Glomerular basement membrane thickness - a comparison of two methods of measurement in patients with unexplained haematuria.

BACKGROUND: Thin glomerular basement membranes may be an important cause of microscopic haematuria. Unfortunately measurements are often not made because of the complicated methods currently employed.
METHODS: A simplified method of measurement of glomerular basement membrane thickness, involving only 16 selected measurements on a single glomerulus, was compared with the accepted, but time-consuming, orthogonal intercept technique. Thirty-one needle biopsies from patients with renal haematuria unexplained by conventional histology and immunofluorescence were studied. Measurements were made on the same ultrathin sections.
RESULTS: The new method was found to give much lower values (mean (SD) 202+/-51 versus 282+/-52 nm) with limits of agreement of -131 to -30 nm compared with the orthogonal intercept method. The coefficient of repeatability was 39 nm for the orthogonal intercept method and 56 nm for the new method. However, using two glomeruli the new method had limits of agreement of -120 to -41 nm with a coefficient of repeatability of 38 nm.
CONCLUSIONS: Provided two glomeruli are measured the new technique is sufficiently accurate for the diagnosis of thin membrane nephrology, in appropriate cases, and is much simpler and cheaper than the orthogonal intercept method.