PTH and Hypercalcemia: Several such complications induced by excessive vitamin D intake (hypercalcemia, renal insufficiency, hypercalciuria, and undetectable serum PTH) were shown to resolve when serum 25(OH)D3 concentrations dropped below 400 ng/mL in 2 case reports in 2011 after accidental ingestion of massive amounts of vitamin D over a period of 1 to 2 months [60].