Susie is a petite 5 ft 3 inch woman who weighs 102 lbs. Her starting 25-hydroxy vitamin D level was 42 ng/ml in summer.
Claire, on the other hands, struggles with her weight. Also at 5 ft 3 inches but weighing 221 lbs, Claire's starting vitamin D level was 23 ng/ml, also during the summer - severe deficiency.
I ask patients to supplement with vitamin D at a dose sufficient to increase 25-hydroxy vitamin D levels to 60-70 ng/ml.
For Susie, this required 1000 units. Her blood level: 67...

