European journal of clinical nutrition
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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. ⋯ 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.