10 Reasons You’re Still Feeling Hypothyroid Symptoms on Thyroid Medication—and What to Do About It

As a functional wellness nurse with over 19 years of experience, I’ve walked this path myself and now guide countless clients through it in my virtual practice at Rebalance Wellness. You’re on thyroid medication, your TSH looks “normal,” yet fatigue, brain fog, weight gain, and hair loss persist. Providers may dismiss you, but your symptoms are real. Let’s uncover the why—with evidence-based insights and actionable steps to reclaim your energy.

1. Incomplete Thyroid Panel

Conventional care relies heavily on TSH and Free T4, but these miss the full picture.

A complete panel includes:

• TSH

• Free T4

• Free T3

• Reverse T3

• TPO & Tg Antibodies
  

Action: Request this full panel and work with a functional wellness provider to understand optimal ranges. (Labs available working with Rebalance Wellness).

2. Elevated Reverse T3 Blocking Active Thyroid Hormone

Reverse T3 (RT3) is the “brake pedal” on thyroid function, competing with Free T3 at cell receptors. High-normal RT3 can cause symptoms.

Causes: Stress, overmedication, illness, adrenal strain. Chronic stress elevates cortisol, which drives T4 into Reverse T3 to conserve energy—a survival mechanism gone awry in modern life.

Action:

• Test via DUTCH (assesses cortisol + sex hormones).

• Reduce stress

• Support adrenals with adaptogens, vitamin C, or glandulars (under provider guidance).
  

3. Outdated Lab Reference Ranges

Old ranges included sick and elderly patients, skewing “normal” too wide. Focusing on optimal ranges, which are based on the levels where individuals feel their best, helps identify and treat symptoms of thyroid dysfunction.

Action: Work with a functional provider that looks at optimal ranges AND symptoms. Treat the patient, not just the lab.

4. Wrong Thyroid Medication for Your Body

Most patients are stuck on generic levothyroxine (T4-only) with fillers that trigger reactions—especially in Hashimoto’s. These fillers (e.g., gluten, cornstarch, specific dyes) can potentially trigger allergic reactions, irritate the gut lining or have absorption issues.

Other Options:

• Tirosint (cleanest synthetic T4, gel cap)

• Compounded T4 + sustained-release T3

• Natural Desiccated Thyroid (NDT)

T3 is the active hormone—“T4-only therapy ignores cellular energy needs.” NDT or T3 adds provide bioidentical support.

5. Poor T4-to-T3 Conversion

Your body must convert inactive T4 into active T3, this conversion happens mostly in the liver and the gut. Stress, nutrient gaps, gut issues, sluggish liver or meds (e.g., beta-blockers, steroids) block this.

Selenium, zinc, and adequate carbohydrate intake fuel deiodinase enzymes for conversion. Low-carb diets impair it.

Action:

• Test micronutrients

• Evaluate liver health with lab markers, evaluate gut health with GI Stool MAP.

• Work on liver and gut health to ensure adequate thyroid hormone conversion.

• Add in T3-containing therapy if needed.

  
  

6. Poor Medication Absorption

Gut inflammation, fillers, or timing sabotage uptake.

Common Culprits:

• Lactose & gluten in Synthroid/levothyroxine

• Low stomach acid (common in hypothyroidism)
  

Action:

• Switch to Tirosint or Natural Desiccated Thyroid.

• Work with a functional wellness provider to test stomach acid.

• Work with functional wellness provider to improve gut health.

  
  

7. Low Iron (Often Missed)

Iron carries oxygen and supports T3 production. Hypothyroidism causes low iron via reduced stomach acid.

Optimal Iron Labs:

• Ferritin: 70–150 ng/mL

% Saturation: 35–38% Iron deficiency mimics hypothyroidism—both cause coldness, fatigue, and slow metabolism.

Action: Test before supplementing. Use gentle iron supplement recommended by provider if deficient.

8. Untreated Hashimoto’s Autoimmunity

90% of hypothyroidism is autoimmune. Conventional medicine says “nothing to do”—but root-cause care can induce remission.

Triggers to Address:

• Leaky gut

• Gluten (causes zonulin release in everyone)

• Infections, stress, toxins
  

Action:

• Eliminate gluten 100%.

• Heal gut with bone broth, glutamine, probiotics.

• Work with a functional practitioner to test for underlying infections, incorporate stress reduction techniques.
  

9. Nutrient Deficiencies Blocking Thyroid Function Key players:

• Selenium (converts T4 → T3; calms TPO antibodies)

• Zinc (T3 receptor sensitivity)

• Vitamin A, D, K

• Iodine (cautious—excess flares Hashimoto’s)

Action: 

• Test for nutrient deficiencies

• Food-first + targeted testing (e.g., micronutrient panel).

  
  

10. Symptoms from Co-Existing Conditions

Hypothyroidism doesn’t exist in isolation. Thyroid, adrenals, and sex hormones are a triad—optimize one, support all.

Action: 

• Work with a functional health provider to assess hormone balance.

Ready to Stop Guessing and Start Healing?

You deserve to feel like you again. At Rebalance Wellness RN, we use advanced testing (DUTCH, GI-MAP, full thyroid & lab panels) and personalized protocols to address root causes

Next Step: Book your free 15-minute discovery call .