A 27-year-old man consults his family physician because of
the recent onset of edema. He has no other relevant history and the physical
examination is remarkable only for significant pitting edema in the lower
extremities. His blood pressure is 135/80. The blood and urine tests reveal a BUN
of 15 mg/dL, serum creatinine of 0.9 mg/dL. The serum albumin is 1.7 g/dL
(normal = 3.5 to 5 g/dL), plasma glucose is 92 mg/dL. Urinalysis shows 4+
albumin and trace blood. The sediment shows oval fat bodies, occasional hyaline
casts, rare red cells. The albumin to creatinine ratio is 10.8.
The most likely diagnosis is
–A.) Idiopathic focal segmental glomerulosclerosis
–B.) Diabetic nephropathy
–C.) Membranoproliferative glomerulonephritis
–D.) Membranous glomerulopathy
–E.) Minimal change disease
______
Answer for GN Quiz Sep 23, 2011: D- Cast Nephropathy
The photomicrograph shows dilated tubules, each containing an eosinophilic hyaline cast, with characteristic
fractures and surrounding giant cells. The interstitium shows
infiltration with lymphomononuclear cells. Overproduction of
light chains results in an overwhelming of the capacity of the proximal tubule to reabsorb these
light chains. The filtered light chains and immunoglobulins then bind Tamm-Horsfall
glycoprotein (secreted in the medullary thick ascending limb of the loop of Henle)
and the result is cast formation and obstruction in the distal nephron.
