Table 6.

Diagnosis of TBMN

Characteristic FeatureSensitivitySpecificityComments
Persistent glomerular hematuria, minimal proteinuria, normal BP, and normal renal functionHigh (80%)ModerateTBMN is the most common cause; occurs in IgA disease too but often with higher urinary red blood cell counts and (less commonly) proteinuria
Family history of hematuriaModerate (70%)HighFamily history of hematuria is also common in X-linked Alport syndrome
Generally thinned GBM without focal lamellation95%High
Collagen IV α3α4α5 network present in GBM100%ModerateSupports but does not prove the diagnosis of TBMN
α5(IV) collagen chain present in skinSupports but does not prove the diagnosis of TBMN
Hematuria segregates with COL4A3/COL4A440%High
Hematuria does not segregate with the COL4A5 locusHighHighLinkage studies require careful characterization of other family members but are possible with very few members
Single mutation in COL4A3 or COL4A480%Very high