Hello thyroid gurus,
My father gets a rapid heartbeat at night for years now. His pulse gradually increases starting around 7pm each night, from a good resting rate of ~65 bpm up to 90-120bpm around 2am, even when he is just lying in bed. He can't sleep, and if he does, he huffs & puffs so his breathing can keep up with his heartrate.
He has secondary adrenal insufficiency and hypothyroidism due to a pituitary tumour years ago. He takes 25mg Slow Release Hydrocortisone before bed, and 100mg T4 (Levo) with 35mcg Slow Release T3 in the morning.
He's 72, eats well and maintains a good weight and fitness level. He's tried Cal / Mag, vitamin D & B supplements, and eating protein before bed. He doesn't drink coffee. His ferritin, RBC, WBC, iron and vitamin results are in range. His doctor tested his heart, no issues. His pulse is normal during the day.
His latest thyroid test results are all in range: Free T3=340 (230-420), Free T4=1.2 (.82-1.77) and Reverse T3=19 so FT3/RT3= 18 (>20) which is low. In the past his results were always low; he's mostly been hypothyroid, so yay for the test results but he's miserable because he can't sleep.
My latest theory is that the T3 he's taking at 7am is suppressing his conversion of T4 (the Levo) to T3 later in the evening? So when he has no T3 at 2am and his metabolism drops, his adrenals release adrenaline to compensate and he gets an increased heart rate to keep everything moving like it should. That explains why the heartbeat only happens at night (vs. hyperthyroid all the time), and I've read that T3 suppresses conversion.
If that sounds possible, would splitting the SR T3 dose into twice daily help, or would that further suppress the T4 to T3 conversion, so he needs to also raise his T3 and lower his T4?
Or should he move to NDT instead of the Levo/ SR T3 combo help? Does the T3 in NDT have a suppressive action like SR T3?
What about Dr. Lowe's theory that people should take 1 big dose of T3 (regular release, not slow) once a day - how does that last over the 24 hours with such a short half-life?
Does his low FT3 / RT3 point to an increase in T3 or a decrease in T4?
Sigh, finding the right thyroid balance is tricky! Thanks for your thoughts.
R for P.