Apolipoprotein B subspecies in chylomicrons isolated from a patient with chyluria.

The diagnosis and the clinical course of a 17-year-old white male with chyluria are reported. Cloudy, milky urine appeared spontaneously, in the absence of edema or any signs or symptoms of parasitic infection. Pedal lymphangiography demonstrated the presence of a lymphatic renal fistula, and digital subtraction angiography showed aneurysmal dilatation of the aorta at the level of the renal arteries. This case provided an opportunity to ascertain which of the forms of apolipoprotein B were present in lymph chylomicrons. Apolipoprotein B is needed for chylomicron secretion. It exists in several forms--B-100, B-74, B-48, and B-26. After a meal consisting of fat, chylomicrons in which apolipoprotein B-48 was virtually the only apolipoprotein B present appeared in the urine, while apolipoprotein B-100 was the only apolipoprotein B present in the plasma very low-density lipoproteins. Chyluria disappeared two weeks after institution of a low-fat diet. This case illustrates an interesting, rare cause of chyluria. Because of the presence of chyluria, it was also demonstrated that chylomicrons in which apolipoprotein B-48 is virtually the only apolipoprotein B present are a physiologically normal product of the intestine.