T3 Overview

Thyroid hormone (T3) plays an essential role in the normal functioning of cells and therefore excessive or low levels can cause a broad range of symptoms and clinical signs which can be identified on clinical assessment. High levels of circulating T3 significantly increases metabolism resulting in weight loss and potentiates the effects of catecholamines such as adrenaline resulting in excessive sympathetic output (e.g. tachycardia, tremor, anxiety). Low levels of circulating T3 have the opposite effect, causing weight gain, low mood, constipation, poor memory and hyporeflexia.

Gather equipment

• Stethoscope

• Glass of water

• Tendon hammer

• Piece of paper

Introduction

Wash your hands and don PPE if appropriate.

Introduce yourself to the patient including your name and role.

Confirm the patient’s name and date of birth.

Briefly explain what the examination will involve using patient-friendly language.

Gain consent to proceed with the examination.

Ask the patient to sit on a chair for the assessment.

Adequately expose the patient’s neck and upper sternum.

Ask the patient if they have any pain before proceeding with the clinical examination.

General inspection

Clinical signs

Inspect the patient, looking for clinical signs suggestive of underlying pathology:

• Weight: weight loss is typically associated with hyperthyroidism (increased metabolism), whilst weight gain is associated with hypothyroidism (decreased metabolism).

• Behaviour: anxiety and hyperactivity are associated with hyperthyroidism (due to sympathetic overactivity). Hypothyroidism is more likely to be associated with low mood.

• Clothing: may be inappropriate for the current temperature. Patients with hyperthyroidism suffer from heat intolerance whilst patients with hypothyroidism experience cold intolerance.

• Hoarse voice: caused by compression of the larynx due to thyroid gland enlargement (e.g. thyroid malignancy).

Objects and equipment

Look for objects or equipment on or around the patient that may provide useful insights into their medical history and current clinical status:

• Mobility aids: patients with hyperthyroidism can develop proximal myopathy.

• Prescriptions: prescribing charts or personal prescriptions can provide useful information about the patient’s recent medications (e.g. levothyroxine).

Hands

Inspection

Inspect the patient’s hands for peripheral stigmata of thyroid-related pathology:

• Thyroid acropachy: similar in appearance to finger clubbing but caused by periosteal phalangeal bone overgrowth secondary to Graves’ disease.

• Onycholysis: painless detachment of the nail from the nail bed associated with hyperthyroidism.

• Palmar erythema: reddening of the palms associated with hyperthyroidism, chronic liver disease and pregnancy.

Peripheral tremor

Peripheral tremor is a feature of hyperthyroidism reflecting sympathetic nervous system overactivity.

To assess for evidence of a subtle peripheral tremor:

1. Ask the patient to stretch their arms out in front of them.

2. Place a piece of paper across the back of the patient’s hands.

3. Observe for evidence of a peripheral tremor (the paper will quiver).

Radial pulse

Palpate the patient’s radial pulse, located at the radial side of the wrist, with the tips of your index and middle fingers aligned longitudinally over the course of the artery.

Once you have located the radial pulse, assess the rate and rhythm.

You can calculate the heart rate in a number of ways, including measuring for 60 seconds, measuring for 30 seconds and multiplying by 2 or measuring for 15 seconds and multiplying by 4.

For irregular rhythms, you should measure the pulse for a full 60 seconds to improve accuracy.

Abnormal heart rates and rhythms

• In healthy adults, the pulse should be between 60-100 bpm.

• A pulse <60 bpm is known as bradycardia and has a wide range of aetiologies (e.g. healthy athletic individuals, hypothyroidism, atrioventricular block, medications, sick sinus syndrome).

• A pulse of >100 bpm is known as tachycardia and also has a wide range of aetiologies (e.g. hyperthyroidism, anxiety, supraventricular tachycardia, hypovolaemia).

• An irregular rhythm is most commonly caused by atrial fibrillation which can be associated with hyperthyroidism.

Face

General inspection

Inspect the patient’s face for clinical signs suggestive of thyroid pathology:

• Dry skin: associated with hypothyroidism.

• Excessive sweating: associated with hyperthyroidism.

• Eyebrow loss: the absence of the outer third of the eyebrows is associated with hypothyroidism (although this is a rare sign).

Eyes

Inspect the eyes for evidence of eye pathology associated with thyrotoxicosis (e.g. Graves’ disease) including lid retraction, eye inflammation, exophthalmos (also known as proptosis), eye movement abnormalities and lid lag.

Lid retraction

To identify lid retraction inspect the eyes from the front and note if sclera is visible between the upper lid margin and the corneal limbus (this indicative of lid retraction).

