Thyroid UK

Low Ferritin and T4


Does anyone know if an increase in levothyroxine might cause a reduction in ferritin levels? its just a thought because recent ferritin blood tests have been at the low end of normal; please see recent results below;

TSH 1.53 Range 0.30 - 5.50

Free T4 15.70 Range 7.5 - 20.00

Free T3 3.30 Range 3.80 - 6.00

Ferritin 19 Range 11 - 307 ug/l

At the time the tests were carried out 1 was taking 150mcg levo daily and in the last month my doctor has upped the levo to 200mcg daily to try and bring the free t4 optimal which is hoped will bring the free t3 up with it. I am sceptical of this approach as i think i may have a conversion problem possibly due to low vitamin levels - i am also Vit D difficient and take this as well but as we all know most GPs/Endo's will not prescribe T3.

I have to say on occasion i have felt slightly better on the increase and have even had a period which hasnt happened in years; i thought i was in perimenopause so i had thought things were improving; however the last couple of days i have felt terrible, emotional, really fatigued, very painful legs, nausea, eye strain, just generally feel out of kilter.

Would appreciate any thoughts any of you might have. i'm not due another TSH test for another couple of weeks.

5 Replies

All I can say is that my ferritin has been 600 plus,400plus and latest 600 plus on the same 125 mcg .


Lc1973, Levothyroxine dose increase won't have caused your ferritin to drop. Ferritin is optimal half way through range. It takes a long time to drop and increase. You need to supplement iron and take each tablet with 500mg-1,000mg vitamin C which will aid absorption and minimise constipation. Take iron 4 hours away from Levothyroxine.

The dose increase should increase your T4 but it's also likely to suppress your TSH which won't help stimulate T4 to T3 conversion. If T3 remains low your GP should prescribe some T3 or refer you to an endo who can. Post your new results when they are available and members will comment.


Hi Clutter

Thanks for replying. Any idea how much iron i should be taking?


Lc1973, 3 x 210mg. Ferrous Fumarate isn't as hard on the gut as Ferrous Sulphate.


Thanks Clutter.


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