Yes, C-reactive protein (CRP) is typically elevated in active tuberculosis (TB).
Understanding CRP and its Role in TB
CRP is a non-specific marker of inflammation in the body. This means that elevated CRP levels can indicate various conditions, not just TB. However, studies show a strong correlation between elevated CRP levels and active TB. Several research papers indicate high sensitivity in detecting pulmonary tuberculosis. One meta-analysis found a pooled sensitivity of 93% (95% CI 85–97) in detecting pulmonary TB. [^1, ^2, ^3]
- Elevated CRP in Active TB: Studies consistently demonstrate that CRP levels are significantly higher in individuals with active TB compared to healthy individuals. One study reported a mean CRP concentration of 114.7 mg/L (95% CI: [83.8–145.6]) at diagnosis in TB patients. [^4]
- CRP and TB Treatment: Importantly, CRP levels tend to decrease with successful TB treatment, further supporting its association with active disease. [^5]
- CRP as a Diagnostic Tool: While CRP is not a specific diagnostic test for TB (it's elevated in many other infections as well), its elevated levels can be a useful indicator, particularly when combined with other diagnostic tests and clinical assessments. The sensitivity of CRP as a screening test is quite high, exceeding 90% in some cases, especially when employing diagnostic methods like the Xpert Gene test. [^6, ^7]
- CRP and Mortality Risk: High CRP levels (≥10 mg/L) in HIV-infected individuals have been associated with increased mortality risk, both disease-specific and all-cause mortality. [^5]
It is crucial to remember that CRP is a nonspecific marker; therefore, high CRP levels alone cannot definitively diagnose TB. Further investigations, including chest X-rays, microbiological tests (e.g., sputum culture), and other diagnostic tools are necessary for a confirmed diagnosis.
[^1]: A 2017 meta-analysis on diagnostic accuracy of C-reactive protein found a high pooled sensitivity (93%, 95% CI 85–97) to detect pulmonary tuberculosis, with no publication bias.
[^2]: CRP sensitivity reached higher values than 90% in cases of TB diagnosed through Xpert Gene test; therefore, CRP usage could provide cost-effective and rapid screening.
[^3]: It is known to be elevated in active TB, bacterial and fungal infections and to fall with treatment of TB and other infections.
[^4]: The mean concentration of CRP in TB patients was 114.7 mg/L (95 % CI: [83.8–145.6]) at diagnosis.
[^5]: It is known to be elevated in active TB, bacterial and fungal infections and to fall with treatment of TB and other infections; elevated CRP (10 mg/L) predicts disease-specific and all-cause mortality risk among HIV-infected persons.
[^6]: CRP sensitivity reached higher values than 90% in cases of TB diagnosed through Xpert Gene test; therefore, CRP usage could provide cost-effective and rapid screening.
[^7]: Among those who were M. tuberculosis culture positive, 36 had CRP levels of ≥10 mg/liter, providing a sensitivity.
