Malnutrition in tuberculosis: value of fat-free mass and creatinine-height index

Abstract

Background

The association between tuberculosis (TB) and undernutrition has long been known. TB worsens undernutrition and undernutrition weakens immunity, thereby increasing the likelihood that latent TB will develop into active disease.

Objective

The aim of the study was to measure the fat-free mass, creatinine-height index (CHI) and other anthropometric measures, and serum albumin to assess the nutritional status of TB patients and to estimate the value of these indexes as prognostic factors of the disease.

Patients and methods

The present prospective analytic case–control study was conducted in the Chest Department, Assiut University Hospital. The nutritional status of 61 TB patients and 68 controls was assessed. Anthropometric measures such as ideal body weight (IBW), BMI, triceps skin-fold thickness, arm muscle area (AMA), fat mass index, and fat-free mass index (FFMI) were recorded, as well as laboratory assessment of CHI and serum albumin.

Results

There is significant decrease in BMI and IBW% (P < 0.01) in TB patients. The lean body mass using AMA and FFMI is significantly lower in TB patients than in controls (54.2 ± 6.9 vs. 61.9 ± 4.7 cm and 34.3 ± 5.0 vs. 35.8 ± 3.4 cm, respectively; P < 0.01). Loss of fat in TB patients is indicated by significant reduction in mid-arm circumference, skin-fold thickness, and fat mass index (P < 0.01 each). TB patients have significantly lower CHI and serum albumin compared with controls (76.5 ± 28.1 vs. 91.7 ± 24.2 and 37.4 ± 7.8 vs. 41.6 ± 4.2; P < 0.01). Using multiple regression, the significant determinants of malnutrition in TB patients are IBW, AMA, CHI, and serum albumin.

Conclusion

Tuberculous patients have significantly decreased body weight with loss of both lean body mass and fat mass. The loss of CHI is a more significant marker than FFMI in this group of patients. These indexes as well as serum albumin may play an important role as prognostic markers in TB.