Thyroid FAQ

Thyroid conditions generate many questions. Here are answers to some of the most frequently asked questions our patients bring to their appointments.

Can I eat before a thyroid blood test?

For a standard TSH test, fasting is not required — you can eat and drink normally. However, if you take levothyroxine, it's best to have your blood drawn before taking your morning dose, since TSH can be transiently affected by the dose. Ask your endocrinologist if you're unsure about timing.

Why does my TSH keep changing even though I haven't changed my dose?

TSH naturally has some biological variability. Factors that can cause TSH fluctuations without any change in medication include illness, significant changes in body weight, changes in when you take your medication relative to food, starting new medications or supplements, pregnancy, and laboratory assay variability. Minor fluctuations in TSH within the normal range typically don't require dose changes.

I feel better on a "dessicated thyroid" (Armour Thyroid). Should I switch?

Desiccated thyroid extract (DTE) contains both T4 and T3. Some patients report feeling better on DTE. However, the T4:T3 ratio in DTE does not match human thyroid hormone ratios, leading to supraphysiologic T3 levels that can cause palpitations, bone loss, and other effects. Current guidelines recommend levothyroxine as the standard of care. Discuss your symptoms with your endocrinologist — some patients may benefit from careful addition of a small T3 dose (liothyronine) to levothyroxine therapy.

What foods should I avoid with thyroid disease?

Goitrogens — compounds in cruciferous vegetables (broccoli, kale, cabbage) and soy — can theoretically interfere with thyroid function, but this is primarily relevant when consumed in very large quantities or in the setting of iodine deficiency. For most patients eating a balanced diet, moderate amounts of these foods are safe. Kelp and seaweed supplements, however, contain very high levels of iodine and can disrupt thyroid function — avoid these if you have thyroid disease.

Can stress cause thyroid problems?

Significant psychological stress can alter the immune system in ways that may trigger or worsen autoimmune thyroid conditions like Graves' disease and Hashimoto's in genetically predisposed individuals. However, stress alone does not "cause" thyroid disease in most people, and normal life stressors do not typically affect thyroid hormone levels directly.

Does having a thyroid condition mean I can never get pregnant?

Absolutely not. With proper treatment and monitoring, most women with thyroid disorders can have healthy pregnancies. The key is to optimize thyroid function before conception and to monitor thyroid levels closely during pregnancy (typically every 4–6 weeks in the first half). Women on levothyroxine usually need dose adjustments as soon as pregnancy is confirmed.

Can I stop taking levothyroxine if I feel fine?

Not without medical supervision. Hypothyroidism is usually a lifelong condition. Stopping levothyroxine will cause TSH to rise and thyroid hormone levels to fall, eventually causing symptoms — though this may take weeks to months. Never stop or change your thyroid medication without discussing it with your endocrinologist first.

What's the difference between a thyroid supplement and a thyroid medication?

Thyroid medications (levothyroxine, liothyronine) are FDA-approved prescription drugs with tightly regulated dosing. "Thyroid support" supplements sold over-the-counter are not regulated by the FDA and often contain thyroid hormone precursors or actual thyroid hormone extract in uncontrolled amounts — which can be dangerous. Do not use OTC thyroid supplements without medical guidance.