[Crozet protocol: does a lipid-rich meal interfere with cryoglobulinemia assay?]

Cryoglobulins are serum immunoglobulins that precipitate reversibly at low temperature. It is important to determine their presence, because they can be responsible for severe complications. They can also reveal underlying conditions, in particular hepatitis C and haematological diseases. Laboratory investigations of cryoglobulins are problematic and require adherence to strict preanalytical conditions. We decided to determine wether a patient really needs to be in a fasting state when a blood sample is taken. In practice, this requirement is difficult for us to meet, because of our large patient population (consultations in a teaching Hospital). We therefore devised a protocol, called the Crozet protocol based on the assay of cryoglobulinemia in healthy volunteers, before and after a meal rich in lipids. Ten patients were tested. Cryoglobulinemia assays were performed according to the technique of Hartree. Lipid profiles were measured on Modular P (Roche Diagnostics). Cryoglobulinemia assay does not seem to be unduly affected by a meal rich in lipids, in particular in triglycerides. Hence the patient does not necessarily have to be on an empty stomach at blood sampling. This study allowed us to modify our threshold of significance (from 15 to 30 microg/mL), which confirmed our view of the physiological character of a low cryoglobulinemia level. Studies involving a greater number of healthy subjects are needed to accurately establish a new threshold and to confirm our findings.