• Unintentional weight loss, poor appetite tolerance, muscle weakness
• Rapid or irregular heartbeat (atrial fibrillation), palpitations
• Shortness of breath with activity, reduced exercise tolerance
• Nervousness, anxiety, sleep problems; sometimes apathy (“apathetic hyperthyroidism”)
• Frequent stools/diarrhea, heat intolerance, warm/moist skin
• Shaking hands (tremor), eye irritation or bulging with Graves’ disease

Related topics

• Atrial Fibrillation · Bone Health & Osteoporosis
• Weight Loss (Unintentional) · Anxiety

Labs

• TSH low with Free T4 and/or T3 high → hyperthyroidism
• “Subclinical”: TSH low, Free T4/T3 normal; decisions depend on age, heart/bone risk, and symptoms
• Thyroid antibodies (TRAb/TSI) support Graves’ diagnosis

Imaging

• Radioactive iodine uptake (RAIU) and scan distinguishes overproduction (high/patchy uptake) vs thyroiditis (low uptake)
• Ultrasound helps define nodules and goiter anatomy

Beta-blockers (symptom relief)

Help slow heart rate and reduce tremor/palpitations while other treatments take effect. Choice depends on heart/lung status.

Antithyroid drugs

• Methimazole is first choice for most adults
• Propylthiouracil (PTU) reserved for specific cases (e.g., early pregnancy or thyroid storm)
• Rare risks: low white count, liver injury—report fever/sore throat, dark urine, or jaundice

Radioactive iodine (RAI)

Common definitive therapy for Graves’ or toxic nodules. Many patients become hypothyroid afterward and need levothyroxine.

Surgery

Consider for large goiter, compressive symptoms, suspicious nodules, or when RAI/drugs aren’t suitable. Requires experienced surgeon.

Iodine exposures

• Limit unnecessary high-iodine supplements
• Tell your team before iodinated contrast scans—can worsen or trigger hyperthyroidism
• Amiodarone can cause over- or under-active thyroid; needs close monitoring

Antithyroid drug cautions

• Seek care urgently for fever/sore throat (possible agranulocytosis)
• Report jaundice, severe abdominal pain, dark urine (possible liver injury)

Lab checks

• Recheck TSH and Free T4 (± T3) about 4–6 weeks after starting or changing therapy
• With antithyroid drugs, periodic labs continue until stable; then extend intervals

Heart & bone health

• Pulse/blood pressure checks; rhythm monitoring if palpitations
• Bone protection after long-standing hyperthyroidism; discuss DEXA when appropriate

Energy & sleep

• Limit late-day caffeine; use calming routines to improve sleep
• Balance gentle activity with rest while symptoms improve

Eye comfort (Graves’)

• Lubricating drops, sunglasses, and head-of-bed elevation for swelling
• Stop smoking; it worsens eye disease

Safety

• Stand up slowly if light-headed; hydrate well
• Seek care for chest pain, racing heart, fever, or sudden weakness

Can hyperthyroidism cause atrial fibrillation?

Yes. Overactive thyroid increases heart irritability and can trigger AFib—especially in older adults. Treating the thyroid often helps control rhythm.

Will I need treatment forever?

It depends on the cause. Thyroiditis may resolve; Graves’ may remit on medicines, or be treated definitively with RAI or surgery.

What side effects should I watch for on methimazole?

Fever/sore throat (possible low white count) and liver symptoms (jaundice, dark urine, severe abdominal pain). Seek care urgently.

Can I take iodine supplements?

Avoid high-dose iodine unless your clinician prescribes it—excess iodine can worsen hyperthyroidism.