Is it okay to administer a Tuberculin Skin Test (TST) and a steroid injection at the same time?

Administering a Tuberculin Skin Test (TST) and Steroid Injection Simultaneously

It is acceptable to administer a Tuberculin Skin Test (TST) and a steroid injection at the same time, but the steroid injection may suppress the TST response and lead to false-negative results. 1

Effect of Steroids on TB Testing

Impact on Test Accuracy

• Steroids, particularly oral prednisolone, can significantly suppress both TST and IGRA (Interferon-Gamma Release Assay) responses 2
• Oral prednisolone has been shown to severely impair interferon-gamma response to mitogen stimulation, increasing the risk of:
  • False-negative TST results (adjusted odds ratio 0.22) 2
  • Indeterminate IGRA results (adjusted odds ratio 16.1) 2
• Even short courses of high-dose steroids can potentially reactivate latent TB infection 3

Timing Considerations

• If the steroid injection has already been given, the TST should be delayed for at least 4 weeks after steroid administration to avoid potential suppression of TST reactivity 1
• If the TST must be performed and cannot be delayed, consider the following options:

Recommended Approach

Option 1: Perform TST First (Preferred)

• Administer and read the TST before giving the steroid injection 1
• This approach ensures the TST result is not affected by the immunosuppressive effects of steroids

Option 2: Simultaneous Administration

• If simultaneous administration is necessary due to logistical reasons:
  • Be aware that the steroid may potentially suppress the TST response 1, 4
  • Consider using an IGRA test (QuantiFERON-TB Gold or T-SPOT.TB) in addition to TST for higher sensitivity 1
  • Document that the patient received a steroid injection at the time of TST placement

Option 3: Alternative Testing

• Consider using an IGRA test instead of TST if the patient needs immediate steroid therapy 1
• IGRAs may be less affected by some forms of immunosuppression, though prednisolone can still impact their results 2

Special Considerations

For High-Risk Patients

• For patients with increased risk of TB infection or progression:
  • Consider dual testing with both TST and IGRA for increased sensitivity 1, 5
  • This is particularly important for immunosuppressed patients or those with risk factors for TB 1

Risk Factors to Consider

• History of TB exposure
• Origin from or travel to TB-endemic areas
• Planned immunosuppressive therapy (especially anti-TNF agents) 1
• Presence of other immunocompromising conditions

Practical Recommendations

1. Document baseline TB status before initiating any immunosuppressive therapy when possible
2. If steroid injection is urgent and cannot be delayed, proceed with both but document the potential for false-negative TST results
3. Consider follow-up testing if there is high clinical suspicion for TB despite negative initial testing
4. For patients planning to start anti-TNF therapy, complete proper TB screening before initiating steroids if possible 1

Remember that the accuracy of TB testing is critical for patients who may need immunosuppressive therapies in the future, as undiagnosed latent TB can reactivate during treatment with biologics or other immunosuppressants.