A 28-month-old female presented with diarrhea, vomiting, recurrent aphthous stomatitis, and growth failure. She was born  at 33 weeks’ gestation with a birth weight of 1700 g and had failed to achieve catch-up growth over the subsequent 28 months. Her past history was notable for recurrent aphthous stomatitis, repeated upper respiratory tract infections, and two episodes of vomiting and diarrhea at 10 and 25 months of age. There was no significant medical family history, and the parents were not consanguineous.

On physical examination, her weight was 8.7 kg and height was 79.5 cm. The most prominent finding was marked pallor, accompanied by a grade 2 systolic murmur. Laboratory investigations showed hemoglobin 7.3 g/dL, hematocrit 22%, white blood cell count 5120/mm³, mean corpuscular volume (MCV) 96 fL, and platelet count 76,200/mm³. Peripheral blood smear demonstrated hypersegmented neutrophils and macrocytic red blood cells with significant anisopoikilocytosis. Urinalysis demonstrated a ++ albumin in urine with protein/creatinine (P/Cr) ratio of 1.5. Liver and renal function tests, serum electrolytes, and markers of hemolysis (LDH, bilirubin, serum proteins, and reticulocyte count) were within normal limits. Bone marrow aspiration revealed megaloblastic erythroid hyperplasia with characteristic nuclear–cytoplasmic dissociation.

 Urinary N-acetyl-β-D-glucosaminidase (NAG) and β₂-microglobulin were elevated, suggesting a tubular component to the proteinuria. However, urine protein electrophoresis revealed a glomerular pattern, with albumin and transferrin comprising 96.5% and 3.5% of total urinary proteins, respectively. Renal ultrasonography demonstrated normal anatomy with no evidence of urinary tract malformations, and the patient had no prior history of urinary tract infections.

A diagnostic test was done.