Comparison of the prevalence of calcidiol insufficiency in predialysis and osteoporotic populations.

AIM: Calcidiol insufficiency is highly prevalent in chronic kidney disease (CKD) and osteoporotic patients. We assessed and compared calcidiol levels in these two groups from the same geographical area to differentiate environmental factors from characteristics related to CKD.
METHODS: We measured calcidiol levels in 160 predialysis (group 1) and 53 osteoporotic (group 2) patients from a single center. Calcidiol insufficiency was defined as a level between 37.5 and 75 nmol/l and calcidiol deficiency was defined as a level below 37.5 nmol/l.
RESULTS: In group 1, mean glomerular filtration rate (GFR), calcidiol, and parathyroid hormone (PTH) levels were 18.3 +/- 4.7 ml/min, 38.7 +/- 15.1 nmol/l, and 21.9 +/- 19.1 pmol/l. Calcidiol insufficiency and deficiency were present in 98.7% of patients. There was an inverse correlation between calcidiol and PTH levels (r = -0.25; P = 0.001). In group 2, mean GFR, calcidiol levels, and PTH levels were 68.6 +/- 17.6 ml/min, 73.8 +/- 27.1 nmol/l, and 4.23 +/- 1.83 pmol/l, respectively. Calcidiol insufficiency and deficiency were present in 50.9% of patients. There was an inverse correlation between calcidiol and PTH levels (r =-0.44; P = 0.02).
CONCLUSION: In our predialysis population, calcidiol insufficiency and deficiency are present in almost every patient, being more common than previously reported. It is also more frequent than in a similar osteoporotic population, suggesting a cause unrelated to environmental factors. Interestingly, there is a significant inverse correlation between calcidiol and parathyroid levels in both populations. Further studies are needed to enable understanding of the mechanisms underlying calcidiol insufficiency.