Thyroid
Anatomy
The thyroid gland develops from the ventral pouch of the fetal pharynx. This pouch
evolves into the thyroid gland by migrating caudally to a resting place in front of the
trachea. This migration may leave thyroid remnants along the embryonic tract which
extends from the back of the tongue. A midline thyroglossal cyst may develop if the
migration tract fails to obliterate.
The thyroid gland consists of two lateral lobes joined by an isthmus. The gland lies in
front of the larynx and trachea with the isthmus overlying the second to fourth
tracheal rings. The lateral lobes extend from the side of the thyroid cartilage to the
sixth tracheal ring. Two nerves lie in close proximity to the thyroid gland: the
recurrent laryngeal nerve runs in the groove between the trachea and the thyroid and
the external branch of the superior laryngeal nerve lies deep to the upper poles. In
thyroid cancer these nerves may be invaded and damage may occur in the course of
thyroid surgery.
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Clinical Educators
Bradford Hospitals NHS Trust
Physiology
The thyroid gland is largely composed of microscopic spherical sacs called thyroid
follicles. The wall of each follicle consists of two types of cells, most extend to the
lumen of the follicle and are called follicular cells. When the follicular cells are
inactive, their shape is low cubiodal to squamous. Under the influence of TSH
(thyroid stimulating hormone), they become cubiodal or low columnar and actively
secretory. The follicular cells produce thyroxine (tetriodothyronine) or T4 because
it contains four atoms of iodine, and triiodothyronine or T3, which contains three
atoms of iodine. Together these hormones are referred to as thyroid hormones.
A few C cells or parafollicular cells may be embedded within a follicle. They produce
the hormone calcitonin which helps regulate calcium homeostasis.
Actions of thyroid hormones
1.Regulate oxygen use and basal metabolic rate
2.Regulate cellular metabolism
3.Regulate growth and development
Conditions that increase ATP demand, trigger negative feedback mechanism and
increase the secretion of thyroid hormones include:

A cold environment

Hypoglycaemia

High altitude

Pregnancy
Clinical Educators
Bradford Hospitals NHS Trust
Definition of common terms
Cretinism
A syndrome associated with congenital (untreated) hypothyroidism
Signs/symptoms  dwarfism,
 mental retardation, and
 courseness of the skin and facial features

Congenital Hypothyroidism
 Congenital absence
 Inborn errors of thyroxine metabolism
Acquired hypothyroidism
 Iodine deficiency
 Autoimmune thyroiditis (Hashimoto’s disease)
 Postradiotherpy for hypertension
 Post surgical thyroidectomy
 Antithyroid drugs
 Pituitary tumors and granulomas
Clinical Educators
Bradford Hospitals NHS Trust
Taking a Thyroid History
Presenting complaint
Hyperthyroidism

Weight ↓ appetite ↑

Irritable/anxious

Frequent stools/diarrhoea

Oligomenorrhoea

Heat intolerance/sweating

Lump in neck

Tremor

Sore, dry eyes/altered appearance

Swollen legs/feet

Dyspnoea/palpitations

Muscle Weakness

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








Hypothyroidism
Weight↑ appetite ↓
Tiredness/Lethargy
Constipation
Menorrhagia
Cold intolerance
Lump in neck
Hoarse voice
Swelling (generalised)
Confusion/dementia
Hair loss
History of Presenting Complaint
 Onset of presenting complaint
 Associated symptoms (See above)
 Timing
 Exacerbating / relieving factors
 Severity
Past Medical History
 Previous thyroid problems
 Autoimmune disorders (e.g. Grave’s and Hashimoto’s both associated with
IDDM and pernicious anaemia)
 Surgical thyroidectomy
 Radioiodine therapy for hyperthyroidism
 Congenital absence of thyroid gland
 Congenital hyperthyroidism
 Increased cholesterol -Hyperlipidaemia (associated with Hypo)
 Hyper/hypotension
 Endocrine problems (pituitary, hypothalamus problems)
 Iodine deficiency
 JADE, TAB, MARCH (AF, Dyspnoea – Graves, Cystic fibrosis, Cirrhosis
associated with Hypo – Rare)
 Pregnancy – postnatal thyroiditis (associated with development of both hypo
and hyper)
Drug History
ALLERGIES
 Thyroxine (can precipitate Angina in elderly or those with coronary artery
disease therefore use cautiously)
 Propranolol (drug of choice in treatment of symptoms of Grave’s disease)
Clinical Educators
Bradford Hospitals NHS Trust


