Thyroid Basics & Screening
The best initial test to screen for thyroid dysfunction in adults
What is TSH?
Elevated TSH, low Free T4 — diagnosis?
What is primary hypothyroidism?
Clinical Note: Check anti-TPO antibodies
This is the initial treatment for overt hypothyroidism
What is levothyroxine replacement?
This is the best first test when a thyroid nodule is found.
What is a TSH?
This thyroid hormone level naturally increases during pregnancy due to elevated thyroxine-binding globulin
What is total T4 increases? (Free T4 usually remains normal).
The most common cause of hypothyroidism in the U.S.
What is Hashimoto’s thyroiditis?
Low TSH, high Free T4 — primary diagnosis AND next best step?
What is hyperthyroidism?
What is determine etiology (TSI antibodies or uptake scan?
The interval when TSH be rechecked after starting levothyroxine
What is 6-8 weeks?
Indications for thyroid ultrasound.
What are all palpable nodules, incidentally found nodules, or goiters?
This is the first-line treatment for hyperthyroidism during the first trimester of pregnancy
What is Propylthiouracil (PTU)?
(Switch to methimazole after the first trimester)
Patients that should be screened for thyroid disease according to primary care guidelines
What are adults with symptoms, women over 60, or patients with autoimmune conditions?
A low TSH and low Free T4 suggest this.
What is Central (secondary) hypothyroidism?
First-line management for symptomatic hyperthyroidism
What is a Beta Blocker?
Propranolol is first line.
Nodule >1 cm with microcalcifications — next step?
What is a Fine-needle aspiration (FNA)?
The preferred initial dose adjustment when starting levothyroxine in older adults or those with heart disease
What is 12.5–25 mcg/day?
(Otherwise, adults <60 without comorbidities, initial dose is 1.6 mcg/kg/day)
Name a drug that can cause hypothyroidism
What is amiodarone or lithium?
Elevated TSH, normal Free T4 - Primary Diagnosis?
What is subclinical hypothyroidism?
Methimazole is contraindicated in these scenarios.
What is during first trimester of pregnancy and thyroid storm?
Features that suggest malignancy on a thyroid ultrasound
What is hypoechogenicity, irregular margins, microcalcifications, taller-than-wide shape?
These cases should be referred to Endocrinology
What is pregnancy, thyroid cancer suspicion, atypical labs, or refractory symptoms?
The main reason total T4 is unreliable as a screening test
It varies with thyroxine-binding globulin levels
Which lab abnormality is seen in euthyroid sick syndrome?
Low T3, normal or low TSH and T4
Clinical Note: Occurs in severe illness or severe physical stress, absent true hypothyroid symptoms, treat underlying cause
The recommended Levothyroxine dose increase during pregnancy.
What is 20-30% increase once pregnancy is confirmed?
The most common type of thyroid cancer
What is papillary thyroid carcinoma?
This condition requires monitoring free T4 levels
What is central hypothyroidism?