Urinary platelet factor four (Pf4) levels in mesangial IgA glomerulonephritis and thin basement membrane disease.

The aim of this study was to assess the significance of platelet factor four (Pf4) excretion in the urine of patients with mesangial IgA glomerulonephritis (IgAGN) and thin basement membrane disease (TBMD), and ascertain if Pf4 is a useful parameter to distinguish these diseases. The concentration of Pf4 in urine (Pf4) was determined by an enzyme linked immunoabsorbent assay (ELISA) in patients with IgAGN (n = 80), TBMD (n = 37), membranous nephropathy (MN) (n = 12), minimal change nephrotic syndrome (MCNS) (n = 3), crescentic glomerulonephritis (CGN) (n = 6) and in healthy controls (n = 20), and then compared with urinalysis and renal function. An immunoperoxidase method was used to examine urine sediments for the presence of platelets. Urinary Pf4 was detected in 35 out of 80 patients with IgAGN (median 0.15, range 0.07-2.5 ng/ml, n = 35), in only 2 out of 37 patients with TBMD (p less than 0.005), in all patients with CGN and in no patients from MN, MCNS or control groups. A positive correlation between urinary Pf4 levels and red blood cell counts was observed in patients with IgAGN (r = 0.876, p less than 0.001), but not in TBMD. Pf4 did not correlate with proteinuria or plasma creatinine in either group. Platelets were detected in urine in 10 out of 15 patients with IgAGN but in only 1 out of 9 patients with TBMD. Urinary red blood cell counts in all of these 24 patients were over 100,000/ml.(ABSTRACT TRUNCATED AT 250 WORDS)