PTH and Huntington disease: In the COSMOS study of 4500 European HD patients evaluated at 6-month intervals, Fernandez-Martin et al. reported that a serum PTH decrease was not associated with an increased rate of mortality when baseline PTH levels were within the KDIGO range of normal (168 – 674 pg/mL), with the risk of mortality significantly increasing among patient with a baseline PTH level <168 pg/mL [15].