© copyright annals of internal medicine, 2012 ann int med. 157 (1): itc1-1. * for best viewing:...

© Copyright Annals of Internal Medicine, 2012Ann Int Med. 157 (1): ITC1-1.

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in the clinic

Hyperthyroidism


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Who has an elevated risk for hyperthyroidism?

Individuals with:

Diffuse or nodular goiters

Type 1 diabetes, other endocrine/ nonendocrine AI diseases

Family histories of hyperthyroidism or hypothyroidism

Medications that increase risk: Amiodarone

Alpha-interferon

Interleukin-2

Lithium

Iodide

Iodinated contrast agents in those with preexisting autoimmune or nodular thyroid disease


Should clinicians screen for hyperthyroidism?

Screen: Individuals with risk factors

High risk comorbid conditions, family Hx, medication use

Consider screening: those with other medical conditions caused or aggravated by hyperthyroidism

e.g., osteoporosis, supraventricular tachycardia, A-Fib

Screen: Women >50 years

1 in 71 have unsuspected but symptomatic hyperthyroidism or hypothyroidism responsive to Rx


If clinicians screen for hyperthyroidism, which test should they use?

Serum TSH levels

Low in both overt and subclinical hyperthyroidism

(due to negative feedback by thyroid hormone levels on pituitary gland)

Screens for both hyperthyroidism & hypothyroidism

TSH assays: standardized, accurate, widely available


CLINICAL BOTTOM LINE: Screening…

Don’t screen: general population (not cost-effective)

Do screen: those with…

Diffuse or nodular goiters Type 1 diabetes, other endocrine/ nonendocrine AI diseases Osteoporosis, supraventricular tachycardia, or A-Fib Family Hx hyperthyroidism or hypothyroidism Amiodarone, α-interferon, interleukin-2, lithium, iodide use Women > 50 years of age

Use serum TSH test


What symptoms should prompt clinicians to consider hyperthyroidism? Nervousness (frequency: 99%)

Increased sweating (91%)

Palpitations (89%) or tachycardia (82%)

Heat intolerance (89%)

Fatigue (88%)

Weight loss (85%)

Shortness of breath (75%), weakness (70%)

Leg swelling (65%)

Eye symptoms (54%)

Hyperdefecation (33%)

Menstrual irregularity (22%)

Emotional lability (30–60%)


What physical examination findings indicate possible hyperthyroidism?

Tachycardia (100% frequency)

Goiter (100%)

Skin changes (97%)

Tremor (97%)

Bruit (77%)

Eye signs (30-45%)

Atrial fibrillation (10%)

Splenomegaly (10%)

Gynecomastia (10%)


What lab tests should be used for diagnosis?

Serum TSH measurement If low: order free T4 or free T4 index (FT4I) If free T4 or FT4I not elevated: order total T3 or free T3

Radioiodine uptake (RAIU): helps determine cause

Thyroid scan: helps distinguish Graves disease, toxic multinodular goiter, toxic adenoma

If radioisotope studies contraindicated…

Blood tests: TSH-receptor antibodies; thyroid-stimulating immunoglobulins; thyroid-peroxidase antibodies; thyroglobulin; human chorionic gonadotropin; sed rate

Color Doppler US (thyroid)

Whole-body radioiodine scan


Differential Diagnosis (with radioiodine uptake )

High or Normal

• Graves disease

• Toxic multinodular goiter

• Toxic adenoma

• HCG-induced hyperthyroidism

• TSH-producing pituitary tumor

Low

• Silent thyroiditis

• Postpartum thyroiditis

• Subacute (granulomatous) thyroiditis

• Iodine-induced hyperthyroidism

• Amiodarone-induced hyperthyroidism

• Iatrogenic hyperthyroidism

• Metastatic follicular thyroid cancer

• Struma ovarii


Lab and Other Studies for Hyperthyroidism (plus indication)

TSH (suspected hyperthyroidism)

Free thyroxine FT4 (suppressed TSH)

Free triiodothyronine FT3 (suppressed TSH, normal FT4)

Thyroglobulin (suspected thyroiditis)

Erythrocyte sed rate ESR (suspected subacute thyroiditis)

TSH-receptor antibodies (euthyroid Graves ophthalmopathy; assess remission with antithyroid drug Rx in Graves disease; assess neonatal risk in pregnant patients with Graves disease)

Thyroid peroxidase antibodies (confirm Hashimoto thyroiditis and autoimmune thyroid disease; assess risk for Rx-induced thyroid dysfunction and postpartum thyroiditis

RAIU (confirmed biochemical thyrotoxicosis, if cause unclear)

Thyroid scan (confirmed biochemical thyrotoxicosis, if cause unclear)

Whole body scan (suspected struma ovarii)

Color Doppler US (type I vs. type II amiodarone-induced thyrotoxicosis)

Human chorionic gonadotropin HCG (choriocarcinoma)

Jennifer Wilson

if this slide is overkill... delete!


