title: Glomerular basement membrane thickness in children: a stereologic assessment.
abstract: BACKGROUND
  Stereologic methods have emerged as the technique of choice in assessing glomerular basement membrane (GBM) thickness, following conceptual modeling comparing the stereologic technique of harmonic mean of the orthogonal intercept estimation (Th) with the model based method of arithmetic mean estimation (ATH), with no direct comparison undertaken. We undertook to establish the gold standard for GBM estimation and use this technique to establish a range for GBM thickness in children.
  
  
  METHODS
  Intra-observer and inter-glomerular variation was estimated in 34 cases with (presumed) normal GBM thickness, using Th, ATH and a rapid direct measurement technique, with intra-observer variation measured in 35 cases with GBM attenuation. A total of 34,011 measurements were undertaken to establish a range for Th in children on 212 biopsies from 199 patients (127 male) demonstrating minimal change nephropathy (N = 153), focal segmental glomerulosclerosis (24), no abnormality (24), and acute tubular necrosis (8), which were used as surrogates for normals.
  
  
  RESULTS
  Th demonstrated less variation than ATH in both the normal and attenuated groups. GBM thickness increased throughout childhood, from 194 +/- 6.5 nm (mean +/- SE) at one year to 297 +/- 6.0 nm at 11 years, with a reduced rate of increase after age 11 years.
  
  
  CONCLUSIONS
  Stereologic methods are superior to model based techniques in estimating GBM thickness and should be regarded as the technique of choice in this area. GBM thickness was observed to increase during childhood with no gender effect demonstrable as a main effect or interaction.
authors.affiliation: Renal Unit, Department of Pathology, Royal Hospital for Sick Children, Dalnair Street, Glasgow G3 8SJ, Scotland, United Kingdom. i.ramage@clinmed.gla.uk
authors.forename: Ian J
authors.initials: IJ
authors.lastname: Ramage
authors.forename: Allan G
authors.initials: AG
authors.lastname: Howatson
authors.forename: John H
authors.initials: JH
authors.lastname: McColl
authors.forename: Heather
authors.initials: H
authors.lastname: Maxwell
authors.forename: Anna V
authors.initials: AV
authors.lastname: Murphy
authors.forename: T James
authors.initials: TJ
authors.lastname: Beattie
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D001485:Basement Membrane / Q000473:pathology / Q000648:ultrastructure; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D007674:Kidney Diseases / Q000473:pathology*; D007678:Kidney Glomerulus / Q000473:pathology* / Q000648:ultrastructure*; D008297:Male; D008854:Microscopy, Electron / Q000379:methods* / Q000592:standards; D015203:Reproducibility of Results; D012737:Sex Factors