Hyperthyroidism in Primary Care: Fast Triage, Labs, and First Steps

Quick reminder: confirm the patient wasn’t taking biotin at the time of the lab draw—biotin can cause false labs that mimic hyperthyroidism (TSH artifactually low, T4/T3 high). Ask patients to hold biotin 48 hours before repeat testing.

Typical Lab Pattern

• TSH: low/suppressed

• Free T4 and/or T3: elevated (sometimes only T3 is high → “T3 toxicosis”)

Inverse relationship: low TSH → think hyperthyroid; confirm with FT4 and T3.

Step 1 — Rule Out Thyroid Storm (Urgent)

Scan for danger signs: fever, tachycardia, delirium/ agitation, heart failure signs, abdominal pain, N/V/D.

Use the Burch–Wartofsky Point Scale (UpToDate has a calculator).

• High scores suggest storm → ED immediately for urgent management.

• If no urgent symptoms, proceed as outpatient and loop in endocrinology.

Step 2 — Calm the Symptoms (Start Now)

Most stable outpatients feel better quickly with a beta-blocker while you sort the cause:

• Propranolol 10–40 mg q6–8h (also slightly reduces T4→T3 conversion)

• or Atenolol 25–50 mg daily (titrate to resting HR ~70–90)

• Asthma/COPD: consider metoprolol/atenolol (cardioselective) and monitor

• Avoid/use caution in decompensated heart failure, severe bradycardia

Beta-blockers are symptom control only; definitive therapy depends on the cause.

Step 3 — Figure Out the Cause

Most common: Graves’ disease. Other causes include thyroiditis (painless/postpartum/subacute), toxic adenoma/multinodular goiter, and exogenous hormone.

Order targeted tests (and referrals) to distinguish:

1. Antibodies

   • TRAb/TSI → supports Graves if positive

   • (TPO Ab is more for autoimmune hypothyroidism/Hashimoto’s)

2. Radioactive iodine uptake (RAIU) and scan (if not pregnant/lactating)

   • Diffuse high uptake → Graves

   • Focal/patchy high uptake → toxic nodule(s)

   • Low uptake → thyroiditis or exogenous hormone

3. If you/endo anticipate antithyroid meds (e.g., methimazole), get baseline CBC and LFTs.

4. Women of childbearing potential: obtain pregnancy test before RAIU or starting antithyroid therapy.

5. Ocular symptoms (grittiness, diplopia, proptosis): consider ophthalmology if Graves orbitopathy suspected.

Ultrasound is for nodules/goiter on exam—not for lab abnormalities alone.

Step 4 — Who to Refer (and When)

• All newly confirmed hyperthyroid patients: Endocrinology (timing depends on severity/availability).

• Immediate ED if concern for thyroid storm.

• Pregnancy or plans to conceive: urgent endocrine co-management.

Follow-Up & Monitoring

• After starting beta-blocker and sending work-up, plan recheck in 2–4 weeks (earlier if worsening).

• Endocrinology will guide definitive therapy: antithyroid meds (methimazole typically first-line; PTU in 1st trimester), radioiodine, or surgery, individualized to cause and patient factors.

Pearls (Save Yourself Time)

• Biotin causes false hyperthyroid pattern—always ask and repeat labs after holding.

• Postpartum thyroiditis is common; often low uptake on RAIU and self-limited (treat symptoms).

• Amiodarone and lithium can cause thyroid dysfunction in either direction—check the med list.

• Subclinical hyperthyroidism (TSH low, FT4/T3 normal): repeat in 6–12 weeks; treat if persistent in older adults, AF, osteoporosis, or TSH <0.1.

Education only; use clinical judgment and local protocols.

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