PTH and vitamin D deficiency: However, subsequent KDIGO guidelines in 2009 and 2017 did not specify ideal target levels of PTH for patients with CKD stages 3a to 5 who are not undergoing dialysis, but emphasise the significance of addressing modifiable factors in SHPT, such as hyperphosphataemia, hypocalcaemia or vitamin D deficiency, which can contribute to elevated PTH levels.9