Iodine (for deficiency, treatment of goitre in insulin deficient hypothyroidism)
Antithyroid drugs such as Carbimazole (if inappropriately high doses are used
may lead to hypothyroidism, will also signify diagnosed thyroid disorder)
Social history
 Depression (associated with hypothyroidism)
 Anxiety (associated with hyperthyroidism)
 Occupation (exposure to radiation)
 Drug abuse (can lead to thyroid disorders)
 Diet (iodine Deficiency)
 Alcohol (association with cirrhosis- rare)
Family history
Thyroid disorders (inherited)
Systems review
Cardiovascular – AF, angina, atherosclerosis
Respiratory – Cystic Fibrosis,
GI/GU– Cirrhosis, Constipation, Diarrhoea, Polyuria (IDDM), Menstrual changes
Neuro – Changes to visual fields, visual acuity, eye movements
Musculoskeletal - myopathy
Clinical Educators
Bradford Hospitals NHS Trust
Thyroid examination
General inspection
Do they look ill, hypo-/hyper-thyroid?
Are they sweating or cold? Are they appropriately dressed for weather?
Pre-tibial myxoedema/Generalised Oedema (non-pitting)
Listen for a stridor.
Dyspnoea
Hoarse voice, slow speech
Anxious/irritable or depressed
Hands and Arms
Hypothyroid
Bradycardia
Cool
Dry skin
Tendon Xanthoma
Carpal Tunnel
Raynauds
Hyperthyroid
Tachycardia - Rapid/Bounding pulse
Atrial Fibrillation
Hot, sweaty
Clubbing (Graves)
Onycholysis
Fine Tremor
Systolic Hypertension
Face
Look for signs of anaemia, central cyanosis, dyspnoea as well as:
Hypothyroid
Hyperthyroid
Loss of outer eyebrow
Exophthalmos +/- ophthalmoplegia (paralysis of one
Thinning hair (women!)
or more of optic muscles) (Graves)
Xanthelasma
Lid lag
Corneal arcus/arcus senilis Lid retraction
Pale, puffy face ‘Toad-like’ Hydration
Inspection of the Neck
Obvious thyroid swelling? Look for fullness on either side of the Trachea below level
of cricoid cartiledge.
May be more distinct and easily visible.
Is the swelling bilateral or unilateral?
Is it smooth or nodular?
Does it extend behind the sternum?
Does it move on swallowing?
- Lymph nodes hardly move on swallowing.
- Thyroid will normally move upwards with contraction of pharyngeal
muscles.
- Invasive thyroid carcinoma may result in fixation of gland to surrounding
structures.
- Very large goitres may be immobilised because they occupy all available
space.
Clinical Educators
Bradford Hospitals NHS Trust
Does it move on protrusion of the tongue? - The thyroid does not, a thyroglossal cyst
will.
Inspect for any obvious lymphadenopathy
Palpation
With patient sitting palpate thyroid gland from behind. Note the following:
-
Is the swelling bilateral or unilateral?
Is the swelling hard or cystic?
Addressing these questions will help to distinguish between a solitary
nodule, a smooth goitre and a multinodular goitre.
Check central position of the trachea.
Does it move on swallowing?
Is the thyroid fixed?
Palpate the cervical lymph nodes at this point
Percussion
The student should percuss upwards over the manubrium sternum to the sternal angle
to assess for retrosternal extension.
Although this may be better assessed by palpating for the lower border of the gland
(when the patient swallows) with the neck extended, percussion is also expected!
(USS and CT are better yet.)
Auscultation
The student should listen over both lobes for a thyroid bruit.
Reflexes
Brisk reflexes – hyperthyroidism
Delayed relaxation phase with hypothyroidism – Pseudomyotonic Reflexes
Thyrotoxic myopathy – muscular weakness affecting muscles of limbs and trunk as
well as those used in speech and swallowing.
Clinical Educators
Bradford Hospitals NHS Trust
Palpation of Cervical Glands
▪ Inspect for any visible lymphadenopathy
▪ Palpate using both hands to compare sides (or one hand at a time but comparing
groups of glands with those on opposite side)
▪ From behind examine the submental, submandibular, preauricular, tonsillar, deep
cervical chain (deep to the sternocleidomastoid) in the anterior triangle of the neck.
Palpate the supra clavicular nodes and deeply for the scalene nodes.
▪ Work back up the sternocleidomastoid in the posterior triangle to examine the
posterior cervical chain, up the back of the neck and the posterior auricular and
occipital nodes.
▪ Assess the site, size, and consistency of any palpable gland. Note any tenderness
and determine if the gland is fixed to surrounding structures.
Clinical Educators
Bradford Hospitals NHS Trust
Examples of common findings
Hyperthyroidism
Hypothyroidism
Overactivity of the thyroid gland , either due to
tumor, overgrowth of the gland or graves
disease
Subnormal activity of the
thyroid gland
Diarrhoea/increased frequency
Weight , appetite 
Myopathy
Conjunctival oedema (chemosis)
Irritability / nervousness
Exopthalmosis / proptosis, arcus senilis
Dry, sore eyes
Tachycardia (AF)
Dyspnoea (goitre, AF)
Constipation
Weight , appetite 
Loss of outer third of eyebrow
Balding
Angina pectoris
Hoarse, croaky voice
Waxy, dry, flaky skin
Bradycardia
Xanthelasma (ta) and tendon
xanthoma
Effusions (pericardial/pleural)
Brisk tendon reflexes with
delayed relaxation phase
Carpal tunnel syndrome
(numbness to hands)
Cold intolerance
Spindle shaped fingers
(myxoedema)
Toad face (with myxoedema)
Periorbital puffiness
Menorrhagia
Hypotension
Goitre
Palpitations (AF)
Brisk tendon reflexes
Fine tremor
Heat intolerance
Clubbing (Graves)
Lid lag / retraction
Pretibial myxoedema (Graves)
Oligomenorrhoea
Systolic hypertension
Goitre
Hashimoto’s Disease (autoimmune hypothyroidism)
Chronic inflammation of the thyroid gland (thyroiditis) due to the formation of
antibodies against normal thyroid tissue (autoantibodies). Its features include a firm
swelling of the thyroid (goitre) and partial or total failure of secretion of thyroid
hormones; often there are autoantibodies to other organs such as the stomach (leading
malabsorption of vitamin B12 and pernicious anaemia).
Clinical Educators
Bradford Hospitals NHS Trust
Graves disease (autoimmune hyperthyroidism)
Signs/symptoms –
Diffuse goitre
Pretibial myxoedema
Finger clubbing
Oncholysis
Proptosis
Exopthalmosis
Chemosis (conjunctival oedema)
Clinical Educators
Bradford Hospitals NHS Trust