Factors affecting TST level in patients undergoing dialysis: a multicenter study

Abstract

Introduction: The risk of TB is increased in patients with chronic kidney disease (CKD) when compared with individuals with normal renal function. We aimed to determine tuberculin skin test (TST) response and the factors which might affect the response in patients with CKD undergoing dialysis in this study. Methods: The purified protein derivative solution was administered to the patients and the diameter of induration was measured. Additionally, the age, gender and smoking status of the patients were interrogated. Comorbidities were recorded both by patients' self-reports and data from the hospital files. The number of Bacille Calmette-Guerin (BCG) scars was recorded by checking both shoulders. Findings: The study was conducted with a total of 371 patients (194 men and 177 women). The mean age was 60.09 ± 15.88, TST was 6.99 ± 6.9, duration of dialysis was 4.44 ± 4.5 (3.8–0.1,24). A total of 229 patients have comorbodities (61.7%, the most frequent was hypertension). Logistic regression model was performed. Gender, vitamin D treatment and high parathormone (PTH) levels remained in the final stage of the analysis and vitamin D intake and PTH levels were detected to be statistically significant (P = 0.002, 0.007, respectively). Discussion: This study is the first study which showed a correlation between TST negativity and increased PTH levels and receiving vitamin D treatment. Starting from this point, it was concluded that PTH may suppress the immune system and especially cellular immunity.