How do you approach hypocomplementemia in Sjogren’s without features of lymphoma?   

Low C3 and/or C4 support immune activity. Therefore, I look at all domains that SjD can potentially affect for further clues. Low complements in SjD are associated with systemic disease activity (Ramos-Casals et al., PMID 24162151). Low C4 may suggest a more severe disease (Pavlakis et al., PMID 223...

To add on to @Basanti Mukerji and @Nancy L. Carteron: I view using C3 and C4 (low levels) as potential disease monitoring metrics. When I first see a patient, I measure C3, C4, anti-dsDNA, cryoglobulins, immunoglobulins, ESR, CRP, WBC, absolute lymph/neutrophils, Hb, platelets, AST, ALT, alkphos, e...

I would also check for an Immunoglobulin panel and see if this person has any spikes in protein or not.