PFI and WI before and after loading with vitamin D in vitamin D deficient patients

Antonis Polymeris; Stavroula Psachna; Dimitrios Ioannidis; Dimitrios Lilis; Maria Drakou; Peter Papapetrou

doi:10.1530/endoabs.90.EP165

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Endocrine Abstracts (2023) 90 EP165 | DOI: 10.1530/endoabs.90.EP165

ECE2023 Eposter Presentations Calcium and Bone (99 abstracts)

PFI and WI before and after loading with vitamin D in vitamin D deficient patients

Antonis Polymeris ¹ , Stavroula Psachna ¹ , Dimitrios Ioannidis ¹ , Dimitrios Lilis ¹ , Maria Drakou ¹ & Peter Papapetrou ¹

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¹Sismanogleio-Amalia Fleming Hospital, Department of Endocrinology, Metabolism and Diabetes Mellitus, Athens, Greece

Aim: To evaluate the change in PFI (Parathyroid Function Index) and WI (Wisconsin Index) after loading with vitamin D in patients with vitamin D deficiency.

Patients and Methods: In 41 vitamin D deficient patients (25(OH)₂D<17.16±6.07 ng/ml, mean±SD) the PFI (PTHxCa devided by P) and the WI (PTHxCa) were evaluated before and after 3 month loading with Vitamin D 50.000 IU per week for the first 6 weeks and 25.000 IU per week for the next 6 weeks.

Results: 25(OH)₂D increased significantly (P<0.0001) and PTH decreased significantly (P=0.001) after 3 month loading with vitamin D while serum calcium and phosphorus showed no change (P=0.16 and P=0.19 respectively). PFI and WI decreased significantly after loading from 17.9±8.2 (mean±SEM) to 13.3±7.4 and from 20.4±8.3 to 14.5±6.9, P=0.001 and P=0.0008 respectively. Considering a 25(OH)₂D level as the best between 20-50 ng/ml and taking as cut-off value of 25(OH)₂D 20.2 ng/ml, the analysis showed for the PIF sensitivity 68.3% and specificity 36.6%, and for the WI sensitivity 68.3% and specificity 53.7%.

Conclusion: PFI and especially WI can potentially be used as indicators of adequate vitamin D loading along with a remeasurement of vitamin D considering that most of the commercial Vitamin D assays overestimate its serum levels.