Nancy M. Vu1, Daniela E. Kirwan2, Jose Lopez3, Robert Gilman4
University of Utah School of Medicine1, Department of Infectious Diseases and Immunity, Imperial College London. UNITED KINGDOM2, Asociacion Benefica PRISMA. CRONICAS - Center of Excellence in Chronic Diseases. Lima3, Johns Hopkins University, Bloomberg School of Public Health. Baltimore, Maryland, USA4
Cachexia is one of the sentinel symptoms of pulmonary tuberculosis (TB). TB causes an inflammatory response that leads to alterations of appetite hormones affecting appetite and satiety. Yet the relationship of TB disease severity and appetite hormone levels has not been well studied, despite its potential utility as an indication of treatment failure.
23 adult patients with sputum positive TB were evaluated on days 0, 14, and 28 days of treatment by Simplified Nutritional Appetite Questionnaire (SNAQ), body mass index (BMI), and appetite and inflammatory markers. Peptide YY, ghrelin, leptin, and IL-10 levels were determined using Luminex and ELISA kits. We also administered a questionnaire to qualitatively determine appetite. Appetite questionnaire results trended towards a gain in appetite with treatment, displaying a significant difference between day 0 vs.14 (ρ=0.004) and day 28 (ρ=0.0095). Peptide YY levels dropped 14.6% by Day 14 of treatment (not significant), while ghrelin levels dropped 54% by Day 14 (ρ<0.05). Leptin levels increased 67.36% by day 28 of treatment (ρ<0.05), and the anti-inflammatory cytokine IL-10 decreased 12.5% by Day 14 (not significant). Subjective appetite improved with treatment as early as day 14, while BMI was slower to respond and still had not increased significantly by day 30. Delayed recovery of weight gain suggests that the increase in leptin is secondary to TB infection. Wasting in TB patients may partly be mediated by upregulation of anorexigenic PYY with resulting appetite suppression. Decrease in IL-10 levels may indicate intact immunity with normal response to treatment. Deviation from improving appetite status, clinical factors and appetite hormone levels may used to detect treatment failure in cases such as multi-drug-resistant TB. While loss of appetite is a well-known symptom of TB, little work has been done in utilizing measurements of appetite in the characterization of the disease, and this work suggests that it may be a useful indicator of treatment success.
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