Baseline Investigations Before Systemic Immunosuppressive Therapy
Before starting systemic immunosuppressive therapy, you must obtain: complete blood count with differential, comprehensive metabolic panel (renal and liver function), fasting glucose/HbA1c, hepatitis B surface antigen (HBsAg) and anti-HBc antibodies, hepatitis C screening, urinalysis, blood pressure, and weight. 1
Essential Laboratory Tests
The core baseline workup includes:
- Complete blood count with differential - Critical for detecting baseline cytopenias before starting myelosuppressive agents
- Renal function (BUN/creatinine) - Necessary as some immunosuppressants require dose adjustment in renal impairment 2
- Liver function tests - Essential since hepatic dysfunction impairs drug metabolism and increases toxicity risk 2
- Fasting glucose and HbA1c - Baseline metabolic assessment before corticosteroid exposure
- Fasting lipids - Pre-treatment cardiovascular risk stratification
- Urinalysis - Screening for occult renal disease
- Blood pressure and weight - Baseline measurements for monitoring steroid effects 1
Mandatory Infectious Disease Screening
You must screen for hepatitis B and C before initiating any immunosuppressive therapy. 2
Hepatitis B Screening (Critical)
- HBsAg (hepatitis B surface antigen)
- Anti-HBc (anti-hepatitis B core antibodies)
This is non-negotiable. Approximately one-third of the world's population has serological evidence of HBV exposure. Patients positive for HBsAg face significant risk of disease flare with immunosuppression, and acute liver failure can occur even in previously asymptomatic carriers when immunosuppression is withdrawn. Transaminases alone are inadequate since they may be normal during the immune-tolerant phase. 2, 3
Hepatitis C Screening
Baseline HCV screening should be performed in all patients to identify those at risk of viral reactivation. 2
HIV Screening
While not universally required, establish baseline HIV status in patients with risk factors. Treated HIV with stable disease on antiretroviral therapy for ≥12 months is not an absolute contraindication, but initiation requires consultation with HIV specialists. 2
Tuberculosis Screening
TB testing is required before initiating biologic therapies, though the evidence provided focuses primarily on anti-TNF agents. 4
Additional Considerations for Specific Agents
If Planning Azathioprine
- TPMT (thiopurine methyltransferase) activity testing - Though practice varies (35-90% of physicians test), this identifies patients at risk for severe myelosuppression 2
If Planning Corticosteroids
- Bone density scan - Should be obtained early in treatment course per osteoporosis prevention guidelines 1
For Female Patients
- Pregnancy test - Required in all women of childbearing potential 1
- Cervical screening status - Ensure compliance with national cervical screening programs; consider gynecology referral if history of CIN, as immunosuppression increases progression risk 2
Additional Baseline Assessments
- Antinuclear antibody (ANA) - Particularly relevant for pemphigus to differentiate pemphigus erythematosus 1
- Height in children - For growth monitoring
- Disease activity measures - Baseline disease severity scores and quality of life assessments for monitoring treatment response 1
Common Pitfalls to Avoid
- Do not rely on transaminases alone for hepatitis screening - they miss patients in immune-tolerant phases
- Do not measure TPMT in patients already on thiopurines - values may be falsely elevated due to enzyme induction 2
- Do not skip hepatitis screening even in low-risk populations - the consequences of reactivation are severe
- Do not forget vaccination counseling - HBV vaccination should be offered to seronegative patients before immunosuppression begins 2