Upper eyelid retraction is the most common ocular sign of Graves’ disease however it can be present in other thyrotoxic states (e.g. toxic multinodular goitre). Eyelid retraction is thought to occur due to sympathetic hyperactivity causing excessive contraction of the superior tarsal and levator palpebrae superioris muscles.

Exophthalmos

To identify exophthalmos, inspect the eye from the front, the side and from above.

Exophthalmos is bulging of the eye anteriorly out of the orbit. Bilateral exophthalmos develops in Graves’ disease, due to oedema and lymphocytic infiltration of orbital fat, connective tissue and extraocular muscles.

Eye inflammation

Inspect for evidence of inflammation affecting the eyes.

Due to lid retraction and exophthalmos, the eye is more prone to dryness and the development of conjunctival edema (chemosis), conjunctivitis and in severe cases corneal ulceration.

Eye movements

Assess for evidence of ophthalmoplegia (e.g. restricted eye movement, diplopia) and pain during eye movement caused by Graves’ disease (lymphocytic infiltration of orbital fat, connective tissue and extraocular muscles):

1. Ask the patient to keep their head still and follow your finger with their eyes.

2. Move your finger through the various axes of eye movement (“H” shape).

3. Observe for restriction of eye movements and ask the patient to report any double vision or pain

Lid lag

Lid lag refers to a delay in the descent of the upper eyelid in relation to the eyeball when looking downward. Lid lag is most commonly associated with Graves’ disease although it can be present in other thyrotoxic states (e.g. toxic multinodular goitre).  Lid lag is thought to occur secondary to a combination of lid retraction and exophthalmos.

To assess for evidence of lid lag:

1. Hold your finger superiorly and ask the patient to follow it with their eyes, whilst keeping their head still.

2. Move your finger in a downwards direction whilst observing the patient’s upper eyelids as the patient’s eyes follow your finger. If lid lag is present, the upper eyelids will be observed lagging behind the eyes’ downward movement, with the sclera being visible between the upper lid margin and the corneal limbus.

Thyroid inspection

General inspection

Inspect the midline of the neck from the front and the sides noting any masses (e.g. goitre) or scars (e.g. previous thyroidectomy). The normal thyroid gland should not be visible.

Further inspection of a mass

If a mass is identified during the initial inspection, perform some further assessments to try and narrow the differential diagnosis.

Swallowing

Ask the patient to swallow some water and observe the movement of the mass:

• Thyroid gland masses (e.g. a goitre) and thyroglossal cysts typically move upwards with swallowing.

• Lymph nodes will typically move very little with swallowing.

• An invasive thyroid malignancy may not move with swallowing if tethered to surrounding tissue.

Tongue protrusion

Ask the patient to protrude their tongue:

• Thyroglossal cysts will move upwards noticeably during tongue protrusion.

• Thyroid gland masses and lymph nodes will not move during tongue protrusion.

Thyroid palpation

Palpate each of the thyroid’s lobes and the isthmus:

1. Stand behind the patient and ask them to tilt their chin slightly downwards to relax the muscles of the neck to aid palpation of the thyroid gland.

2. Place the three middle fingers of each hand along the midline of the neck below the chin.

3. Locate the upper edge of the thyroid cartilage (“Adam’s apple”) with your fingers.

4. Move your fingers inferiorly until you reach the cricoid cartilage. The first two rings of the trachea are located below the cricoid cartilage and the thyroid isthmus overlies this area.

5. Palpate the thyroid isthmus using the pads of your fingers.

6. Palpate each lobe of the thyroid in turn by moving your fingers out laterally from the isthmus.

7. Ask the patient to swallow some water, whilst you feel for the symmetrical elevation of the thyroid lobes (asymmetrical elevation may suggest a unilateral thyroid mass).

8. Ask the patient to protrude their tongue (if a mass represents a thyroglossal cyst, you will feel it rise during tongue protrusion).

Characteristics of the thyroid gland

When palpating the thyroid gland, assess the following characteristics:

• Size: note if the thyroid gland feels enlarged.

• Symmetry: assess for any evidence of asymmetry between the thyroid lobes (unilateral enlargement may be caused by a thyroid nodule or malignancy).

• Consistency: assess the consistency of the thyroid gland tissue, noting any irregularities (e.g. a widespread irregular consistency would be suggestive of a multinodular goitre).

• Masses: note if there are any distinct palpable masses within the thyroid gland’s tissue (e.g. solitary thyroid nodule or thyroid malignancy).

