Standard and advanced immune testing performed at Optimed Immunology, with clinical context for what each test can and cannot tell us.
The immune system is complex, and a single normal lab result rarely rules out an immune problem. Patients are often referred to Optimed after years of standard workups that came back "normal" — not because the workup was wrong, but because the right tests were not ordered, or the results were not interpreted in the full clinical context. The diagnostic approach at Optimed Immunology starts with a thorough history and a focused examination, then uses targeted testing to confirm or rule out specific diagnoses.
Most testing at Optimed Immunology is blood-based, and most can be coordinated through commercial labs (Quest, Labcorp, or your preferred laboratory). Some specialized testing is sent to reference laboratories. The team handles ordering, follow-up, and insurance prior authorization where required.
What it measures: Quantitative immunoglobulins (IgG, IgA, IgM, IgE), IgG subclasses, and lymphocyte subset analysis (CD3, CD4, CD8, CD19, CD16/56).
Used for: Initial screening and ongoing monitoring of suspected primary immunodeficiency, including CVID, IgG subclass deficiency, and lymphocyte abnormalities.
What it cannot tell us: SIP shows the quantity of immune cells and antibodies but not always their function. Normal numbers do not always mean normal function — vaccine response testing or specialized assays may be needed to evaluate function.
Logistics: Standard blood draw at any commercial lab. Most insurance plans cover when ordered for appropriate clinical indication.
What it measures: Specific antibody titers to vaccine antigens (typically pneumococcal serotypes, sometimes tetanus and diphtheria) measured before and after a polysaccharide vaccine (Pneumovax 23). The pattern of response identifies whether the immune system can mount a protective antibody response.
Used for: Diagnosis of Specific Antibody Deficiency — one of the most underdiagnosed causes of recurrent sinopulmonary infection in adults with otherwise normal IgG.
What it cannot tell us: Vaccine response testing assesses one specific aspect of antibody function. It does not evaluate cellular immunity or other arms of the immune system.
Logistics: Performed in stages over 4 to 8 weeks. Baseline labs, vaccination, and post-vaccination labs. The diagnostic process takes time, and results are interpreted in context.
What it measures: The activation of basophils (a type of white blood cell) in response to specific allergens, measured by flow cytometry.
Used for: Adjunctive evaluation in food allergy, drug allergy, and other selected allergic conditions where standard testing is inconclusive.
What it cannot tell us: BAT is one piece of the diagnostic puzzle. Results are interpreted alongside clinical history and standard testing. It does not replace clinical judgment or, where appropriate, supervised oral challenge.
Logistics: Specialized send-out testing. Insurance coverage varies; the team confirms coverage before testing.
What it measures: Detailed flow-cytometric analysis of immune cell populations and function in patients with persistent post-COVID immune symptoms.
Used for: Evaluation of post-COVID immune dysregulation in patients with persistent symptoms despite recovery from acute infection.
What it cannot tell us: Post-acute COVID immunology is an evolving field. Results inform clinical decisions but do not provide a single diagnostic label. Testing is interpreted in the context of symptoms, history, and other findings.
Logistics: Specialized send-out testing.
What it measures: Allergen-specific IgE antibody levels in serum, with or without component-resolved diagnostics that distinguish responses to specific protein components within an allergen.
Used for: Allergy evaluation when blood-based testing is appropriate, including environmental, food, and venom allergens.
What it cannot tell us: A positive specific IgE result indicates sensitization, not necessarily clinical allergy. Many people have positive results to allergens they tolerate without symptoms. Results must be interpreted alongside clinical history. Negative results in the setting of strong clinical history may also warrant additional evaluation, including referral for skin testing or supervised oral challenge.
Logistics: Standard blood draw at any commercial lab. Most insurance plans cover when ordered for appropriate indication.
What it measures: C4 level, C1-inhibitor quantitative level, C1-inhibitor functional assay, and where indicated, genetic testing.
Used for: Diagnosis of hereditary angioedema. Testing pattern confirms HAE type (I or II) or identifies HAE with normal C1-inhibitor.
Logistics: Blood draw at commercial lab; functional assays are send-out.
What it measures: Baseline serum tryptase, with comparison to tryptase measured during a symptomatic episode (drawn within 1 to 4 hours of onset). When indicated, KIT D816V mutation testing and screening for hereditary alpha-tryptasemia.
Used for: Evaluation of mast cell activation syndrome and differential diagnosis from systemic mastocytosis or hereditary alpha-tryptasemia.
Logistics: Baseline tryptase is a standard blood test. Episode tryptase requires patient education on timing. The team coordinates testing logistics.
Optimed Immunology generally orders and interprets testing for established patients. Outside physicians who would like consultation on which tests to order, or who would like Dr. McNeil to interpret results that have already been performed, are welcome to contact the office or send records via fax. See the information for referring physicians for more.
Donald L. McNeil, MD · Board Certified in Allergy & Immunology and Internal Medicine
This page is provided for educational purposes and does not substitute for clinical judgment or direct medical advice. Test interpretation requires the full clinical context and should not be done from lab values alone.