TNFSF11 and primary hyperparathyroidism: Individuals with primary hyperparathyroidism have higher levels of RANKL, OPG, and RANKL/OPG ratio than healthy controls (24), and the high levels of RANKL are favorably associated with bone resorption indicators and rates of bone loss at the total femur (25), whereas it has been shown that 1 year after parathyroidectomy (PTX), RANKL/OPG ratio drops (26).