Alkaline Phosphatase Levels in Tuberculous Cervical Lymphadenitis - Could it be a Predictor for Diagnosis and Monitoring Response to Anti-tuberculous Treatment.

ABSTRACT

Introduction: Scrofula also known as tuberculous cervical lymphadenitis is one of the most common manifestations of tuberculosis (TB). India is a country that still remains plagued by this dreaded disease. The disease poses both diagnostic and therapeutic challenges because it mimics other pathologic processes and does not have consistent physical and laboratory findings. The monitoring of treatment in cases of cervical TB lymphadenitis is more complex due to the peculiar behavior of TB lymph nodes. Materials and Methods: The serum alkaline phosphatase (ALP) of all patients presenting with cervical TB lymphadenitis in the Revised National TB Control Programme (RNTCP) outpatient department (OPD) of MS Ramaiah Medical College was collected. An ALP level at the time of diagnosis was noted. Subsequently, serum ALP levels were measured when the patients come for Directly Observed Treatment Short to RNTCP OPD on 15th, 30th, and 60th day of starting anti-TB treatment (ATT). Results: It has been observed in the study that 72.2% of the patients with cervical tuberculous lymphadenitis had significantly elevated levels of serum ALP (>135 IU/L) at the time of presentation. Only 5.3% among the controls had high ALP, and the difference was statistically significant with a P < 0.001. With sensitivity = 72.2% and specificity of 94.5%, and assuming that the prevalence of TB is 3.2% the estimated positive predictive value is 30.3% and negative predictive value is 99.0%. Based on simple linear regression with ALP as dependent variable and time as independent variable, it is found that among the patients there is a decline in ALP values at an average of 33.4 in every 15 days. Conclusion: This study shows the significance of measurement of serum ALP as a supplementary tool in the diagnosis of cervical TB lymphadenitis. Serial monitoring of serum ALP can be used to monitor the response of ATT.