Toxic – associated with hyperthyroidism Nontoxic – associated with euthyroidism Hypothyroid – commonly seen in Hashimoto’s thyroiditis

Thyroid nodules/hyperthyroid Flashcards by Leslie Mancini

Thyroid Nodules

General

Disordered growth ofthyroid cells that form a lump or amass
Discrete nodule or a multinodular goiter

Extremely common
Palpated by the patient or clinician or discovered incidentally on imaging studies

Palpable nodule in 4-7% of adults in the United States
90% are benign adenoma, colloid nodules, or cysts
Primary thyroid malignancy
Metastatic malignancy

Prevalence increases with age
♀>♂

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thyroid nodule

Individuals Risk for Malignant nodules(6)

Male
Young age (< 30 years old)
History of head-neck radiation
Family history of thyroid cancer
Personal history of another malignancy
Large, firm, solid solitary nodule or “cold” nodule
Associated cervical lymphadenopathy

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thyroid nodules

Clin Man

Asymptomatic

Symptoms:
Nodule or multinodular goiter that is visible
Anterior neck discomfort
Hoarseness
Dysphagia
Ipsilateral recurrent laryngeal nerve palsy
Hypothyroidism
Hyperthyroidism

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thyroid nodule

incidental finding

Thyroidnodules often present as an incidental finding on radiologic tests obtained for different purposes:
Carotid ultrasound
Neckor chest CT
PET

No symptoms or observable lesion by exam → thyroid cancer needs to be ruled out

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Thyroid nodule

Whenever to do further testing

Nodule ≥ 1 cm requires further testing

Nodules < 1 cm in a patient at high risk for thyroid cancer requires further testing

All thyroid nodules should be initially evaluated with a thyroid ultrasound

Nodules ≥ 1 cm and/or high-risk patient
TSH and free T4
May be low, normal, or high
Majority of patients are euthyroid

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thyroid nodule

Ultrasound

benign and high-risk features(5)

Thyroid ultrasound
Determinesnodule size and characteristics (including adjacent structures)

Benignfeatures:
Purelycystic, without solid components

High-risk features:
Solid
Hypoechoic - indicated a solid mass of dense tissue
Microcalcifications
Irregular margins
Extrathyroidal extension

can also assess vasculature

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thyroid nodule

Radionuclide thyroid scan

Performed when TSH levels are low
Goal is to examine if the nodule is functioning
Nonfunctioning – cold nodule
Iodine uptake less than surrounding tissue
Fine-needle aspiration biopsy (FNAB)

Hyperfunctioning – hot nodule
Iodine uptake more than surrounding tissue
Likely benign

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thyroid nodule

Fine-needle Aspiration (FNA) Biopsy

indications

Best method for assessing for malignancy

Indications:
≥ 1 cm nodule and:
Elevated/normal TSH + suspicious ultrasound findings
Low TSH + suspicious ultrasound findings + cold or indeterminatenodule(s)
Largenodule ≥ 1.5 cm

Thyroidnodule of any size with risk factors:
Young age
Family historyofthyroid cancer
History ofradiation

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thryoid nodule

Tx of a Benign lesion

Repeat ultrasound every 6 months initially
Stable lesion – repeat ultrasound yearly
Repeat FNA biopsy if growth occurs
> 2 mm of growth per year – higher likelihood of malignancy

Suppression therapy with levothyroxine
Nodules < 2 cm and/or ↑ TSH
Starting dose of 50 mcg PO daily

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thyroid nodules

Other treatments for benign lesions that are greater than 3cm or toxic (hyper)

Radiofrequency ablation for lesions ≥ 3 cm

Radioiodine therapy for hyperthyroid patients with toxic thyroid adenomas or multinodular goiter

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thryoid nodule

Tx of Cancerous lesion

Total thyroidectomy

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Goiter

general

Chronic enlargement of the thyroid gland due to non-neoplastic growth
Can be an overall enlargement or irregular cell growth that forms one or more nodules

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Goiter

Types (3)

Toxic – associated with hyperthyroidism
Nontoxic – associated with euthyroidism
Hypothyroid – commonly seen in Hashimoto’s thyroiditis

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Hypothalamic-Pituitary-Thyroid Axis

Complex neuroendocrine web that determines the set point of thyroid hormone production

Negative feedback

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Production of Thyroid Hormones

Two biologically active thyroid hormones:
Tetraiodothyronine (T4 or thyroxine)
Triiodothyronine (T3)
Most metabolically active

Derived from modification of tyrosine (amnio acid)

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Hyperthyroidism

general
Typical age of onset

Excessivethyroid hormones (T4 and T3) produced and released by thethyroid gland

♀>♂
Typical age of onset is 20-40 years of age

hyperthyroid

causes

Causes:
Increased synthesis of thyroid hormones
Excessive passive release of thyroid hormones
Extrathyroidal source
Pituitary adenoma (secondary hyperthyroidism)

Toxic multinodular goiter

general
More common in?

