Hello and Welcome to ‘Ask A Doctor’ service.
I have reviewed your query and here is my advise.
If TSH levels are higher than 5 mUi/L than the
thyroid dysfunction is a very likely cause of the
fatigue and brain fog you are experiencing. The thyroid is an important hormone in the
metabolism and effects the energy level and brain function.
It takes 6-8 weeks for TSH to come to maximal change after a dose change so in your case the dose change you had 4 weeks ago might need another 2-3 weeks to give the full effect. Sometimes some patients might need doses of 150 mcg of
Levothyroxine or higher so that their TSH goes to norm.
While you wait for the 2-3 week period to pass so you can check again your TSH you may talk with your doctor on the possibility of having other tests like CBC, ERS, fasting
glucose (or HbA1C if you are not fasting),
lipids, renal function (
creatinine and electrolytes: Ca+, Na+, Mg+, Cl-), liver function (ALT,AST, Bilirubine) which will help to do a general check and rule out other possible causes of the symptoms you are having.
Hope I have answered your query. Let me know if I can assist you further.
Kind regards,
Antoneta Zotaj, MD