Urinary high density lipoprotein--a possible marker for glomerular proteinuria

High--resolution two--dimension electrophoresis technique for protein with silver staining was used to characterise urinary high density lipoprotein (HDL)--apolipoproteins. Sequential ultracentrufugation method was used to isolate urinary lipoprotein particles of the same density as serum HDL. Immunostaining of electroblotted proteins further confirmed the presence of HDL--Apos in urine. HDL--Apolipoprotein A--1, A--11 and C were identified in urine of normal subjects, diabetic patients and patients with biopsy proven glomerular proteinuria. An in-house ELISA method was used to quantify urinary HDL--Apo A--1. Selectivity indices were also determined. A high degree of association was found between selectivity index and urinary HDL--Apo A--1 (r = 0.87) and also between HFL--APO A--1 loss/24 h and total protein loss/24 h (r = 0.91). This appear to indicate that HDL loss in urine was a function of glomerular selectivity. Urinary HDL--Apo A--1 levels were significantly raised in the patients with glomerular proteinuria (p less than 0.01). HDL--Apo A--1 levels appear to be a marker for glomerular proteinuria. Consistent with glomerular proteinuria serum lipids and protein loss were significantly higher in patients with glomerular proteinuria (p less than 0.001) but HDL--Cholesterol was lower (p less than 0.001).