LAUSR

A 5-year-old girl with a background of DiGeorge syndrome presented with glomerulonephritis and nephrotic syndrome. She was diagnosed with an interrupted aortic arch that was corrected surgically at 3 days of life. At the age of 3 months, she underwent a Ross procedure involving pulmonary autograft replacement of the aortic valve, and a conduit (a homograft) replacing the pulmonary valve. As an infant, she required calcium replacements until the age of 2 years. An immunologic workup was normal. She presented with a 2-week history of facial and limb swelling with exacerbation over that time period. There was no history of any recent febrile illness and she was not exposed to medications other than inhalers for asthma nor had any dietary changes. On admission, her weight was 21 kg (4 kg over her recent weight). On physical examination, she was apyrexial, with elevated blood pressure of 137/72 and a normal heart rate of 89 beats per minute. Cardiovascular examination demonstrated a known pan-systolic murmur. She had significant facial and periorbital edema as well as bilateral lower limb pitting edema and mild ascites. On initial workup, her complete blood count demonstrated significant microcytic anemia with a hemoglobin of 6.7 g/dL and MCV 66 fL and markers of iron deficiency (iron indices, iron 5 mcg/dl, transferrin saturation 1.7%). Leukocytes were elevated at 17,200/uL, of which 66% were neutrophils. Platelets were within the normal range (219,000/ uL). Blood electrolytes were normal and renal function was within normal limits, with creatinine 0.47 mg/dL and BUN 13 mg/dL. Blood albumin was low (2.8 g/dL). CRP (Creactive protein) was elevated at 7.89 mg/dL (normal range 0–0.5 mg/dL). Complement studies demonstrated low C3 and C4 levels (45 mg/dL and 9 mg/dL respectively). Serum lipid profile was within normal limits (triglycerides 66 mg/dL; cholesterol 92 mg/dL). Urine evaluation revealed microscopic hematuria with 5 to 10 red blood cells/hpf, and significant proteinuria with an elevated urine total protein to creatinine ratio of 3.32 mg/mg (normal range < 0.2). Anti-streptolysin O titers were insignificant and ANA was normal. The patient was diagnosed with hypocomplementemic glomerulonephritis with nephrotic syndrome, iron deficiency anemia, and elevated inflammatory markers. She was treated with antihypertensive medications and received a blood transfusion. Due to her background of congenital cardiac disease, an ophthalmology consultation was requested. Eye examination revealed retinal hemorrhages with pale centers. The answer to this question can be found at http://dx.doi.org/10.1007/ s00467-019-04243-5.