Coexisting nutcracker phenomenon and superior mesenteric artery syndrome in a patient with IgA nephropathy

Rationale: Nutcracker and superior mesenteric artery (SMA) syndrome share the same pathogenesis, but the simultaneous occurrence of both diseases is quite rare. A combination of the nutcracker syndrome and IgA nephropathy has previously been reported. Herein, we report what we believe is the first case of coexisting nutcracker and SMA syndrome in a patient with IgA nephropathy. Patient concerns: A 15-year-old Chinese boy who was diagnosed with IgA nephropathy at 8 years of age presented with gross hematuria, fatigue, anorexia, nausea, and recurrent abdominal distension for 1 week without any obvious evidence of preceding infection. Laboratory data showed macroscopic hematuria, heavy proteinuria, and relatively normal renal function. Doppler ultrasonography and upper gastrointestinal gastrografin study were performed, respectively. Since his renal function deteriorated after admission, repeated renal biopsy was performed. Diagnoses: IgA nephropathy with nutcracker phenomenon and SMA syndrome. Intervention: Immunosuppressive therapy combined with conservative therapy for superior mesenteric artery syndrome. Outcomes: One month later, his abdomen symptoms such as anorexia and abdominal distension eased a lot with body weight increase of about 3 kg. After 6 months of follow-up, his body weight increased to 57 kg, serum creatinine decreased to 63 μmol/L, and urine microscopy showed 75.5 RBC/high-power field with 0.3 g urine protein per day. Lessons: Although the association between vascular compression and IgA nephropathy (IgAN) has not been elucidated yet, combination of nutcracker syndrome and SMA syndrome should be considered in patients with IgAN. The combination may increase the complexity of the disease, and renal biopsy should not be hesitated for differential diagnosis.