Fig. (2) Blood parathyroid hormone (PTH) levels in the studied population). a) The graph shows the median value of PTH and bars indicate the 99^th and 1^st percentiles. Dots represent the values of single patients (N.=40). b) In the histogram are reported the median and the respective upper e lower values of PTH of all patients before (baseline), 4 weeks and 12 weeks after the beginning of the therapy and 24 weeks after the end of the anti-viral therapy (follow-up). c) Median with upper and lower values of PTH in patients supplemented (grey bars; N.=27) or not supplemented (white bars; N.=13) with vitamin D before (baseline), 4 weeks and 12 weeks after the beginning of the therapy and 24 weeks after the end of the anti-viral therapy (follow-up).