The delayed appearance of an antinuclear factor and the diagnosis of systemic lupus erythematosus in glomerulonephritis.

In 11 patients who presented with apparently idiopathic glomerular disease the antinuclear factor (ANF) was absent initially but was eventually detected during observation extending over 6 years. In 4 patients a diagnosis of systemic lupus erythematosus (SLE) has now been made and the disease treated. Of the remaining 7, 2 had conditions known to be associated with a positive ANF, and in 4, drug therapy induced the ANF. Clinical features, complement studies and measurement of anti-DNA antibody were of value in distinguishing those patients with SLE from the others.