Analyse statistique, sur 20 mois, des types de cryoglobulines et de l’isotypie des immunoglobulines impliquées

Summary The analysis of cryoglobulins (CG) constitutes a test of which the rate of prescription increased in a significant way these last years. We realized a statistical study over a period of approximately 20 months. There were 728 requests for this examination, that is 1.25 requests a day among which 192 were positive for CG. The requests concerned 448 patients with a ratio of 1.6. The rate of positive results is 25% among which 13% have a dosage greater than 20 mg leading to the characterization of the CG by immuno-fixation (IFE). This rate of positivity seems to us to testify of the relevance of the prescription of this analysis. The majority of the concentrations of CG (70.3%) are comprised between 20 and 50 mg, 16.6% are between 51 and 100 mg/L, 11.6% between 101 and 500 mg/L, 1.5% have a concentration superior to 500 mg/L. The frequency according to the type of CG is: type III: 48.3%, type IIa: 31.7%, type I: 11.7%, type IIb 8.3%. The frequency of the isotype of the implied immunoglobulins (Ig) is: IgM 90%, IgG 45%, IgA 17%. These results teach us that this test is well prescribed, however, some physicians ask for it another two or three consecutive days. An information must be made to aim towards a single request by patient as far as this analysis is mastered well, in particular as regards the respect for the performing conditions before analytics at 37 °C and the isolation step at +4 °C. This study allows us to notice that the frequency of the CG involving a monoclonal Ig (type I and IIa: 43.4%) is practically the same that that of the polyclonal mixed CG type III (48.3%). Our study confirms that IgM is present in 90% of the CG cases.