lab timing
2 interactions related to lab timing
iron + ferritin test
Recent oral or intravenous iron transiently raises serum iron and transferrin saturation (and, after IV iron, ferritin itself), so iron studies drawn too soon can be misread.
ironferritiniron studiestransferrin saturationanemialab timingiron supplementsiron deficiency
vitamin d + parathyroid hormone test
Vitamin D supplementation genuinely lowers parathyroid hormone (PTH) by raising serum calcium and active vitamin D, so a PTH test drawn after recent vitamin D can read below the patient's true untreated baseline. This is a real physiologic effect and a timing/interpretation issue, not an assay artifact or a dangerous interaction.
vitamin dparathyroid hormonepthhyperparathyroidismcalcium metabolismbone healthlab timing25-hydroxyvitamin d