We determined serum laminin P₁ concentrations in normal subjects and diabetic patients in relation to nephropathy, in which glomerular basement membranes are known to be accumulated and thickened. RIA-Laminin P₁ Kit (Hoechst Co.) was used for the determination of Laminin P₁, a component of lamina lucida of basement membranes.
Serum laminin P1 concentrations in patients with nephropathy, as diagnosed by persistent proteinuria, were significantly higher than those in normals or patients without nephropathy. Moreover, significant relationships were found between serum laminin P₁ and daily urinary protein.
Thus, serum laminin P₁ can be used as an indicator to signify the progression of diabetic nephropathy or microangiopathy.