PTH and chronic kidney disease: This survey data was comprised of sets A, B and C: trainees who claimed that secondary hyperparathyroidism is a complication of CKD (set A); trainees who screened by stage 3 of CKD (set B); trainees who commenced therapy or referred the patient to a specialist when parathyroid hormone (PTH) reached a level of PTH>70 ng/ml (set C).