Role of Anaemia and Magnesium Levels at the Initiation of Tuberculosis Therapy with Sputum Conversion among Pulmonary Tuberculosis Patients.

INTRODUCTION: Both pulmonary Tuberculosis (TB) and anaemia are prevalent in India. Magnesium levels also influence TB. There is limited and inconsistent literature on the association among anaemia, serum magnesium levels and sputum conversion during tuberculosis treatment.

AIM: To study the effect of anaemia and serum magnesium levels on sputum conversion in pulmonary TB patients.

MATERIALS AND METHODS: One hundred each of newly diagnosed sputum smear positive Pulmonary Tuberculosis (PTB), sputum smear negative PTB patients initiated on Directly Observed Treatment Short Course chemotherapy (DOTS) and healthy age and sex matched controls were recruited in the study. Patients were followed up prospectively until completion of first two months of intensive phase. Patients were evaluated before initiation of TB treatment by performing the complete blood counts with peripheral blood smear, serum biochemistry, serum iron, serum magnesium, serum ferritin and microscopic examination of sputum. After giving two months of Antitubercular Therapy (ATT), sputum smears were re-examined for presence of acid fast bacilli. Haemoglobin values less than 13 g/dl in males or 12 g/dl in females was defined as anaemia. Mean and Standard deviations were calculated. Independent t-test was used to compare between the groups.

RESULTS: Serum iron and serum ferritin was significantly lower in sputum positive PTB as compared to sputum negative PTB and controls. Anaemia was present in 162 (81%) patients of the study PTB cases. About 60% of anaemia in sputum positive cases was iron deficiency anaemia. Serum magnesium level was significantly lower in sputum positive PTB as compared to sputum negative PTB and controls though not in hypomagnesemic range. Delayed sputum smear conversion occurred in 12 (12%) sputum positive PTB patients. Of these, eight had severe iron deficiency anaemia, four with moderate anaemia. All 12 delayed sputum smear conversion had serum magnesium levels < 1.7 mg/dl (below normal reference range) (mean 1.42 ±0.22 mg/dl).

CONCLUSION: Sputum was found to be positive even after two months of ATT course because of baseline anaemia and lower levels of serum magnesium. Further multicentric studies are warranted to study mechanisms for TB associated anaemia and possible role of intervention for anaemia in TB patients. One needs to find out the mechanisms behind the role of anaemia and lower magnesium levels in delaying the sputum smear conversion in order to lay the foundation of effective interventions. Randomized controlled trials are warranted to generate higher levels of evidences to support our findings.