PTH and secondary hyperparathyroidism: Additionally, secondary hyperparathyroidism (SHPT), a major component of chronic kidney disease–mineral and bone disorder (CKD–MBD), is known to result in resistance to erythropoietin; shortened survival of RBC via the accumulation of high levels of parathyroid hormone (PTH), a uremic substance; and decreased hematopoiesis due to myelofibrosis, which partially explains the pathways linking CKD and anemia[5,6].