From the history recurrent infections alone do not necessarily mean “low immunity.” Because there has been CNS + pulmonary TB, sepsis, pyelonephritis and frequent respiratory infections, it would be reasonable to investigate both immune deficiency and non-immune causes of recurrent illness.
1. Start with these tests
Test What it looks for
CBC with differential + peripheral smear Neutropenia, lymphopenia, anemia
Absolute lymphocyte count (ALC) Important screening marker for cellular immune deficiency
HIV-1/2 Ag/Ab 4th generation Important acquired immunodeficiency to exclude
Fasting glucose +
HbA1cDiabetes as a cause of recurrent infections
LFT, RFT,
electrolytes,
albumin/total protein Systemic/nutritional causes
Quantitative IgG, IgA, IgM Antibody/humoral immune deficiency
C3, C4 ± CH50 Complement deficiency
Lymphocyte subset analysis: CD3, CD4, CD8, CD19, NK cells T/B/NK-cell abnormalities
2. If the initial tests are abnormal—or infections are unusually severe
An immunologist/physician may add:
* IgG subclasses
* Specific antibody responses/vaccine titres — particularly tetanus and pneumococcal antibodies
* Neutrophil oxidative burst (DHR test) if there is a pattern suggesting phagocyte dysfunction
* Repeat CD4 count, particularly if lymphopenia or HIV-related concern exists
* Serum protein electrophoresis if recurrent infections + low immunoglobulins/protein abnormalities
* Further genetic/primary immunodeficiency testing only if the clinical pattern warrants it.
3. Your history also warrants looking for non-immune causes
The pyelonephritis + bladder/bowel problems particularly deserve a urological evaluation rather than assuming they are due to immunity:
* Urine routine + culture during symptomatic episodes
* Ultrasound KUB
* Post-void residual urine
* Evaluation for urinary obstruction/reflux or bladder dysfunction if recurrent pyelonephritis continues.
For repeated respiratory infections, depending on symptoms:
* Chest X-ray
* HRCT chest if there is persistent/recurrent pneumonia, productive cough, bronchiectasis, etc.
* Pulmonary function testing when appropriate.
One important point about TB
Having pulmonary or CNS TB does not by itself prove that your immune system is weak. TB can occur in otherwise immunocompetent people. However, CNS TB plus recurrent serious infections makes it reasonable to exclude acquired or primary immune problems, particularly HIV, diabetes, lymphopenia and antibody deficiency.
Next Steps
Consult with physician