Serum 25-hydroxyvitamin D levels in historical controls and psychiatric inpatients. (A) Normal values for healthy East Anglian adults of mean age 69 years . Circles show means; bars indicate 95% intervals. Solid and dotted horizontal lines indicate suggested thresholds for deficiency and sufficiency, respectively ; toxicity is unlikely with levels below 374 nM [1, 27]. (B, C) Serum 25-hydroxyvitamin D levels of inpatients in the current survey (taken in April–May) shown by age, sex, duration of admission, and supplementation status. Filled symbols show patients on vitamin D supplementation, with label showing supplement amount in international units (IU) per day. Open symbols show those not supplemented. Circles show females; diamonds show males. Solid and dotted lines indicate thresholds for deficiency and sufficiency as before.