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

A suppressed TSH with a high free T4 lands on your desk and the patient is anxious, losing weight, and their heart is racing. The first job isn't the diagnosis. It's making sure this isn't an emergency.

Here's the fast outpatient approach.

First, confirm it's real

Before anything else, make sure the patient wasn't taking biotin at the time of the draw. Biotin can produce false labs that mimic hyperthyroidism, with an artifactually low TSH and high T4/T3. Have patients hold biotin for 48 hours before repeat testing.

The typical pattern in true hyperthyroidism:

• TSH: low or suppressed
• Free T4 and/or T3: elevated. Sometimes only T3 is high, which is "T3 toxicosis."

Low TSH points to hyper. Confirm with free T4 and T3. For the full lab logic, see how to read thyroid labs fast.

Step 1: Rule out thyroid storm

Scan for danger signs first: fever, marked tachycardia, delirium or agitation, signs of heart failure, abdominal pain, and nausea, vomiting, or diarrhea.

The Burch-Wartofsky Point Scale helps quantify the risk (UpToDate has a calculator).

• A high score suggests storm. Send to the ED immediately for urgent management.
• No urgent symptoms? Proceed as an outpatient and loop in endocrinology.

Step 2: Calm the symptoms now

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

• Propranolol 10 to 40 mg every 6 to 8 hours. It also slightly reduces T4 to T3 conversion.
• Or atenolol 25 to 50 mg daily, titrated to a resting heart rate of about 70 to 90.
• Asthma or COPD: consider a cardioselective agent like metoprolol or atenolol and monitor.
• Use caution or avoid in decompensated heart failure and severe bradycardia.

A beta-blocker is symptom control only. Definitive therapy depends on the cause.

Step 3: Find the cause

The most common cause is Graves' disease. Others include thyroiditis (painless, postpartum, or subacute), a toxic adenoma or multinodular goiter, and exogenous hormone.

Order targeted tests to tell them apart:

• Antibodies. TRAb or TSI supports Graves if positive. TPO is more for autoimmune hypothyroidism and Hashimoto's.
• Radioactive iodine uptake and scan (if not pregnant or lactating). Diffuse high uptake points to Graves, focal or patchy high uptake to toxic nodules, and low uptake to thyroiditis or exogenous hormone.
• Baseline CBC and LFTs if you or endocrinology anticipate antithyroid meds like methimazole.
• Pregnancy test in women of childbearing potential before RAIU or starting antithyroid therapy.
• Ophthalmology for ocular symptoms (grittiness, double vision, proptosis) if Graves orbitopathy is suspected.

Ultrasound is for nodules or goiter on exam, not for lab abnormalities alone. For nodule workup, see thyroid nodules in primary care.

Step 4: Who to refer, and when

• All newly confirmed hyperthyroid patients go to endocrinology. Timing depends on severity and availability.
• Immediate ED if there's any concern for thyroid storm.
• Pregnancy or plans to conceive: urgent endocrine co-management.

Follow-up and monitoring

• After starting a beta-blocker and sending the workup, plan a recheck in 2 to 4 weeks, sooner if the patient is worsening.
• Endocrinology guides definitive therapy: antithyroid meds (methimazole is typically first-line, PTU in the first trimester), radioiodine, or surgery, individualized to the cause and the patient.

Pearls that save time

• Biotin causes a false hyperthyroid pattern. Always ask, and repeat the labs after holding it.
• Postpartum thyroiditis is common, often shows low uptake on RAIU, and is usually self-limited. Treat the symptoms.
• Amiodarone and lithium can cause thyroid dysfunction in either direction. Check the med list.
• Subclinical hyperthyroidism (low TSH, normal free T4 and T3): repeat in 6 to 12 weeks. Treat if it persists in older adults, atrial fibrillation, or osteoporosis, or if TSH is under 0.1.

Frequently asked questions

Can I start treatment before the cause is known?
Yes. Start a beta-blocker for symptoms in a stable outpatient while the workup is pending. Definitive therapy waits on the cause.

When does this go to the ED instead of the clinic?
Any concern for thyroid storm. Look for fever, marked tachycardia, confusion or agitation, and heart failure signs, and use the Burch-Wartofsky scale.

Do I order an uptake scan on everyone?
No. It's most useful when you need to distinguish Graves from toxic nodules from thyroiditis. Avoid it in pregnancy and lactation.

Should every hyperthyroid patient see endocrinology?
Yes, all newly confirmed cases. Pregnancy and plans to conceive warrant urgent co-management.

For the other end of the spectrum, see hypothyroidism treatment. Want this on one page at your desk? The Clinical Desk Reference is a $37 quick-reference. For the full system on working through any visit, the Primary Care Clinical Mastery Program is AANP-accredited.

Education only. Use clinical judgment and your local protocols.

Written by Allison Sowders, MSN, APRN, FNP-BC, a practicing primary care nurse practitioner and founder of Nurse Practitioner Mentor. Reviewed July 2026.