I know this is about the USA. But the decisions over there all too often have an impact around other countries.
My own view is that the study is hopelessly naïve. It isn't just the absolute amount of levothyroxine but many other factors.
Just the other day, I posted about failure of some manufacturers to adequately clean between runs of different medicines.
We also have the issues of intolerance to some ingredients. I mean, it is almost universal that even in countries which have coloured levothyroxine tablets, the 50 microgram dosage is white - so that those who are sensitive to the dyes/pigments can avoid them.
FDA and its research take aim at thyroid association's guideline on not using levothyroxine generics
Zachary Brennan
Senior Editor
Generic drugs represent the vast majority of all drugs prescribed in the US.
But in some unique cases, the FDA acknowledges that there are doctors who are concerned about drugs with a narrow therapeutic window (i.e., as the FDA says, “drugs where small differences in dose or blood concentration may lead to serious therapeutic failures or adverse drug reactions”), and therefore may be more likely to prescribe brand-name products over generics in some cases.
But in one instance, where the American Thyroid Association (ATA) recommends that generics not be used in some instances when the thyroid hormone levothyroxine is used, the FDA is now pointing to new FDA-funded real-world research that shows how switching between generics proved to be similar to sticking with the brand-name counterpart.
Rest of article here:
Thyroid Federation International. Are you awareOf World Thyroid Awareness day last May?......
Hives, stomach issues, caffeine
my List of References recommending GP's keep TSH lower in range : feel free to add any others you have in replies. 
