[Lights and shadows on the molecular diagnosis of hepatitis C]

The rational application of molecular biology to clinical diagnostics must take in consideration the economic demands, as the waste of sophisticated and expensive assays is of no use for the physician prescribing the assays and burdensome for the individual or the community paying them. Sometimes it is useless to apply to the molecular biology, and the information obtainable through serology answer our demands. This brief survey of the principal means available today for Hepatitis C diagnosis and monitoring, besides summarising the principles on which the different techniques are based, wants to underline the most noteworthy aspects of the different assays--from general indication to specific application to a single case--in the attempt to improve the efficacy of the test, which may be the right one at the right moment. There are qualitative and quantitative methods for viremia determination, which not always are alternative; on the contrary they must sometimes be complementary in order to obtain a complete clinical pattern. As a matter of fact the clinician should choose according to protocol susceptibility and considering what the expected viremia could be. The risk of false negatives is very dreadful for the clinician, as that of false positives (from contamination) is threatening for the laboratory, which must carry out more work than its capabilities consent. One must not misuse these diagnostic means, but they must be used correctly in order not to transform an important service into a harmful inefficiency with unpleasant consequences both for the physician and the patient.