Conclusions This systematic review demonstrates that body weight is an important predictor of variation in circulating 25OHD in cohorts on vitamin D supplements .
Our model provides an estimate of the daily vitamin D dose that is necessary for achieving adequate circulating 25OHD levels in vitamin D-insufficient or vitamin D-deficient individuals/cohorts with different body weights and ages
Purpose There is considerable variation in incremental circulating 25-hydroxyvitamin D ( 25OHD ) levels on vitamin D supplements , even when similar age groups and identical vitamin D doses are compared .
We therefore aim ed to investigate the importance of body weight for the dose – response relation in circulating 25OHD .
1,25-Dihydroxyvitamin D fluctuations in cardiac surgery are related to age and clinical outcome*
Objective : To investigate the interrelationship between cardiac surgery , age , circulating concentrations of the vitamin D hormone 1,25-dihydroxyvitamin D , and clinical outcome . Design : Prospect i ve , monocentric , two-arm parallel study . Setting : Tertiary Heart and Diabetes Center in the Federal State of North Rhine-Westphalia , Germany . Patients : Twenty-nine cardiac surgical patients aged ⩽65 yrs and 30 patients ≥75 yrs . Measurements : We assessed  1,25-dihydroxyvitamin D and other biochemical parameters of mineral metabolism ( calcium , phosphate , 25-hydroxyvitamin D , and parathyroid hormone ) , various inflammatory markers ( C-reactive protein , interleukin-6 and 8) , and different immunological parameters ( CD4 and CD8 cells , monocyte HLA-DR expression ) . We collected blood sample s preoperatively , immediately after surgery , and on postoperative days 1 , 5 , and 30 . In addition , we assessed adverse outcome until discharge as a composite of myocardial infa rct ion , low cardiac output syndrome , infection , stroke , or in-hospital death . Results : There were significant transient cardiac surgery-related fluctuations in 1,25-dihydroxyvitamin D and the aforementioned parameters of mineral metabolism , inflammation , and immune status . Compared to younger patients , older patients had consistently lower 1,25-dihydroxyvitamin D and phosphate levels ( p = .013 and p = .036 , respectively ) and significantly higher interleukin 6 and 8 levels ( p = .008 and p < .001 , respectively ) . Circulating 1,25-dihydroxyvitamin D was directly related to glomerular filtration rate ( R2 = .227 ; p < .001 ) and inversely related to interleukin 6 ( R2 = .105 ; p = .012 ) . The rate of adverse outcome tended to be higher in older than in younger patients ( 20.0 % vs. 3.5 % ; p = .081 ) . In risk score-adjusted logistic regression analysis , adverse outcome risk decreased by 7.7 % ( SE : 3.7 % ) for each pmol/L increment in 1,25-dihydroxyvitamin D ( p = .037 ) . Conclusions : Circulating 1,25-dihydroxyvitamin D levels fluctuate in relation to cardiac surgery . Low 1,25-dihydroxyvitamin D levels are associated with inflammatory processes and age-related differences in clinical outcome . Future studies should determine whether therapies aim ed at treating low 1,25-dihydroxyvitamin D levels can improve the outcome in older cardiac surgery patients
Conclusions This systematic review demonstrates that body weight is an important predictor of variation in circulating 25OHD in cohorts on vitamin D supplements .
Our model provides an estimate of the daily vitamin D dose that is necessary for achieving adequate circulating 25OHD levels in vitamin D-insufficient or vitamin D-deficient individuals/cohorts with different body weights and ages
Purpose There is considerable variation in incremental circulating 25-hydroxyvitamin D ( 25OHD ) levels on vitamin D supplements , even when similar age groups and identical vitamin D doses are compared .
We therefore aim ed to investigate the importance of body weight for the dose – response relation in circulating 25OHD .