In Recurrent URIs, Don't Order That Immune Test Just Yet

Recurrent URIs: Where to Start?

Allergist-immunologists are frequently asked to evaluate patients with recurrent upper respiratory infections (URIs) for immune deficiency. It is very easy to order immune globulin studies but it's often not necessary, and a detailed history can better select for the appropriate patient for that workup. After two decades of practice studying the allergic, immunologic, and endoscopic features of patients with recurrent sinus infections, I have come to understand that there are many mundane explanations beyond antibody deficiency and that a detailed history (as always in medicine) is the best place to start. The most basic thing to consider is whether the "sinus infections," for example, were really bacterial in the first place. Sometimes patients with frequent sinus infections simply have sinus pressure with allergy or colds. You must ask the patient what they mean when they say "sinus infections," how long they wait before seeing a doctor for antibiotics, and what happens if they do not take antibiotics.

Even if the history does indeed suggest recurrent bacterial infections, it's important to remember that the vast majority of these patients do not have immune deficiency, but instead probably have much more mundane explanations. Here is my suggested checklist of the most common triggers of URIs:

Allergy: It is obvious but needs to be stated that patients with frequent sinusitis corresponding to allergen exposure have a ready explanation for sinus infection. Even if the history strongly suggests bacterial sinusitis, the evaluation should include nasal endoscopy in addition to allergy testing to identify other factors.
Anatomy: Nasal endoscopy is a critical part of the workup of the patient with recurrent sinusitis to identify septal deviations, nasal polyps, and chronic sinusitis. A CT scan is complementary but not preferable to this.
Frequent respiratory pathogen exposure: Pediatricians typically get sick a lot during their training, as do preschool teachers and parents of young children who are in daycare. The typical scenario is one of back-to-back URIs that may mimic sinusitis or culminate in bacterial sinusitis. This can sometimes evolve into chronic sinusitis.
Air travel: Many people have sinus and ear symptoms with airplane flights. A recent study identified an association between air travel and sinus disease.^[1] The causes for this may include airborne respiratory irritants, shifts in barometric pressure, nasal dryness, and exposure to sick passengers in closed quarters. During descent, the air pressure on the ostia may increase from the nasal to the sinus side, while during ascent, the sinus cavity may expand against the ostia. In addition, frequent air travelers also suffer from another contributing factor—sleep deprivation.
Sleep deprivation: Studies in both humans and animals have demonstrated deleterious effects on cytokine and immune cell functions as a result of sleep deprivation.^[2] Clinically, it has been shown that sleep-deprived persons do not respond as well to influenza A vaccination^[3] and are more likely to contract the common cold.^[4]
Cigarette smoke exposure: This seems to be more of an issue with chronic rhinosinusitis for daily smokers. I wonder, however, whether more intermittent smoking (social smoking, hookahs, and legalized marijuana) might lead to recurrent acute sinusitis.

When It's Time to Consider Immune Deficiency

When, therefore, should antibody immunodeficiency rise to the top of your differential diagnosis list? I think of it sooner if patients have any of the other conditions associated with immunoglobulin (Ig)A or common variable immunodeficiency. This includes a history of recurrent acute otitis and sinusitis (not chronic sinusitis), especially dating back to childhood, and autoimmune disease, inflammatory bowel disease, and history of pneumonia.

Remember also that the Ig level alone is seldom enough to diagnose humoral immunodeficiency. Many patients with modestly reduced IgA, IgM, IgG, and IgG subclasses are immunocompetent, as evidenced by specific antibody responses. Even if the diagnosis of humoral antibody deficiency seems correct, do not forget the other common causes of respiratory infections.

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