A four year old child develops steroid-sensitive nephrotic syndrome. Renal biopsy studies demonstrate normal appearing glomeruli by light microscopy and fusion of foot processes by electron microscopy. Which of the following proteins would be present in the urine in the highest concentration?

Severe, persistent, proteinuria is required to produce nephrotic syndrome. The renal histology described is that of minimal change disease, which produces a proteinuria that is relatively selective for albumin. Ceruloplasmin is a copper-binding normal serum protein that could be spilled into the urine in many types of glomerulonephritis that cause nonselective proteinuria. IgA can also be spilled into urine in non-selective proteinuria. Both kappa and lambda light chains are freely filtered at the glomerulus, but are usually present in only tril amounts in patients who do not have multiple myeloma or related diseases. Ref: Wyatt C., Butterwoh IV J.F., Moos P.J., Mackey D.C., Brown T.G. (2008). Chapter 16. Pathology of the Kidney and Bladder. In C. Wyatt, J.F. Butterwoh IV, P.J. Moos, D.C. Mackey, T.G. Brown (Eds), Pathology: The Big Picture.