Is hypothyroidism lifelong?

In most cases from Hashimoto's, yes — lifelong replacement is needed. Some causes (postpartum thyroiditis) may be temporary. Your doctor can determine if your condition is permanent.

Can hypothyroidism cause weight gain?

Yes, modest weight gain (5–10 pounds) mainly from fluid retention. Significant weight gain is usually from other factors. Proper replacement helps normalize metabolism.

When should I take thyroid medication?

Take levothyroxine on an empty stomach, ideally 30–60 minutes before breakfast or at bedtime 3+ hours after eating. Consistency in timing is important.

EndocrineICD-10: E03.9Affects about 5% of the U.S. population

Hypothyroidism

Also known as: Underactive Thyroid, Low Thyroid

Hypothyroidism occurs when the thyroid gland does not produce enough thyroid hormone, slowing metabolic processes. The most common cause is Hashimoto's thyroiditis. Symptoms develop gradually, but treatment with levothyroxine is simple, safe, and highly effective.

Symptoms

Fatigue and lethargy

Weight gain and difficulty losing weight

Increased sensitivity to cold

Constipation

Dry skin and hair loss

Puffy face and swelling

Hoarse voice

Muscle weakness and aches

Elevated cholesterol levels

Depression and memory problems

Heavy or irregular menstrual periods

Causes

Hashimoto's thyroiditis (autoimmune — most common cause)
Thyroid surgery or radioactive iodine treatment
Radiation therapy to the head or neck
Certain medications (lithium, amiodarone)
Iodine deficiency (rare in developed countries)
Pituitary gland disorders

Risk Factors

Female sex
Age over 60
Family history of thyroid disease
Autoimmune conditions
Previous thyroid surgery or radioactive iodine treatment
Pregnancy or recent delivery

Diagnosis

Blood test: elevated TSH (primary indicator)
Low free T4 confirms overt hypothyroidism
Anti-TPO antibodies to confirm Hashimoto's
Thyroid ultrasound if nodules or goiter are present

Treatment

Levothyroxine taken daily on an empty stomach
Regular TSH monitoring to adjust dosage
Combination T4/T3 therapy in select non-responders
Treatment of underlying causes when possible

Prevention

Ensure adequate iodine intake through diet
Regular thyroid screening for people with risk factors
Monitor thyroid function during and after pregnancy

When to See a Doctor

Persistent fatigue, weight gain, or cold intolerance
Dry skin, constipation, and hair loss without explanation
You are pregnant or planning pregnancy with thyroid concerns
Your thyroid medication needs adjustment

Frequently Asked Questions

Related Conditions

Hashimoto's Thyroiditis

Autoimmune

Hyperthyroidism

Endocrine

Graves' Disease

Autoimmune

Depression

Mental Health

Related from the Supplement Library

Selenium

Moderate

Mineral · Thyroid hormone metabolism (T4 to T3 conversion)

Zinc

Strong

Mineral · Immune system support and T-cell function

Vitamin D

Strong

Vitamin · Bone health and calcium absorption

Ashwagandha

Moderate

Adaptogen · Reduces cortisol and perceived stress

Iron

Strong

Mineral · Oxygen transport via hemoglobin

These supplements have been studied in relation to Hypothyroidism. Always consult your healthcare provider before starting any supplement, especially if you take medications.

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