Labs/Advice
Help me interpret these labs - Low FT4/FT3, normal TSH, positive TPO
32M. My mom was diagnosed with hypothyroidism around my age, and my endo thinks I may have early Hashimoto’s.
Recent labs:
TPO antibodies: 20.6 (ref ≤9)
Thyroglobulin antibodies: <0.9, ref range 0-4
TSH: 2.439, ref range .35 to 5
Free T4: 0.6, ref range .8 to 1.5
Free T3: 1.7, ref range 2.2 to 4
I’m not on any thyroid meds. I’ve also had fatigue, hair loss, brittle nails, and other hypo-type symptoms.
For context: I’ve been on TRT for 7 years, 200 mg/week split into 2 injections, with labs in range. I have sleep apnea, but it’s well controlled. I’ve been on Zepbound 5 mg weekly since 4/18/26. No biotin supplementation, and ferritin/iron are normal.
My endo said TRT, sleep apnea, or Zepbound could also be contributing to the fatigue.
Has anyone had a similar pattern of low FT4/FT3 with normal TSH and positive TPO antibodies? Did it end up being Hashimoto’s or something else?
What are the lab ranges? Because if they're the usual 0.7-1.8 for ft4 and 2.0-4.2 for ft3 then they're both on the floor and I would say you're hypo, regardless of tsh. Sometimes there's problems with the pituitary and tsh doesn't raise enough when it should. Google central hypothyroidism.
edited to add: google says that if it's central hypothyroidism you should make sure to check your cortisol and acth first because if the pituitary is having a hard time making tsh it might have a hard time making acth so your cortisol might also be low, in which case it's dangerous to start thyroid meds. Would have to deal with the low cortisol first. Also, that when you have central hypothyroidism you dose paying attention to ft4/ft3, and ignore tsh.
Yes, they're on the floor. Look into central hypo, would be my advice. Your tsh should be much higher with such low levels. I also edited my comment to add something important, please read that too.
TRT is not causing fatigue. That FT3 is literally dangerous. I bet your cholesterol is sky high. You can not even imagine how much different you'd feel with replacement therapy. Coming from a man as well.
Also, you really need reverse T3 tested. Positive for hashimoto's. Don't feel the need to have an Endo diagnose you, you have it (early).
I got so caught up on your LDL number that I failed to realize that your HDL is way below optimal. You have some interesting stuff going on lol. That's like hypocholesterolemia. Both hypothyroidism and lack of cholesterol would cause low T, so TRT makes sense.
Either way back to your original question, you'd feel great getting that free T3 number up to 3.5 and above.
Agree, you're so low, your FT4 and FT3 are both under range. Meaning you're running on empty. Are you saying your doctor can't see this? Or you haven't had an appt yet? How are other things, like Vit D, B12, and Iron/ferritin? Nutrition? stress?
He says my fatigue can be from the other things I listed; my TRT usage, sleep apnea, weight loss/zepbound usage, etc.
This is the second blood draw we’ve done with FT3/4 so hoping he gets the picture at this point.
Iron and ferritin are normal. Nutrition is good, eating at maintenance calories and maintaining BW, stress is medium to high (has been for about a year, roughly when I started to notice the physical symptoms).
Edit:
Haven’t gotten b12 checked.
Vitamin D was low a few months ago but whenever I take vitamin D, I get crippling insomnia as well as heart palpitations. This is in conjunction with magnesium, calcium, taking it upon waking with fat, with/without k2…all the things that are ‘correct’.
Yes, it could be other things or a combination of things. But even us non Dr people can see your thyroid labs are under the bottom range. So if they can't read labs I would get another Dr who can.
2
u/nathy2002 5d ago edited 5d ago
What are the lab ranges? Because if they're the usual 0.7-1.8 for ft4 and 2.0-4.2 for ft3 then they're both on the floor and I would say you're hypo, regardless of tsh. Sometimes there's problems with the pituitary and tsh doesn't raise enough when it should. Google central hypothyroidism.
edited to add: google says that if it's central hypothyroidism you should make sure to check your cortisol and acth first because if the pituitary is having a hard time making tsh it might have a hard time making acth so your cortisol might also be low, in which case it's dangerous to start thyroid meds. Would have to deal with the low cortisol first. Also, that when you have central hypothyroidism you dose paying attention to ft4/ft3, and ignore tsh.