Cryoglobulinaemia and cryofibrinogenaemia in IgA nephropathy: a follow-up study.

Sera and plasmas from 50 patients with IgA nephropathy (IgA-NP) have been investigated for the presence of cryoglobulin (CG) and cryofibrinogen (CF), respectively, 2-5 cryoprotein determinations being made for each patient. CG was transiently found in 20 of 50 patients (40%), but in none of 20 healthy blood donors, whereas CF was found in 37 of 50 patients (74%) and in 4 of 20 healthy blood donors. The cryoprecipitates were of single and mixed component types. All but 2 of the patients with CF had haematuria. Nearly all of them had histories of long exposure to the cold as manual workers at the onset or recognition of their disease. There was no clinical remission during a 2-to-5-year follow-up if cryoproteinaemia persisted. A certain correlation was detected between the composition of the CP and the renal immunohistological findings. It is suggested that renal deposition of circulating CF or local formation of CF might be responsible for the tubulo-interstitial fibrocellular changes, which are of prognostic importance.