PTH and vitamin D deficiency: A study conducted in Saudi Arabia observed that PTH was raised in healthy subjects with vitamin D deficiency by 51.8% as assessed by clinical laboratory improvement amendments (CLIA), 66.23% as assessed by radioimmunoassay (RIA), and 100% as assessed by high-performance liquid chromatography (HPLC) or liquid chromatography-mass spectrometry (LC-MS) [22].