Unfortunately, there is no information on herbs effects on the Parathyroid glands, there is no research and traditionally people had no idea these glands existed. Osteoherb along with Calcium, Vitamin D, Boron, Magnesium, Potassium. K2, etc may slow the leaching of calcium from the bones, but again there is little data and they will not alter the increased levels of PTH.. In an animal study (rats) a TCM formula Liu Wei Zhuanggu did reduce PTH levels. There is not data as to if it works in humans. BTW Rocaltriol is synthetic D3.