I'm a 32-year-old male, 78kg, vegan, experiencing cold intolerance, especially in hands and feet, psoriasis or eczema, meteorism, and fatty stools, with lab results showing elevated Thyroid-Stimulating Hormone (TSH) levels, low testosterone (Testo) 4.6 ug/L, and other hormonal imbalances, what could be the underlying cause and treatment for my symptoms?

Subclinical Hypothyroidism with Malabsorption and Dermatologic Manifestations

Primary Assessment and Diagnosis

You likely have subclinical hypothyroidism complicated by malabsorption syndrome, both potentially related to your vegan diet and underlying autoimmune processes. Your TSH of 3-4 mIU/L is in the upper-normal range, but combined with cold intolerance (especially hands and feet), psoriasis/eczema, and fatty stools, this suggests evolving thyroid dysfunction and nutrient deficiencies 1, 2.

Thyroid Dysfunction Analysis

Your presentation matches classic hypothyroidism symptoms:

• Cold intolerance is a hallmark symptom of hypothyroidism, affecting less than 1% of the population but highly specific when present 1, 2
• Cold intolerance with fatigue, dry skin (manifesting as psoriasis/eczema), and constipation (meteorism) form the classic symptom cluster 1, 3
• Your TSH of 3-4 mIU/L, while technically "normal," is at the upper limit and may represent early thyroid dysfunction, especially given your symptomatic presentation 3, 4

Critical point: TSH alone is insufficient for diagnosis in symptomatic patients. You need free T4 measurement to determine if you have subclinical hypothyroidism (high-normal TSH with low-normal T4) 1, 2.

Malabsorption Syndrome

Your fatty stools (steatorrhea) that stick to surfaces indicate fat malabsorption:

• This is NOT normal and requires investigation 3
• Vegan diets increase risk of multiple deficiencies (B12, iron, iodine, selenium, zinc) that affect thyroid function 1
• The combination of hypothyroid symptoms and malabsorption suggests possible celiac disease (despite negative blood test), inflammatory bowel disease, or pancreatic insufficiency 3

Hormonal Imbalances

Your testosterone of 4.6 μg/L (assuming ng/mL = 460 ng/dL) is low-normal to low:

• Hypothyroidism directly suppresses testosterone production 1, 4
• Low testosterone contributes to cold intolerance, fatigue, and metabolic dysfunction 1
• Your FSH of 3.4 IU/L is also low-normal, suggesting possible secondary hypogonadism related to thyroid dysfunction 1

Immediate Diagnostic Workup Required

Essential Tests (Order Now)

Thyroid panel expansion:

• Free T4 (not just TSH) - this is critical to diagnose subclinical hypothyroidism 1, 2
• Thyroid peroxidase (TPO) antibodies - to identify Hashimoto's thyroiditis, which commonly coexists with psoriasis 1, 5, 3
• Free T3 - may be low despite normal TSH in early hypothyroidism 1, 4

Malabsorption workup:

• Fecal elastase - to rule out pancreatic insufficiency causing steatorrhea 3
• Repeat celiac panel including tissue transglutaminase IgA with total IgA level (blood tests can be falsely negative) 3
• Stool studies for fat content (72-hour fecal fat collection if available) 3

Nutritional deficiencies (critical in vegans):

• Vitamin B12 level - deficiency causes neurologic symptoms and worsens hypothyroid symptoms 1, 3
• 25-hydroxyvitamin D - deficiency common in vegans and worsens autoimmune conditions 1
• Serum iron, ferritin, TIBC - iron deficiency impairs thyroid hormone metabolism 1
• Selenium level - essential for T4 to T3 conversion 1
• Iodine status (24-hour urine iodine) - vegans without iodized salt are at high risk of deficiency 1
• Zinc level - affects immune function and skin health 1

Treatment Algorithm

Step 1: Address Thyroid Dysfunction

If free T4 is low-normal with TSH 3-4 and you remain symptomatic:

• Start levothyroxine 1.5-1.8 mcg/kg/day (approximately 100-125 mcg daily for your weight) 3, 4
• At age 32 without cardiac disease, full replacement dosing is appropriate 1, 3
• Recheck TSH and free T4 in 6-8 weeks, adjust dose to achieve TSH 0.5-2.5 mIU/L 3, 4
• Cold intolerance should improve within 2-3 months of achieving euthyroidism 6

Important caveat: If you have both adrenal insufficiency and hypothyroidism (check morning cortisol if fatigue is severe), steroids must be started BEFORE thyroid hormone to avoid adrenal crisis 1.

Step 2: Treat Malabsorption

For steatorrhea:

• If fecal elastase is low, start pancreatic enzyme replacement with meals 3
• If celiac disease is confirmed on repeat testing or endoscopy, strict gluten-free diet is mandatory 3
• Consider small bowel imaging or endoscopy if steatorrhea persists despite initial workup 3

Step 3: Nutritional Repletion (Critical for Vegans)

Immediate supplementation while awaiting lab results:

• Vitamin B12: 1000 mcg daily (sublingual or IM if severe deficiency) 1
• Vitamin D3: 2000-4000 IU daily 1
• Iodine: 150 mcg daily (use iodized salt or kelp supplement) - essential for thyroid hormone synthesis 1
• Selenium: 200 mcg daily - required for T4 to T3 conversion 1
• Iron: 65 mg elemental iron daily if ferritin <50 ng/mL 1
• Zinc: 15-30 mg daily - helps with skin conditions and immune function 1

Critical warning: Take iron and calcium supplements at least 4 hours apart from levothyroxine, as they impair absorption 3, 4.

Step 4: Dermatologic Management

Psoriasis/eczema treatment:

• Your skin conditions may improve with thyroid hormone normalization 5, 4
• Studies show 47-59% of psoriasis patients have thyroid dysfunction, and treatment improves both conditions 5
• Continue topical treatments as prescribed by dermatology while addressing underlying thyroid and nutritional issues 5

Expected Outcomes and Timeline

With appropriate treatment:

• Cold intolerance should improve within 8-12 weeks of achieving euthyroidism 6
• Energy expenditure increases by 8-15% after thyroid hormone normalization 6
• Testosterone levels often normalize once thyroid function is restored 1, 4
• Steatorrhea should resolve within 4-8 weeks if pancreatic insufficiency or malabsorption is treated 3
• Psoriasis may improve but often requires continued dermatologic management 5

Common Pitfalls to Avoid

• Do not accept "normal" TSH as reassurance when you have classic hypothyroid symptoms - free T4 measurement is essential 2, 3, 4
• Do not ignore steatorrhea - this indicates significant malabsorption requiring investigation 3
• Do not assume vegan diet alone explains all symptoms - you likely have underlying autoimmune thyroid disease 5, 3
• Do not start thyroid hormone without checking cortisol if you have severe fatigue - risk of precipitating adrenal crisis 1
• Do not take supplements or eat within 1 hour of levothyroxine - impairs absorption 3, 4

Follow-Up Strategy

• Recheck thyroid function (TSH, free T4) in 6-8 weeks after starting levothyroxine 3, 4
• Reassess stool consistency and cold intolerance at 8-12 weeks 6
• Monitor nutritional markers every 3-6 months until normalized 1
• Consider endocrinology referral if symptoms persist despite normalized TSH 2, 3