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Vitamin D deficiency in Spain: a population-based cohort study
I González-Molero1, S Morcillo, S Valdés
1Servicio de Endocrinología y Nutrición, Hospital Regional Universitario Carlos Haya, Málaga, Spain. inmagonzalezmolero@hotmail.com
Background:
Vitamin D deficiency is common worldwide. No homogenous reference values have yet been established and no studies of values have been conducted in Spain involving a large number of participants.
Objective:
To study the population concentrations of vitamin D in a representative sample of the Spanish population.
Subjects/Methods:
The study involved two cohorts from Spain, the Asturias study and the Pizarra study, which are two prospective, population-based studies involving 2260 participants. In 1262 subjects (age: 20-83 years) we studied 25-hydroxyvitamin D, intact parathyroid hormone (iPTH), calcium, phosphorus and creatinine.
Results:
The median population values of 25-hydroxyvitamin D and iPTH were 22.46 ng/ml and 42.29 pg/ml, respectively. The values of 25-hydroxyvitamin D were significantly higher in summer and correlated with age (β = -0.05 ± 0.01, P < 0.0001), creatinine (β = 6.42 ± 1.17, P < 0.0001) and iPTH (-0.07 ± 0.01, P < 0.0001), but not with calcium, phosphorus or sex. The increase in iPTH with age was seen whatever the values of 25-hydroxyvitamin D, and was greater in the older persons. The concentration of iPTH rose continuously with effect from 25-hydroxyvitamin D values below ≈30 ng/ml. Values above ≈35 ng/ml were associated with a significantly lower concentration of iPTH.
Conclusions:
One-third (33.9%) of the Spanish population may be at risk for Vitamin D deficiency. The 25-hydroxyvitamin D values above 30 ng/ml can safely discard 'hyper PTH'. The increase in iPTH concentration is greater in older persons for similar values of 25-hydroxyvitamin D.
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