Observational study data suggest that it may be possible to prevent development of secondary hyperparathyroidism by increasing vitamin D levels to 40 ng/mL or higher, investigators reported in the American Journal of Kidney Diseases.
Rita L. McGill, MD, MS, of the University of Chicago I Illinois, and colleagues examined parathyroid hormone (PTH), vitamin D, and calcium values in 153,611 patients with stage 1-5 CKD not on dialysis (56.6% female; mean age 65.9 years). PTH levels generally increased with CKD stage. However, at each CKD stage and serum calcium concentration (from 8.5 to 10.2 mg/dL), median PTH levels were 20% to 40% lower when 25(OH)D levels were 40 ng/mL or higher compared with less than 20 ng/mL or deficient, the investigators reported. Patients with low 25(OH)D levels of 20 to less than 40 ng/mL had intermediate PTH levels. Estimated glomerular filtration rate remained the strongest determinant of PTH.
“These observational data generate a hypothesis that repleting 25(OH)D levels to ≥40 ng/mL could be a possible intervention to prevent the development of secondary hyperparathyroidism during CKD stages 3-5, despite lack of evidence for vitamin D to reverse established hyperparathyroidism,” Dr McGill’s team wrote.
The 2017 KDIGO guideline for chronic kidney disease-mineral bone disorder (CKD-MBD) recommends that vitamin D deficiency in nondialysis CKD be treated similarly as in the general population. Dr McGill and colleagues contend that correcting 25(OH)D deficiency in the CKD population according to general guidelines may be too conservative.
A study of patients with stage 3 to 4 chronic kidney disease (CKD) found that PTH suppression did not occur until 25(OH)D levels reached 50.8 ng/mL.
Additional studies on therapies to increase 25(OH)D levels in CKD stages 3-5 are warranted.
Dhillon-Jhattu S, McGill RL, Ennis JL, Worcester EM, Zisman AL, Coe FL. Vitamin D and parathyroid hormone levels in CKD. Am J Kidney Dis. Published online August 2, 2022. doi:10.1053/j.ajkd.2022.06.006