Vitamin D and PTH: optimal values and prevalence of disorders

Vitamin D deficiency is very common, its prevalence has reached pandemic levels worldwide. The definition of vitamin D insufficiency is not yet consensual, in the absence of Algerian data, this work was designed with the objective of determining the prevalence of vitamin D insufficiency, to identify its predictive factors and to establish optimal values, both for vitamin D and for PTH. In the first part, the particularly frequent character of vitamin D insufficiency was confirmed, it concerns 94.6%, 85.5% and 52.1% of the population, respectively at the threshold of 30ng/ml, 20ng/ml and 10ng/ml. Using the decision tree algorithm approach, the most determining factors were identified, in ascending order of: duration of daily exposure to the sun, weekly frequency of consumption of oily fish, age group of the subject, season of sampling, phototype and sex. In the second part, we used the nonlinear inverse relationship between 25(OH) D and PTH to determine the optimal vitamin D value.