To the Editor.
—The study by Dr Gloth and colleagues1 may be incorrectly interpreted as implying that because of outdoor exposure, nonhomebound elderly persons are not at risk for vitamin D deficiency. Reduced serum 1,25-dihydroxyvitamin D3 and increased parathyroid hormone (PTH) levels were detected in the homebound ill relative to the non-homebound healthy elderly individuals. It was concluded that "homebound elderly persons are likely to suffer from vitamin D deficiency," imparting the impression that nonhomebound elderly individuals are not at risk because of outdoor exposure. Instead, this lack of deficiency may have been dependent on adequate vitamin D ingestion or serum sampling favoring seasons when routine outdoor exposure (ultraviolet B radiation) in Baltimore, Md, yields sufficient cutaneous vitamin D synthesis.Although vitamin D ingestion was quantified and the above serum levels studied were not significantly different by season for the homebound elderly, this information regarding the nonhomebound controls