Serum vitamin D metabolites in normal subjects after phototherapy

The serum concentrations of the major vitamin D metabolites (25-hydroxyvitamin D(2 + 3) (25-OH-D), 1,25-dihydroxyvitamin D(2 + 3) (1,25-(OH)2-D), and 24,25-dihydroxyvitamin D(2 + 3) (24,25-(OH)2-D) were studied in 22 healthy male volunteers before and after one or two treatments with whole body UVB or PUVA in conventional doses. The effect of UVB was investigated in the autumn and early spring, whereas the effect of PUVA was investigated only in the autumn. The pre-treatment values of two metabolites were significantly reduced in the spring compared to the autumn level (25-OH-D: 14.0 ng/ml versus 22.0 ng/ml, P less than 0.02; and 24,25-(OH)2-D: 1.23 ng/ml versus 2.74 ng/ml, P less than 0.01), whereas the serum concentration of 1,25-(OH)2-D was not significantly reduced in the spring. After UVB, a small, but not significant, rise in all metabolites was observed in the spring, whereas virtually no changes were measured after UVB or PUVA in the autumn. We conclude that UVB and PUVA do not lead to harmful concentrations of vitamin D metabolites in the blood of healthy subjects.