Item L carnitine biosynthesis. Public Library of Science Figshare Hi all, just a question to ask if anyone who is on Levothyroxine for underactive thyroid takes L Carnitine shots? This medication is one of the most commonly prescribed medications for thyroid dysfunction. I'm talking about levothyroxine. And while it may silence symptoms for a time, it doesn't heal the thyroidand it L Carnitine Benefits Patients with Hypothyroidism Natural Health Research Rx Item Levothyroxine 100% Powder(Non Sterile Pharmaceutical Grade ) 0.5Gm