Why is my hypothyroidism not improving on Levothyroxine?

Question

Hello doctor,

My 35-year-old daughter has been dealing with hypothyroidism for three years, but her symptoms keep getting worse even though she is on Levothyroxine.

Her TSH is 8.7 mIU/L, and T4 is low at 0.9 mIU/L despite taking 125 mcg daily. She gained 35 pounds, lost half her hair, and feels exhausted all the time. also has irregular periods and trouble getting pregnant, trying for 18 months with no success.

Her endocrinologist keeps increasing thyroid medication, but levels do not improve much. tried switching to Armour Thyroid, but it made her feel jittery and anxious. The worst part is brain fog and memory problems, as she used to be sharp, but now forgets important things at work.

Also having joint pain and muscle aches that make exercise difficult. Her fertility doctor wants TSH under 2.5 mIU/L before doing IVF treatments.

Can hypothyroidism cause permanent fertility problems?
Should she get tested for other autoimmune diseases?

We worried that something else was wrong besides just the thyroid.

Please help.

Thank you.

Answer 1

Hello,

Welcome to icliniq.com.

I have read your query and can understand your concern.

Thank you for reaching out. I can understand how concerning this must feel for you, and you are right to look into it carefully.

From what you have described, this does not appear to be well-controlled hypothyroidism. A TSH of 8.7 mIU/L, along with a low free T4 (Thyroxine). Despite taking 125 mcg of medication daily, this suggests that either the dose is not sufficient for her needs or the medication is not being absorbed properly.

Levothyroxine absorption can be affected by a few common factors. It should ideally be taken on an empty stomach, with water, and there should be at least a 30 to 60 minute gap before eating. Substances like coffee, as well as supplements containing iron, calcium, magnesium, or antacids, especially if taken within four hours, can significantly reduce how well the medication works. In some cases, underlying gut conditions such as celiac disease, H. pylori infection, atrophic gastritis, or inflammatory bowel disease can also interfere with absorption.

Regarding your concern about fertility, untreated or poorly controlled hypothyroidism can affect ovulation, but it does not cause permanent infertility. The reassuring part is that once thyroid hormone levels are properly corrected, fertility usually improves. So this is very likely reversible with the right management.

To understand why her thyroid levels are not responding as expected, some additional tests would be helpful. These may include a celiac screening panel, vitamin B12, iron studies (including ferritin), vitamin D levels, and testing for H. pylori (stool antigen or breath test). It would also be important to review whether her current dose is appropriate for her weight and clinical needs.

If she is experiencing symptoms like weakness or fatigue, supplements such as iron, folic acid, calcium, and B12 may be beneficial if deficiencies are found. Symptoms like brain fog often improve once thyroid levels are brought back into the normal range.

It would also be reasonable to screen for other autoimmune conditions, as they can sometimes coexist with thyroid disorders.

The next best step would be to review her medication routine and test results with her doctor, so the dose and any underlying issues can be addressed in a structured way.

I hope this answers your query.

Please let me know if I can assist you further.

Thank you.