• Palpable thrill: assess for evidence of a palpable thrill caused by increased vascularity of the thyroid gland due to hyperthyroidism (suggestive of Graves’ disease).

Characteristics of a thyroid mass

If a thyroid mass is noted assess its position, shape, consistency and mobility (i.e. is it tethered to underlying tissue).

Thyroglossal cyst

Thyroglossal cysts are the most common congenital abnormality of the neck and arise as a result of the persistence of the thyroglossal duct. The thyroglossal duct is the tract by which the thyroid gland descends during embryological development to its final position in the front of the neck. The tongue is attached to the thyroglossal duct, which is why thyroglossal cysts rise during tongue protrusion.

Types of goitre

There are several different subtypes of goitre which include:

• Diffuse goiter: the whole thyroid gland is enlarged due to hyperplasia of the thyroid tissue.

• Uninodular goiter: the presence of a single thyroid nodule which may be active (toxic) autonomously producing thyroid hormones (causing hyperthyroidism) or inactive.

• Multinodular goiter: the presence of multiple thyroid nodules which may be active or inactive. Active multinodular goiters are often referred to as toxic multinodular goiters.

Lymph node palpation

Assess for local lymphadenopathy which may indicate the metastatic spread of primary thyroid malignancy.

1. Position the patient sitting upright and examine from behind if possible. Ask the patient to tilt their chin slightly downwards to relax the muscles of the neck and aid palpation of lymph nodes. You should also ask them to relax their hands in their lap.

2. Stand behind the patient and use both hands to start palpating the neck.

3. Use the pads of the second, third and fourth fingers to press and roll the lymph nodes over the surrounding tissue to assess the various characteristics of the lymph nodes. By using both hands (one for each side) you can note any asymmetry in size, consistency and mobility of lymph nodes.

4. Start in the submental area and progress through the various lymph node chains. Any order of examination can be used, but a systematic approach will ensure no areas are missed:

• Submental

• Submandibular

• Pre-auricular

• Post-auricular

• Superficial cervical

• Deep cervical

• Posterior cervical

• Supraclavicular

Take caution when examining the anterior cervical chain that you do not compromise cerebral blood flow (due to carotid artery compression). It may be best to examine one side at a time here.

A common mistake is a “piano-playing” or “spider’s legs” technique with the fingertips over the skin rather than correctly using the pads of the second, third and fourth fingers to press and roll the lymph nodes over the surrounding tissue.

Inspection

General inspection of the face:

Agitated?, Anxious?, Fidgety?

Sweating (Hyperthyroidism)

Dry skin (Hypothyroidism)

Loss of the outer third of the eyebrow (Hypothyroidism)

Exophthalmos (Graves’ disease)

Lid retraction

General inspection of the Dorsal of the hand:

• Thyroid Acropachy (Graves’ disease)

• Peripheral tremor (Hyperthyroidism)

General inspection of the Palm of the hands:

• Palmar erythema (Hyperthyroidism)

• Dry skin (Hypothyroidism)

• Sweat (Hyperthyroidism)

General inspection of the lower limb:

• Inspect for pre-tibial myxoedema (Gravis’ disease)

Eyes

• Observe for restriction of eye movements

• Assess for lid lag

Close inspection of the neck

• Skin changes (Erythema)

• Scars (Thyroidectomy)

• Masses (Goitre - Lymphnode)

Ask the patient to drink water

• Observe for movement of any masses with swallowing

Ask the patient to protrude their tongue

Observe the movements of any masses

No movement (Thyroid gland mass / Lymph node)

Upward movement (Thyroglossal cyst)

Palpation

1. Ask the patient to flex their neck slightly forward and relax

2. Begin palpation at thyroid cartilage (Adam’s apple)

3. As you move downward you’ll reach the superior edge of the cricoid cartilage

4. Below the cricoid cartilage is the isthmus of the thyroid gland

5. Palpate the isthmus and then assess each thyroid lobe individually

6. Ask the patient to protrude their tongue (Thyroglossal cyst will rise)

7. Ask the patient to swallow and evaluate the symmetry of thyroid lobe elevation (Asymmetry may suggest a unilateral thyroid mass)

8. Palpate local lymph nodes for evidence of lymphadenopathy

9. Assess for tracheal deviation (e.g. large goiter)

Percussion

• Percuss to detect any retrosternal dullness (e.g. large goiter extending inferiorly)

Auscultation

Auscultate each lobe of the thyroid listening for a thyroid bruit (Increased vascularity secondary to Graves’ disease)

Special tests

Reflexes (Hyporeflexia = Hypothyroidism)

Assess for proximal myopathy (Hyperthyroidism)

Summary