Nurse Practitioner Chronicles

Quantitative Immunoglobulins (IgG, IgA, IgM): When to Order, What the Patterns Mean, and the Myeloma Connection Recurrent infections, monoclonal spikes, and the difference between too much of one and not enough of everything else. The Three Immunoglobulins IgG  (700–1600 mg/dL): The workhorse—75% of serum immunoglobulins. Provides long-term immunity after infection or vaccination. Crosses the placenta (maternal IgG protects the newborn). Low IgG = increased risk of bacterial infections. IgA  (70–400 mg/dL): Mucosal immunity—found in saliva, tears, respiratory and GI secretions. Selective IgA deficiency is the most common primary immunodeficiency (1 in 400–800). Connects to our celiac post (IgA deficiency causes false-negative tTG-IgA). IgM  (40–230 mg/dL): The first responder—the initial antibody produced during acute infection. Elevated IgM on infection-specific testing = acute/recent infection. Also the antibody class in Waldenström's macroglobulinemia. When to Order Qu...

  The Celiac Serologic Panel: Getting It Right the First Time Two tests, one massive pitfall, and the number-one mistake that makes the whole workup useless. Celiac disease affects roughly 1 in 100 people, but up to 80% of cases remain undiagnosed. It masquerades as IBS, iron deficiency anemia, unexplained osteoporosis, chronic fatigue, infertility, and even "normal" GI symptoms that patients have lived with for years. The serologic panel is straightforward—but there are pitfalls that will make you miss the diagnosis entirely if you don't know them. Let's get this one right. The Tests: What to Order and Why The First-Line Screen: tTG-IgA + Total IgA That's it. For most patients over age 2, you need exactly  two tests : 1 tTG-IgA (Tissue Transglutaminase IgA Antibody) The preferred screening test per ACG, AGA, and ESPGHAN guidelines. Sensitivity of 93–98%, specificity of 96–98%. This is the workhorse of celiac diagnosis. If it's positive, you're on the righ...