Oral doses of vitamin D have been considered as a treatment for psoriasis. This was sparked by experiments with cholecalciferol or 1,25 dihydroxyvitamin D3 (1,25 (OH)2D3), the active form of vitamin D made in the kidney, which showed promise in treating widespread psoriasis. Using a one microgram daily dose of cholecalciferol, Japanese researchers in 1986 managed to treat 13 out of 17 psoriatic patents within three months. But there are risks involved with this therapy. High doses of vitamin D often leads to hypercalcemia (high blood calcium levels) which is characterized by nausea, vomiting, drowsiness, confusion, high blood pressure, kidney failure, and coma. This was observed in the Japanese study and can occur in those taking 1,000 lUs (international units) or more of vitamin D. The topical use of cholecalciferol by the same researchers proved to be more beneficial and less toxic. Sixteen out of 19 patients were treated withi breast enlargement without surgery n three weeks with a dose of 0.5 microgram per gram compared to three months with oral doses. Still, the possibility of hypercalcemia remained since vitamin D is absorbed by the skin. That was until researchers at Leo Pharmaceutical Products in Denmark tried to develop a new form of vitamin D which could clear up psoriatic plaques minus the risks encountered in both oral and topical applications of cholecalciferol. That led to the discovery of calcipotriol. Calcipotriol is a vitamin D3 derivative which is just as effective as cholecalciferol in controlling rapid cell growth in psoriatic skin yet 100 – 200 times less likely to produce hypercalcemia. Unlike other creams and ointments, it is colorless and odorless and generally well-tolerated by patients. This vitamin D3 analogue is recommended for the treatment of plaque-type psoriasis and can be used alone or in combination with UVB radiation (which was tackled earlier in this series).