Urine calcium excretion during treatment of psoriasis with topical calcipotriol

Urine calcium excretion is a very sensitive method of detecting vitamin D intoxication, and may rise in the absence of any apparent change in the serum level. Little attention has been paid to urine calcium levels during the large trials performed to assess the efficacy and safety of calcipotrioi in psoriasis vulgaris. There are some urine calcium data from short-term studies of average dose rates of calcipotriol. However, there are no published data on long-term usage, nor on the use of dose rates at the upper end of the licensed range (100 g/week). In a group of 20 patients, who were using typical quantities of calcipotriol ointment (50 μg/g) to treat psoriasis vulgaris, urine calcium excretion was measured prior to treatment, and then monthly for 1 2 months. There was no significant change in urine calcium over the year. In a separate group of 10 patients, who were using calcipotriol in the same concentration, at the maximum recommended rate of 100 g/week, urine calcium was measured at baseline, and after 2 and 4 weeks. There was a statistically significant rise in calcium excretion. This is the first trial to demonstrate that topical calcipotriol affects calcium homeostasis when used within the recommended dose range. Further studies are necessary to determine more precisely the magnitude and variability of this effect in a large group of individuals. For the present, caution is required when prescribing calcipotriol for any patient with known hypercalciuria or a history of renal stone formation. Consideration should be given to monitoring urine calcium excretion during prolonged use at dose rates approaching the recommended maximum.