The booster phenomenon of tuberculin skin testing in patients receiving hemodialysis.

BACKGROUND The risk of developing tuberculosis is high among chronic hemodialysis patients. The tuberculin skin test (TST) has been in use for diagnosing latent TB, but few data are available on TST in hemodialysis patients. OBJECTIVE This study was done to identify the TST reactivity and frequency of booster effect in serial TST among hemodialysis patients. METHODS A total of 100 patients in three hemodialysis centers were prospectively tested. Patients with less than 10mm indurations were given additional TST one and four weeks later to determine the frequency of booster effect. RESULTS The cumulative prevalence of a positive TST was 7 % for the first test and 16 % for the third test. There was a weak, but significant correlation between TST positivity, serum albumin level, urea reduction ratio and KT/V (p<0.05). There was no influence of age, gender, hemodialysis duration and primary renal disease. CONCLUSION This study showed that the TST reactivity and booster effect among our hemodialysis patients in Iran are lower than in other societies. Inadequate hemodialysis and poor nutrition may contribute to the lower tuberculin skin test reactivity in our hemodialysis patients.