PTH and hypervitaminosis A: Due to the lack of 1,25(OH)2D3-mediated inhibition of RA-induced gene transcription in the T cells of the patient in the present study, it might be suggested that the patient has a functional hypervitaminosis A. Accordingly, despite normal serum levels of calcium, phosphate, alkaline phosphatase and parathyroid hormone, the patient’s main complains were bone pains and hair loss, classical signs of hypervitaminosis A (38, 39).