What alternative explanations should clinicians consider?

Infection

Sepsis

Anxiety

Depression

Chronic fatigue syndrome

Atrial fibrillation of other causes

Pheochromocytoma

TSH testing usually distinguishes these from hyperthyroidism

But serum TSH levels often low in pregnancy; hyperemesis gravidarum; euthyroid sick syndrome; central hypothyroidism; with some medications (glucocorticoids, dopamine, heparin)


When should clinicians consult an endocrinologist?

Presence of hyperthyroidism uncertain

Serum TSH level low, but T4 and T3 within reference range

TSH level normal, but T4 or T3 above reference range

Cause unclear

RAIU low or undetectable (Dx usually clear when elevated)

Uncertain or suspicious about risk for or presence of thyroid storm or Graves orbitopathy


CLINICAL BOTTOM LINE: Diagnosis…

To make diagnosis, use: History and physical exam Low serum TSH level with elevated serum levels for free T4,

FT4 I, total T3, or free T3

To identify cause, use: Clinical features RAIU and thyroid scan Additional tests (TRAb, TSI, TPO antibodies, thyroglobulin,

ESR, HCG, color Doppler US, whole-body scanning)


What nondrug therapies should clinicians recommend?

Until thyroid disease adequately controlled…

Avoid heavy physical exertion

Reduce or eliminate caffeine intake

Avoid OTC decongestants and cold remedies

Discontinue smoking

Avoid exogenous sources of iodine


How should clinicians choose and prescribe drug therapy?

Beta-adrenergic blockade

Propranolol, atenolol, metoprolol, nadolol

For symptomatic hyperthyroidism of any cause

Side effects: CHF, asthma exacerbation

Antithyroid medications

Methimazole: preferred

Propylthiouracil: alternative (in 1st trimester pregnancy, if methimazole allergy, thyroid storm); beware liver failure

Inhibit thyroid hormone synthesis, lower thyroid hormone

Use for: Graves, toxic multinodular goiter, toxic adenoma

Don’t use for: low RAIU hyperthyroidism

Agranulocytosis occurs in 0.2%-0.4%


Ancillary Therapy

Potassium iodine

Acutely reduces thyroid hormone release

Use before thyroidectomy for Graves

Don’t use before radioactive iodine therapy

Lithium

Reduces thyroid hormone release

Cholestyramine

Binds thyroid hormone in intestines

Nonsteroidal anti-inflammatory

Treats subacute thyroiditis

Glucocorticoids

For severe subacute thyroiditis


When should clinicians consider I-131 as primary therapy for hyperthyroidism?

Graves disease

Achieves remission in ≈90%

Good choice if no remission with antithyroid medications

Side effects

Hypothyroidism: in almost all patients within 3–6 months

Sialadenitis (due uptake by salivary glands)

Worsening of Graves orbitopathy

Possible small increase in thyroid cancer


When should clinicians consider I-131 as primary therapy for hyperthyroidism?

Toxic multinodular goiters & toxic adenomas

Note: Contraindicated in pregnancy!

Side effects

Hypothyroidism: 50%-75%

Worse symptoms from thyroid hormone in first 2 weeks

Thyroid storm, if severely hyperthyroid

Pretreat with β-adrenergic blockade &/or methimazole: if very symptomatic or free T4 or FT4I levels exceed upper limit of reference range more than 2-fold

Discontinue methimazole 7 days before I-13

Jennifer Wilson

clarify (unclear): "exceed upper limit of reference range more than 2-fold"


When should clinicians consider thyroidectomy as primary therapy?

High RAIU hyperthyroidism (primary therapy)

Refractory amiodarone-induced cases (primary therapy)

Most often recommended for…

Those with thyroid nodules and suspected cancer

Those who can’t tolerate or refuse alternative forms Rx

Pregnancy

Patients who don’t achieve remission with antithyroid Rx


How should clinicians monitor patients who are being treated for hyperthyroidism?

