Do you recommend stopping Vitamin D supplementation in a patient with hypercalcemia and a low 25(OH)D level?

Even though nutritional vitamin D does not normally cause hypercalcemia except in very high doses, I'm not so confident that it is not a contributing factor to the problem in dialysis patients. The reason is mainly a lack of data in this population which has some unique issues related to PTH levels, bone disease, calcium intake, and excretion, etc. I would still tend toward replacement in patients with clear deficiency (less than 20 ng/dl) but even here one should be aware that granulomatous disease can activate 25 OH D so rapidly that 1,25 D can reach toxic levels even with "deficient" levels of 25 OH D. A reasonable course of action would be to act based on an assessment of whether stopping vitamin D has any benefit being aware of the very long half-life of cholecalciferol and the slightly lower half-life of ergocalciferol (ie wait 2 or 3 months).