the effect of ramadan fasting on tuberculin skin test and leukocyte count

background & objectives: annually, many muslims fast during the month of ramadan worldwide. this practice has different favorable medical and physiological effects, such as improved serum lipid profile and blood glucose level due to changes in diet and sleep patterns. it has also been hypothesized that ramadan fasting may affect the immune system. as reported, ramadan fasting can influence the immunoglobulin and cytokine levels. accordingly, tuberculin skin test or purified protein derivative (ppd) test, which is a delayed-type hypersensitivity of cellular immune response, may also be affected by ramadan fasting. regarding this, the present study aimed to investigate the alteration of ppd test during and after ramadan. materials & methods: a total of 42 males (seminary students) who fasted during ramadan in 2006 were included in the study; however, only 28 cases completed the study. for data collection, the participants underwent blood and tuberculin tests at the fourth week of ramadan and three months after this month. the white blood cell (wbc) count and the tuberculin induration were recorded and compared between the two intervals to evaluate the changes. results: according to the results of the study, the mean age of the participants was 19.21±3.83 years. furthermore, the mean tuberculin induration was 9.3±5.4 mm (size range: 2-22 mm) on the fourth week of ramadan, which increased to 9.79±6.8 mm (size range: 3-35 mm) three months after this month (p=0.501). the mean count of wbc decreased insignificantly from 5907±1879 mcl to 5601±1362 mcl after ramadan (p=0.334). additionally, the mean lymphocytes count decreased significantly from 2292±520/mcl to 2023±486/mcl after this month (p=0.003). likewise, the lymphocyte (p=0.014) and mean neutrophil percentage also reduced significantly (p<0.001). however, there was no association between ppd test and wbc, lymphocyte, or neutrophil count (p>0.05). conclusion: as the findings of the present study indicated, ramadan fasting induce some changes in the immune status, including lymphocyte and neutrophil percentage and count; however, it does not affect the ppd results.