Seasonal variation in serum-25-hydroxyvitamin-D in the elderly in Britain.

In a group of thirty-six non-housebound normal people aged 70 to 88 years living independently in their homes, mean serum-25-hydroxyvitamin-D (+/- 1 S.D.) was 8-62 +/- 3-08 ng/ml in midwinter and had risen to 14-13 +/- 4-90 ng/ml the following September. These values were lower and the seasonal variation was less than previously found in healthy young British adults.