial deposits of IgA [1]. Similarly, left renal vein entrapment and mesangial deposits of IgA were reported in a 9-year-old Korean girl with isolated microscopic hae-maturia and recurrent gross haematuria [2] and in a 25-year