Second most common cause of hyperthyroidism in the United States (15% of cases)
Thyroid has multiple hyperfunctioning areas
More common in elderly patients (>50 years)
More common in patients that smoke
Highest incidence is in iodine-deficient area

Graves Disease

general

Most common cause of hyperthyroidism in the United States (60-80% of cases)

Autoimmune disorder in whichantibodiesagainst thethyroid-stimulating hormones (TSH) receptors cause thethyroidgland to hyperfunction (primary hyperthyroidism)

Thyroid develops diffuse hypertrophy and hyperplasia of the follicular cells with lymphoid infiltrates (toxic goiter)

Graves Disease

RF(6)

Female
Family history of thyroid disease
Personal or family history of an autoimmune disease
Under the age of 40
Stress
Smoking

Left: normal thyroid

Right: thyroid of a patient with hyperthyroidism; irregular follicles that have decreased colloid (the fluid within the follicles that contains thyroglobulin)

Graves’ disease

Clin Man

Variable: Asymptomatic → thyroid storm

Palpitations/Tachycardia
Heat intolerance/diaphoresis (vasodilation)
Weight loss due to increased metabolic rate
Exophthalmos/preorbital edema/excessive lacrimation
Fine tremors and hyperreflexia
Diarrhea
Weakness of proximal muscles
Psychosis/anxiety
Goiter
-Graves – smooth, symmetric, nontender with a thrill or bruit on auscultation (due to increased blood flow)
Pretibial myxedema
-Swelling over the tibia with the skin assuming a peau d’orange appearance

Left, top: exophthalmos
Left, bottom: pretibial myxedema
Right: multinodular goiter

# Graves Disease` Labs TSH, t3/t4, anything else?

↓ TSH (Graves and toxic multinodular goiter) ↑ T4 and T3 ↑ thyrotropin receptor antibodies (Graves disease)

# Graves Radioactive Iodine Uptake (RAIU) and Thyroid Scan

Helps to determine the cause of hyperthyroidism Uptake is a percentage of an radioactive iodine (I-123) tracer dose taken up by the thyroid at 24 hours High uptake = Graves disease or toxic multinodular goiter Thyroid scan shows the distribution of the radiotracer Homogeneous = Graves disease Multiple areas of accumulation = toxic multinodular goiter | cant use during pregnancy

# Graves Ultrasound

Ultrasound of the thyroid gland Detect diffuse enlargement, solitary or multiple nodules, and increased vascularity of the gland Primary imaging modality used during pregnancy and lactation

# graves Beta blockers

Used to control adrenergic symptoms (palpitations, tremor, heat intolerance) Very useful in those with impending thyroid storm Propranolol (**nonselective**) Immediate release: 10-40 mg PO every 8 hours Extended release: 80-160 mg PO once daily Atenolol (**selective**) 25-100 mg PO once or twice daily **Safer for use in patients with asthma or COPD**

be prepared to pick depending on underlying issues. if someone has lung issue, use selective blocker | propanolol typically used for treating.

# graves Antithyroid medication and protocol before initiation

Inhibit oxidation and organic binding of thyroid iodide by inhibiting thyroid peroxidase Inhibiting extrathyroidal conversion of T4 → T3 Requires a baseline CBC and liver function before initiation (agranulocytosis) Monitoring - Free T4 and T3 obtained 4 weeks after initiation and every 4-8 weeks with dosage adjustments

# graves Antithyroid medications And dosages

**methimazole** (Tapazole) 10-30 mg PO QD Preferred except during the first trimester of pregnancy (birth defects) **propylthiouracil (PTU)** 100 mg PO TID **Used in the 1st trimester of pregnancy and in thyroid storm Black box warning from the FDA** (severe liver damage) - once in 2-3rd trimester then switch back to methimiazole

# graves Radioactive iodine (I-131) ablation of the thyroid

**Most common treatment in the United States** Capsule or solution of sodium iodine-131 (I-131, radioactive iodine (RAI)) taken orally I-131 concentrates in the thyroid → progressive thyroid cell destruction

# graves Radioactive iodine (I-131) ablation of the thyroid Contraindications

Contraindicated in pregnancy and breastfeeding Most patients develop permanent hypothyroidism between 2-6 months after radioactive iodine ablation and require thyroid hormone replacement

# graves Total thyroidectomy is preferred when

Preferred in patients with compressive symptoms and those with contraindications to radioactive iodine ablation or failure with antithyroid medication

# Thyroid Storm General

Rare, life-threatening emergency More unbound thyroid hormone in the blood Tissues might become more sensitive to the thyroid hormone Body might become more sensitive to catecholamines → activating the sympathetic nervous system Occurs in patients previously undiagnosed or inadequately treated for hyperthyroidism

# thryroid strom precipitating factors

Precipitating factors: major stress (surgery, childbirth), trauma, illness, taking too much thyroid hormone

# thyroid strom clin man

**Fever** Delirium Nausea and vomiting Anxiety → seizures Cardiovascular manifestations: atrial fibrillation with rapid ventricular response, **hypotension**

# thyroid storm Tx

Supportive therapy – oxygen, airway maintenance Antithyroid medication (TPU/methimazole) Propranolol to control adrenergic symptoms Oral or IV sodium iodide to decrease thyroid hormone release Glucocorticoids to block the conversion of T4 to T3 Plasmapheresis Blood plasma is removed, thyroid hormone can be removed, and the remaining plasma is returned to the patient

# Hypothalamic-Pituitary-Thyroid Axis