[The changing spectrum of fever of unknown origin: trends and comparison with previous series at the Salvador Zubirán National Institute of Nutrition].

We reviewed 400 medical records of patients admitted because of fever at the National Institute of Nutrition Salvador Zubirán between January 1, 1988 to December 31, 1992. Patient characteristics, diagnostic methods, final diagnosis and patient progress were analyzed, comparing these data with the previous series of the institute. We found 77 cases of fever of unknown origin (FUO), 47 males and 30 females, between 14 to 87 years of age. The final diagnosis encountered were: infections (40%), neoplasias (23%), collagen diseases (13%), and other diagnosis (8%). Sixteen percent of the cases remained without a final diagnosis. The most frequent infections were HIV infection (19%), tuberculosis (19%) and endocarditis (13%). The most common neoplasia was lymphoma (55.6%), with 90% of Hodgkin's disease. SLE was the most common autoimmune disease found. The methods to establish a final diagnosis were: biopsies (52%), serology (17%), cultures (12%), image (11%), and clinical (8%). Final diagnosis by serology tests increased from 2 to 17% in comparison with previous reports. Eight laparotomies were done, which is a less frequent practice than previously (10 vs 35%). We saw only one case of amebic hepatic abscess and had no cases of malaria and salmonellosis as final diagnosis of FUO; HIV infection was found to be a new major cause of FUO.