Functional Medicine Approach to Autoimmune Hypothyroidism: A Case Report

Jamie Marie Punzi, ND

Jamie Marie Punzi, ND, Functional Medicine Resident, Vida Integrated Health, Kirkland, Washington, USA.

Corresponding author: Jamie Marie Punzi, ND  

E-mail: drjamiepunzi@gmail.com

Keywords: functional medicine, autoimmune hypothyroidism, autoimmune thyroiditis, Hashimoto thyroiditis

Introduction

Autoimmune thyroiditis is a chronic, immune-mediated disease of the thyroid gland. It is estimated to affect 7.5% of individuals globally, and disproportionately affects women.¹ It is diagnosed by measuring thyroid-stimulating hormone (TSH), free thyroxine (FT4), and thyroid autoantibodies, particularly thyroid peroxidase antibodies (TPOAb) and thyroglobulin antibodies (TGAb).² Levothyroxine monotherapy is the standard of care in overt hypothyroidism and is considered in select subclinical cases.² Subclinical autoimmune thyroiditis poses diagnostic and management challenges, especially in determining treatment candidacy.

Functional medicine is a systems-oriented approach to disease uniquely equipped to assess and address underlying causes of dysfunction.^3,4 This framework evaluates individual risk factors, triggers, and mediators to develop personalized treatment strategies. In autoimmune hypothyroidism, this systematic approach examines the gut-thyroid axis, micronutrient status, immune regulation, and lifestyle influences. Autoimmune thyroid disease is associated with gut dysbiosis and increased intestinal permeability, which may contribute to immune dysregulation and inflammation through mechanisms such as molecular mimicry and impaired immune tolerance.⁵

In this case, a 20-year-old female college student presented to an outpatient clinic with concerns of fatigue, polycystic ovarian syndrome, weight challenges, and a history of abnormal thyroid function on biochemical assessment. Comprehensive evaluation identified multiple modifiable contributors, including multiple nutrient deficiencies/insufficiencies, insulin resistance, and intestinal dysbiosis. A personalized, multimodal approach led to meaningful clinical improvement, illustrating the value of a systems-based approach in managing autoimmune hypothyroidism.

Case Report

Patient Main Concerns, Diagnoses, and Important Clinical Findings

At intake, the patient presented with fatigue, weight gain, mood disturbance, and chronic wrist pain. Historical thyroid function testing demonstrated fluctuating TSH levels (2.47-5.60 mIU/L) over 10 years, with prior thyroid peroxidase and thyroglobulin antibody positivity. Initial thyroid evaluation revealed mildly elevated TSH with normal FT4 and FT3, along with elevated TPOAb and TGAb (Tables 1 and 2).

Table 1. Baseline Clinical Characteristics at Intake

Abbreviations: FT3, free triiodothyronine; FT4, free thyroxine; TGAb, thyroglobulin antibody; TPOAb, thyroid peroxidase antibody; TSH, thyroid stimulating hormone.

Table 2. Thyroid, Immune, and Inflammation

^aLC/MS

Abbreviations: ANA, antinuclear antibody; CRP, c-reactive protein; FT3, free triiodothyronine; FT4, free thyroxine; TGAb, thyroglobulin antibody; TPOAb, thyroid peroxidase antibody; TSH, thyroid stimulating hormone; RT3, reverse triiodothyronine.

These findings are consistent with subclinical hypothyroidism secondary to autoimmune thyroiditis. Baseline nutrient and cardiometabolic assessments are summarized in Tables 3 and 4.

Table 3. Micronutrient

Abbreviations: B12,= vitamin b12; TIBC, total iron binding capacity; MMA, methylmalonic acid

Table 4. Cardiometabolic

Abbreviations: HDL-C, high-density lipoprotein; HOMA-IR, homeostatic model assessment for insulin resistance; LDL-C, low-density lipoprotein; T Chol, total cholesterol; Tg, triglycerides

Anthropometric assessment through dual-energy X-ray absorptiometry (DXA) was obtained before tirzepatide initiation to evaluate lean mass and adipose distribution, given the metabolic implications in thyroid dysfunction^6,7 and the potential for lean tissue loss during weight reduction⁸ (Table 5). Stool analysis findings are summarized in Table 6.

