| Overdose can lead to hypervitaminosis D and hypercalcaemia. Symptoms of hypercalcaemia may include anorexia, thirst, nausea, vomiting, constipation, abdominal pain, muscle weakness, fatigue, mental disturbances, polidipsia, polyuria, bone pain, nephrocalcinosis, renal calculi and in severe cases, cardiac arrhythmias. Extreme hypercalcaemia may result in coma and death. Persistently high calcium levels may lead to irreversible renal damage and soft tissue calcification.Treatment of hypercalcaemia: the treatment with calcium and vitamin D must be discontinued. Treatment with thiazide diuretics, lithium, vitamin A and cardiac glycosides must be also discontinued. Fluid deficiency should be balanced and individual rescue measures should be decided by the doctor. Rehydration, and, according to the severity, isolated or combined treatment with loop diuretics, bisphosphonates, calcitonin and corticosteroids. Serum electrolytes, renal function and diuresis must be monitored. In severe cases, ECG (electrocardiogram) and CVP (central venous pressure) should be followed.The threshold for vitamin D intoxication is between 40,000 and 100,000 IU/day for 1-2 months in persons with normal parathyroid function, for calcium in excess of 2,000 mg per day. Symptoms of vitamin D intoxication are due to hypercalcaemia and should be treated as indicated above.
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