[Diagnostic significance of antinuclear antibodies]

In three patients, women of 17, 25 and 15 years, suffering from arthralgia and in whom the existence of antinuclear antibodies (ANA) was established, the diagnosis 'systemic lupus erythematosus' was made or considered. Upon reevaluation, the ANA results could not be confirmed. The conclusion was drawn that in patients, who lack one or more clinical signs of a connective tissue disease (CTD), no indication is present for determination of ANA. Literature data indicate that the positive predictive value of ANA for the presence of CTD is 5-10%. Conversely, a negative ANA result does not rule out that CTD is present (negative predictive value: 98.5-99.3%). In addition, the question is raised if a hospital laboratory, lacking experience or routine in ANA assays could reliably perform these assays.