Construction of a dictionary of laboratory tests mapped to LOINC at AP-HP.

We report on the ongoing process implemented at Assistance Publique-Hôpitaux de Paris (AP-HP), the largest hospital system in Europe, to build a common reference for laboratory tests in French with LOINC mappings. At the time of writing, it contained 24,000 tests, covering all fields of biology, in use in 19 AP-HP hospitals, 30% of which had a mapping to LOINC with a peak of over 60% in biochemistry.