I am going to outline a common case of escalating dosages of levothyroxine. I beg you to ALWAYS look for binding interactions with levothyroxine when you see dose increases!
KE is a 68-year-old female with a history of GERD, anemia, osteoarthritis, hypertension, and diabetes. Her current medication list includes:
- Metformin 500 mg TID
- Ferrous sulfate 325 mg QD (podcast)
- Omeprazole 20 mg daily
- Vitamin B12 1,000 mcg daily
- Ibuprofen 200 mg BID
- Lisinopril 10 mg daily
- Levothyroxine 200 mcg daily (podcast)
- Hydrochlorothiazide 25 mg daily
- famotidine 20 mg at bedtime
Unfortunately, you don’t have access to current labs at the time of your visit, but the patient reports that her physician has been trying to get her thyroid labs back to normal. She reports that the dose of levothyroxine has been increased at least two-three times over the last year or so. She used to take 100 mcg daily a couple of years ago.
I want to offer a little advice about escalating dosages of levothyroxine. If you ever see a dose increase, it could be due to an increased biological need but you should ALWAYS look for binding interactions with supplements like iron, calcium, magnesium, etc before continuing to escalate the dose. Simply switching the timing of the supplement and/or levothyroxine can save the patient from a lot of unnecessary lab work and dose escalations.
I just saw a case like this yesterday where levothyroxine had been increased several times based upon an elevated TSH. The patient had been stable for a really long time. They were diagnosed with iron deficiency anemia and placed on iron therapy several months back and shortly thereafter, is when the dose escalation of levothyroxine was required.
Every time you see a dosage escalation of levothyroxine PLEASE take the time to review possible OTC and prescription binding interactions! If you are looking for more on drug interactions, feel free to take advantage of Audible’s FREE trial of my Drug Interaction Book (if you have never tried Audible before)!
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