title: False-positive treponemal serology in patients with diabetes mellitus.
abstract: In sera from 476 diabetic outpatients, positive reaction in the Fluorescent Treponemal Antibody-Absorption (FTA-Abs) test, a commonly used serological test for syphilis, was found in 36 of the patients. None of 100 healthy control subjects were positive in the FTA-Abs test. Additional treponemal and nontreponemal tests confirmed the diagnosis of syphilis in only three of the diabetic patients. In 10 of the 36 patients, the positive FTA-Abs reactivity appeared to be due to cross-reactivity between the treponemal antigen and Borrelia burgdorferi, which causes Lyme borreliosis. In the remaining 23 patients (5%), no other explanation for a false-positive FTA-Abs reactivity was found besides diabetes. Diabetic patients with false-positive FTA-Abs reactivity had similar degree of long-term metabolic control and prevalence of islet cell antibodies (ICA) as well as late diabetic complications as FTA-Abs negative diabetic patients, matched regarding to sex, age, type, and duration of diabetes. In conclusion, false-positive FTA-Abs reactivity is not rare in diabetic patients. The reason for this phenomenon is unknown, but could be a sign of autoimmunity of its own. Hence, in diabetic patients with FTA-Abs test indicating syphilis, the diagnosis must be verified with a combination of other tests.
authors.affiliation: Department of Clinical Bacteriology, Stockholm County Council Central Microbiological Laboratory, Sweden.
authors.forename: A
authors.initials: A
authors.lastname: Brauner
authors.forename: B
authors.initials: B
authors.lastname: Carlsson
authors.forename: G
authors.initials: G
authors.lastname: Sundkvist
authors.forename: C G
authors.initials: CG
authors.lastname: Ostenson
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001782:Blood Donors; D002648:Child; D002675:Child, Preschool; D003429:Cross Reactions; D003920:Diabetes Mellitus; D003928:Diabetic Nephropathies; D003929:Diabetic Neuropathies; D003930:Diabetic Retinopathy; D004797:Enzyme-Linked Immunosorbent Assay; D005189:False Positive Reactions; D005260:Female; D016508:Fluorescent Treponemal Antibody-Absorption Test; D006801:Humans; D008193:Lyme Disease / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D012737:Sex Factors; D013588:Syphilis Serodiagnosis