PTH and hypercalcemia disease: However, excessive intake can be harmful, as Chatterjee et al. reported a case of reversible parkinsonism induced by VitD toxicity, where a patient developed tremors, rigidity, and cognitive impairment after prolonged high-dose supplementation (60,000 IU/week for four years), resulting in hypercalcemia and suppressed parathyroid hormone levels [210].