Rituximab Left Them Both Hypogammaglobulinemic: One Answer Isn't Enough
Two patients on rituximab for different immunologic diseases both develop secondary hypogammaglobulinemia with recurrent infections. Whether to start immunoglobulin replacement and hold future dosing turns out to depend entirely on whether the disease that required the drug is still active.
Denise O., 47, has worked as a labor-and-delivery nurse for over twenty years, a job she loves specifically for the unpredictability of every shift, which made it especially hard when eosinophilic granulomatosis with polyangiitis — asthma, sinus disease, and eventually biopsy-confirmed vasculitic nerve involvement in her left foot — forced her onto disability leave three years ago. Mepolizumab controlled her eosinophil count but not her vasculitis symptoms, and rituximab, started eighteen months ago as a second-line agent for the ANCA-associated component of her disease, brought her nerve symptoms and sinus disease under control well enough that she has been back on the floor part-time for the past five months. She has no other chronic diagnoses and had no history of recurrent infection at all before starting rituximab.
Routine labs ahead of her next rituximab dose show an IgG of 380 mg/dL, down from a normal baseline before treatment began, and she has had two sinus infections and one episode of pneumonia in the past four months — more than her baseline pattern before rituximab. Barmettler et al., 2018, JAMA Network Open, found that many patients on rituximab are neither screened nor treated for hypogammaglobulinemia despite a documented excess infection risk once it develops, exactly the gap her team caught by checking her IgG proactively rather than only after a second severe infection forced the question. Her vasculitis, by contrast, remains genuinely active — her most recent nerve conduction studies still show incomplete recovery, and her rheumatologist considers her at real risk of relapse if rituximab is stopped now, a relapse that in this disease has historically meant progressive nerve damage and, in more severe cases, pulmonary hemorrhage.
Her vasculitis is still active — incomplete nerve recovery, and real relapse risk if we stop rituximab now. I don't want to hold her next dose. What I do want is immunoglobulin replacement started alongside it, since Barmettler and colleagues found many rituximab patients simply aren't screened or treated for this at all despite a documented excess infection risk once it's present.
Agreed on starting replacement — an IgG of 380 with two recent infections already meets any reasonable threshold for that regardless of what happens with her rituximab schedule. Where I don’t follow you is treating replacement as fully neutralizing the risk so the dosing question closes. It restores IgG; it does not restore the B-cell compartment rituximab is depleting, and she has already had a pneumonia at 380. My addition is to reassess her IgG before every future dose rather than when a third infection forces the question, since Barmettler’s own finding was that under-screening, not under-treatment, is the pattern that lets this go unaddressed.
Continuing on schedule may well be right for her — but "we can cover the deficiency" is a reason to keep dosing only if the coverage is as complete as it sounds, and her own infection record over four months says it isn’t.
Given active disease and documented relapse risk, continuing rituximab on schedule with immunoglobulin replacement running alongside it is the right call for her specifically — the infection risk is real but manageable, and stopping a biologic that's actively controlling vasculitis is not a comparable trade.
Immunoglobulin replacement started this visit; rituximab given on the same schedule as planned, with IgG levels now rechecked before every future dose rather than only when an infection prompts it.
Agreed by all three: her case resolved without genuine disagreement once the underlying disease-activity question was answered — the real tension was never Denise's own management, but whether the same logic would hold for a patient whose disease had already resolved.
Arthur L. spent his career as a union electrician and has filled his retirement with restoring a workshop full of donated power tools for a community center, work that requires steadier hands than the fatigue he was feeling two years ago would have allowed. IgG4-related disease, diagnosed after imaging found pancreatic and retroperitoneal involvement, responded well to a rituximab induction course fourteen months ago — his serum IgG4 normalized, his imaging findings resolved, and he has had no clinical or radiographic evidence of active disease on any follow-up visit since. He has no other autoimmune history and, before this diagnosis, had not seen a specialist for anything beyond ordinary primary care in over a decade.
His most recent labs, drawn at a routine follow-up rather than for any new symptom, show a total IgG of 410 mg/dL, and he reports two upper respiratory infections and one case of shingles in the past six months — a change from his infection pattern before treatment, when he says he could not remember his last case of shingles at all. His rheumatologist had scheduled a maintenance rituximab dose for next month, a common practice in IgG4-related disease to reduce relapse risk, but his current disease status shows no activity to actually treat. Makatsori et al., 2014, QJM, found that hypogammaglobulinemia after rituximab can persist for a year or longer in a meaningful subset of patients. What that paper does not address, and what his team has to supply for itself, is the other half of the ledger — whether a maintenance dose is still worth a persistent, documented infection risk when there is no longer any disease activity for it to control. That is the distinction now sitting against the standing maintenance-dosing convention for his diagnosis.
Maintenance rituximab in IgG4-related disease is common practice specifically to reduce relapse risk, and I don't want to abandon that reflexively. But his imaging and IgG4 have been normal at every visit for over a year — there's no active disease finding driving next month's planned dose the way there was for Denise.
That's exactly the distinction that should decide this. Makatsori and colleagues found hypogammaglobulinemia after rituximab can persist over a year in a real subset of patients — that much is measured. The next step is ours, not theirs: with no active disease to control, a maintenance dose buys that persistent risk and nothing against it. I'd hold next month's dose rather than give it on the pre-scheduled maintenance calendar.
Maintenance dosing makes sense as a strategy for preventing relapse in patients still at meaningful risk of it — it stops making sense as a default once there's no disease activity left to actually protect against.
Agreed — hold the maintenance dose, start immunoglobulin replacement given his current IgG and infection pattern, and reassess with repeat imaging and IgG4 levels in three months rather than on the original maintenance calendar. If disease activity genuinely reappears, rituximab is still available; nothing about holding it now forecloses restarting it later if his labs or imaging change.
Immunoglobulin replacement started this visit; the planned maintenance rituximab dose was held, with repeat imaging and IgG4 levels scheduled at three months to determine whether any further biologic dosing is warranted.
Not agreed: whether holding maintenance dosing in confirmed remission should now become a standing practice for other stable IgG4-related disease patients on this team's panel, or whether Arthur's case should be treated as an individual judgment call rather than a new default — left open pending how his three-month follow-up looks.