Table 2: Background serology.

Assay Abnormal result
N (total found)
Normal reference range Value taken as abnormal result

Rheumatoid factor 48 (74)<15 IU/mL >14 IU/mL
ANA 5 (76)Nil >1 : 160
ENA4 (65)Nil+
Mixed cryoglobulinemia 7 (82) Nil +
C3 low4 (81)0.75–1.65 g/L <0.75 g/L
C4 low14 (80) 0.14–0.54 g/L <0.14 g/L