PTH and Hypocalcemia: A study by Rubin et al. in 2020 on 517 patients with thyroid cancer also showed that the hypocalcemia group had a lower PTH concentration (14.8 ± 15.9 pg/mL) than the group without hypocalcemia (40.2 ± 28.5 pg/mL) with P < 0.01 (21).