I've often seen it mentioned that for people with hypothyroidism their ferritin level should be at least 70. But is that 70 ng/ml or 70 pmol/l? They are substantially different: 70 ng/ml is 157 pmol/l; 70 pmol/l is 31 ng/ml.
For example, my private blood work was measured in ng/ml and came back as 4, my NHS bloods were done a week later, the result 8 pmol/l. Which 70 should I be shooting for?