At baseline:

Perform CBC w/ differential WBC count, liver panel

Once euthyroid:

Assess clinically

Measure serum TSH every 6 to 12 months for lifetime

Monitoring differs depending on chosen treatment…


Antithyroid medications

Agranulocytosis, liver injury, vasculitis: discontinue

Fever or pharyngitis: repeat CBC with differential WBC

Symptoms of liver injury: order liver profile

Once symptoms resolved + results in reference range…

Discontinue β-adrenergic blocker + reduce antithyroid Rx

Continue clinical and lab assessments every 3–6 months

After 12-18 months reduced dose + normal TSH: ? remission

Taper or stop antithyroid Rx

Measure TRAb: normal = greater likelihood remission

No remission: consider I-131 or surgery


Radioactive iodine (I-131)

Repeat clinical and lab assessments at 1-2 months

Measure TSH and free T4 in first 1-3 months

TSH suppression may last up to 6 wks after T4 and T3 fall to normal range

Start thyroid hormone-replacement when free T4 level low or TSH elevated

Adjust dose every 6-8-weeks until TSH in desired range

Thyroidectomy

Start levothyroxine before hospital discharge

Adjust dose every 6-8 weeks until TSH in desired range


What is subclinical hyperthyroidism, and what are the indications for treatment?

Definition: Low serum TSH levels + T4 and T3 levels within reference ranges

Asymptomatic or mild symptoms

RAIU typically in reference range

Thyroid scan findings consistent with underlying cause

TSH levels often normalize w/o treatment

Treat: if TSH <0.1 mU/L or symptomatic

Consider treating: if TSH ≥0.1 mU/L but still lower than reference range


How does a clinician recognize thyroid storm?

“Thyroid crisis” exaggerated manifestations of thyrotoxicosis

Unrecognized or inadequately treated thyrotoxicosis + precipitating event (infection, trauma)

Radioiodine therapy may precipitate

Dx often based on suspicious, nonspecific clinical findings

Cardinal manifestation: fever >102° F

Other features: Tachycardia, tachypnea; nausea/vomiting, diarrhea, CNS manifestations, anemia, hyperglycemia

Elevated serum total, free T4 and T3 levels; undetectable serum TSH level

Use Thyroid Storm Scoring System


Fever ° F Score

99–99.9 5

100–100.9 10

101-101.9 15

102-102.9 20

103-103.9 25

>104 30

CNS agitation

Absent 0 0

Mild 10

Moderate 20

Severe 30

Cardiac–pulse, bpm

99–109 5

110–119 10

120–129 15

130–139 20

≥140 25

Atrial fibrillation 10

Cardiac–CHF

Absent 0

Mild (edema) 5

Moderate (rales) 10

Severe (pulm edema)

15

Thyroid Storm Scoring System (feature, score)

GI signs

Absent 0

N, V, D, Pain 10

Jaundice 20

Precipitant history

Absent 0

Present 10

Total Score<25 = unlikely25-44 = suggestive>45 = likely


How does a clinician treat thyroid storm?

1. Decrease thyroid hormone synthesis

Propylthiouracil or methimazole

2. Inhibit thyroid hormone release

Sodium iodide (IV) or potassium iodide (oral)

3. Reduce heart rate

β-blocker (esmolol, metoprolol, propranolol) or diltiazem

4. Support circulation

Glucocorticoids in stress doses

Fluids (IV), oxygen, cooling

5. Treat precipitating cause


When should patients be hospitalized?

When thyroid storm present, impending, or suspected

Prognosis with aggressive therapy ≈20% mortality (was once 100%)

Dx usually based on suspicious, nonspecific findings

Do not wait for test results on serum TSH levels: delays potentially lifesaving therapy

Also, TSH levels don’t reliably distinguish thyroid storm from uncomplicated thyrotoxicosis


When should clinicians consult an endocrinologist or ophthalmologist?

Endocrinologist

Help developing optimal management plan

Unexpected events or Rx complications

Significant Graves eye disease present

Patient is pregnant

Thyroid storm present, impending, or suspected

Some guidelines suggest co-management in all cases

Ophthalmologist

Double vision or impaired visual acuity, visual fields, color vision

Significant eye discomfort

Proptosis >22 mm or extraocular muscle dysfunction


CLINICAL BOTTOM LINE: Treatment… If RAIU high or normal: Rx usually required

Inform patients on benefits and risks and jointly decide on preferred treatment

Graves disease: antithyroid meds, I-131, thyroidectomy

Toxic multinodular goiter: I-131 or thyroidectomy

Toxic adenoma:I-131 or thyroidectomy

Before definitive treatment, use antithyroid medications to improve thyroid hormone levels

If RAIU low: treat underlying cause or monitor

Condition may be transient

© copyright annals of internal medicine, 2012 ann int med. 157 (1): itc1-1. * for best viewing:...

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