What Counts as "Frequent"?
Some infections per year are normal. The following patterns suggest possible immune deficiency and warrant investigation:
- More than 4 ear infections per year (in adults)
- More than 2 serious sinus infections per year
- Two or more pneumonias in one year
- Two or more serious infections (sepsis, meningitis, osteomyelitis) ever
- Infections with unusual organisms (e.g. Pneumocystis, Cryptococcus, atypical mycobacteria)
- Severe or prolonged infections lasting much longer than expected
Causes of Immune Weakness
| Cause | Key Test | Clinical Clues |
|---|---|---|
| Diabetes mellitus | HbA1c, fasting glucose | Recurrent skin, urinary and fungal infections; poor wound healing |
| HIV infection | HIV test (4th generation Ag/Ab combo), CD4 count | Opportunistic infections, weight loss, lymphadenopathy, night sweats |
| Primary immunoglobulin deficiency (CVID, IgA deficiency) | Serum IgG, IgA, IgM levels | Recurrent sinopulmonary infections, bacterial infections |
| Neutropenia | CBC with differential (absolute neutrophil count) | Bacterial and fungal infections; risk if ANC <1.0 x10⁹/L |
| Corticosteroid or immunosuppressant use | Medication review | Steroids, methotrexate, biologics all suppress immunity |
| Malnutrition / Micronutrient deficiency | Albumin, total protein, zinc, Vitamin D | Protein-energy malnutrition, zinc deficiency impair immunity |
Blood Tests for Immune Assessment
| Test | What it Measures | Key Finding |
|---|---|---|
| CBC with differential | WBC types — especially neutrophils and lymphocytes | Low neutrophils (neutropenia) → bacterial risk; low lymphocytes → viral risk, HIV |
| Serum Immunoglobulins (IgG, IgA, IgM) | Antibody levels — the "memory" of immune system | Low IgG especially suggests common variable immunodeficiency (CVID); low IgA is most common primary immunodeficiency |
| HIV test (Ag/Ab) | HIV antigen and antibody | Positive test requires confirmation and CD4 count |
| HbA1c | 3-month average blood sugar | Diabetes is the most common secondary cause of frequent infections |
| Albumin and total protein | Nutritional status and liver function | Low albumin suggests malnutrition, liver disease, or protein-losing enteropathy |
Questions to Ask Your Doctor
- Based on my infection pattern, does this need immune testing?
- Should my immunoglobulin levels be checked?
- Should I have an HIV test?
- Is my diabetes control contributing to my infections?
- Do I need a referral to an immunologist?
Medical Disclaimer: This information is for educational purposes only. Recurrent infections warrant proper medical evaluation to identify any underlying immunodeficiency or systemic condition.