Table 5. Anthropometric

^apounds

Abbreviations: Total BF %, total body fat percentage; VAT, visceral adipose tissue

Table 6. Stool Analysis Findings

Interventions and Outcomes

The multimodal treatment plan included micronutrient repletion, tirzepatide, levothyroxine, nutrition counseling, and a targeted gut-directed protocol. Interventions were introduced sequentially, adjusted according to clinical and laboratory response, and delivered within a strong therapeutic alliance. Care was individualized to align with the patient’s lifestyle, preferences, and real-world constraints, including limited kitchen access, frequent travel, and a desire to engage in local cuisine without excessive restriction. Pharmaceutical and nutraceutical therapies were selected collaboratively to align with patient values, promote flexibility and long-term sustainability, and address the multifactorial drivers of her clinical presentation.

At baseline, treatment prioritized nutritional optimization and correction of iron deficiency, a modifiable factor in autoimmune thyroid disease, given the heme-dependent role of TPO in thyroid hormone synthesis. Iron deficiency impairs TPO activity and is associated with elevated TPOAb.^9,10 Counseling emphasized dietary iron sources and absorption strategies, along with selenium-rich foods. The patient initiated oral iron with vitamin C, methylfolate, and methylcobalamin every other night, in addition to daily myo-inositol. Selenium supports thyroid hormone metabolism and has been associated with reductions in TPOAb and TSH,¹¹ while myo-inositol improves TSH signaling and exerts immunomodulatory effects, with combination therapy linked to reductions in TSH and thyroid autoantibodies.^12,13 After six weeks, fatigue and red blood cell indices demonstrated mild improvement but remained consistent with iron deficiency, prompting escalation to intravenous iron sucrose infusions.¹⁴ The patient received one infusion at two months and two additional infusions at six months.

At two months, levothyroxine 25 mcg daily and tirzepatide 1.8 mg weekly were initiated alongside continuous glucose monitoring and nutritional counseling. The reduction of adipose-driven inflammatory burden was targeted, given its association with subclinical hypothyroidism and thyroid autoimmunity,^15,16 aligned with the patient’s expressed metabolic health goals.

At four months, an intestinal restoration protocol was initiated, including a multi-strain probiotic and a combined formula to support the integrity of the gastrointestinal barrier. The probiotic and prebiotic formulation was selected to address commensal strains identified as low or below detectable levels in stool analysis (Table 6). Probiotic therapy is associated with improvements in gut barrier integrity and function.^17,18 The combined nutraceutical included L-glutamine and zinc, both associated with improvements in intestinal permeability markers.^19,20 Counseling on a structured elimination diet was provided to identify dietary contributors to immune dysfunction²¹ but was deferred due to environmental constraints.

At six months, TSH became suppressed, coinciding with reductions in total body weight and improvements in cardiometabolic indices. Reportedly, improved insulin sensitivity can enhance levothyroxine efficacy, and weight loss can alter levothyroxine requirements^.22,23

At seven months, iron studies continued to improve, although ferritin was markedly elevated, likely reflecting recent intercurrent illness. By nine months, the patient reported continued improvements in energy.

By twelve months, thyroid autoantibodies, inflammatory markers, and metabolic parameters showed significant improvement from baseline. However, persistent downward trends in micronutrient indices prompted a referral to gastroenterology to evaluate for additional causes of malabsorption.

Conclusion

This case underscores the importance of addressing upstream contributors, including nutrient deficiencies, metabolic dysregulation, and gut dysbiosis, in the management of autoimmune subclinical hypothyroidism. Improvements in fatigue and body composition occurred despite dynamic thyroidal and metabolic physiology. Thyroid function normalized early but demonstrated mid-course fluctuations temporally associated with pharmacologic dose modifications, body recomposition, and intercurrent illness. Continued follow-up is needed to assess long-term stability. These findings suggest that integrating systems-based interventions and pharmacologic interventions may enhance patient-centered outcomes in autoimmune thyroid disease.

Informed Consent Statement

The patient provided written informed consent for publication of this case report. All identifying information has been removed to protect patient confidentiality.

Funding

No funding was received for the preparation of this case report.

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