Explain the Toxicity of Vitamin D?

The adverse effects of high vitamin D intakes include hypercalciuria (excessive urinary calcium excretion) and hypercalcaemia (high concentration of calcium in blood). Excessive amounts of vitamin D are not normally available from dietary sources, and hence cases of vitamin D intoxication are rare. Nevertheless, toxicity may occur in individuals on excessive amounts of supplemented vitamins, for example, drinking milk fortified with inappropriately high levels of vitamin D₃. The signs and symptoms associated with it are anorexia, nausea and vomiting, followed by polyuria, polydipsia, weakness, nervousness and pruritis (itchiness). Renal function is impaired and metastatic calcifications may occur, particularly in the kidneys.