title: Vitamin D status of adults from tropical Australia determined using two different laboratory assays: implications for public health messages.
abstract: We measured serum 25 hydroxyvitamin D [25(OH)D] levels of ambulatory adults in tropical Australia to determine whether it is appropriate to continue promoting sun-safety in this population. In August 2006 (winter), self-administered questionnaires were completed by 145 Meals-on-Wheels volunteers (49.3% male; mean age 57.8 ± 14.7 years; 76.6% response) from Townsville, Queensland (Latitude 19(o) S). Serum 25(OH)D was analyzed using two common assays. Mean levels were 68.3 (SD ± 18.7; range 26-142) by DiaSorin Radioimmunoassay and 83.0 (SD ± 30.8; range 30-184) by DiaSorin Liaison® one. No participants were 25(OH)D deficient (<25 nmol L(-1)). Nine participants (6.2%) had 25(OH)D levels between 25 and 50 nmol L(-1) (insufficient), by both methods (seven with a BMI ≥ 25). Twenty-eight participants (19.3%) had one result in the insufficient range and the other in the adequate range. Thus, almost all of these free-living adults in tropical Australia had adequate vitamin D levels at the end of winter. There was poor agreement between the two 25(OH)D assays. These results suggest it is appropriate to continue promoting sun-safe messages to the ambulatory Caucasian adult population of North Queensland, which has an extremely high incidence of skin cancer. The lack of agreement between the two assays is a concern. Few doctors are aware of this measurement issue.
authors.affiliation: North Queensland Centre for Cancer Research, School of Public Health, Tropical Medicine & Rehabilitation Sciences, James Cook University, Townsville, Queensland, Australia. madeleine.nowak@jcu.edu.au
authors.forename: Madeleine
authors.initials: M
authors.lastname: Nowak
authors.forename: Simone L
authors.initials: SL
authors.lastname: Harrison
authors.forename: Petra G
authors.initials: PG
authors.lastname: Buettner
authors.forename: Michael
authors.initials: M
authors.lastname: Kimlin
authors.forename: David
authors.initials: D
authors.lastname: Porter
authors.forename: Lee
authors.initials: L
authors.lastname: Kennedy
authors.forename: Rick
authors.initials: R
authors.lastname: Speare
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D016273:Occupational Exposure / Q000032:analysis*; D011634:Public Health; D011793:Queensland / Q000453:epidemiology; D011863:Radioimmunoassay / Q000592:standards*; D015203:Reproducibility of Results; D012621:Seasons; D013472:Sunlight / Q000009:adverse effects; D011795:Surveys and Questionnaires; D014329:Tropical Climate; D014466:Ultraviolet Rays / Q000009:adverse effects*; D014807:Vitamin D / Q000097:blood*; D014808:Vitamin D Deficiency / Q000097:blood / Q000453:epidemiology; D044465:White People
chemical_list: D014807:Vitamin D