Effect of nutritional status on Tuberculin skin testing

To evaluate Tuberculin skin test (TST) results in a population of immigrants and internationally adopted children from several geographical areas; to analyze whether nutritional status can modify TST results.

This cross-sectional observational study included adopted children and immigrants evaluated in the authors' unit between January 2003 and December 2008. Children diagnosed with tuberculosis, or vaccinated with live attenuated virus 2 mo earlier, HIV-infected, chronically ill or under treatment with immunosuppressive agents were excluded. TST was considered as dependent variable. Independent variables were gender, age, geographical origin, BCG scar, nutritional status, immune status and intestinal parasitism.

One thousand seventy four children were included; 69.6 % were girls. There was a BCG scar in 79 % of children. Mantoux = 0 mm was found in 84.4 %, <10 mm in 4.1 %, and ≥10 mm in 11.4 % of children. Nutrition (McLaren's classification) was normal (≥90 %) in 26.7 % of the subjects, with mild malnutrition (80-89 %) in 36 %, moderate (70-79 %) in 23.2 % and severe (≤69 %) in 14.1 %. There was no difference in TST results among different nutritional status children.

The nutritional status, measured by McLaren's classification, does not changes the results of TST. McLaren's classification only grades protein-caloric malnutrition, so in authors' experience this type of malnutrition does not interfere with TST results. Implementing other nutritional parameters could help to determine whether nutritional status should be taken into account when interpreting TST results.