Thyroid lumps and diagnosis Flashcards by Katrina Kaur

When does the first endocrine gland (thyroid) develop?

24 days

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What structure thickens to begin the development of the thyroid?

Endodermal thickening in the primordial pharynx

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What divides into two lobes?

Thyroid diverticulum

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How is the thyroid attached to the tongue?

By the thyroglossal duct

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What occurs at week 7?

Thyroglossal duct degenerates and is replaced by the pyramidal lobe in 50% of people

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Where does the thyroid gland lie anatomically?

Anterior to the 2nd/3rd tracheal ring

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What occurs are week 7?

Colloid in thyroid follicles

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Which cells make up the thyroid?

Follicular cells

Para-follicular cells

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What do follicular cells do?

produce and secrete Triiodothyronine (T3) and etraiodothyronine or Thyroxine (T4)

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What do T3 and T4 do?

Regulates metabolism of various tissues and organs

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What do para-follicular cells do?

Release calcitonin

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What is the function of calcitonin?

important hormone for maintaining Ca homeostasis

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What role does the hypothalamus play in the regulation of thyroid hormone synthesis?

Releases thyroid releasing hormone which stimulates pituitary gland

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What role does the pituitary gland play in the regulation of the thyroid hormone synthesis?

releases thyroid stimulating hormone

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Name the metabolic effects of the thyroid hormones?

Lipid and carbohydrate metabolism
• Growth
• Development (foetal and neonatal brain) • Cardiovascular system
• Central nervous system
• Gastrointestinal system
• Reproductive system
• Bone turnover

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Name the etiological classification of thyroid swellings

Simply goitre
Inflammatory
Neoplastic
Other

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What are the potential anomalies of thyroid gland development?

Persistence of thyroglossal duct results in thyroglossal cyst or fistula
• Rarely thyroid bud fails to descend to form the lingual thyroid
• May descend too far into the mediastinum to form the retrosternal goitre
• Thyroid bud may fail to divide into two resulting in absent thyroid lobe

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Name the benign causes of thyroid swellings

Multinodular goitre
Hashimoto’s thyroiditis
Cysts; colloid, simple, haemorrhagic - Follicular adenoma
Oxyphil adenoma

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Name the malignant causes of thyroid swellings

Papillary Ca
Follicular Ca
Medullary Ca
Anaplastic Ca
Primary lymphoma - Metastatic Ca

Name the types of solitary thyroid nodules

Adenoma
Cyst
Dominant nodule in a multinodular goitre
Colloid goitre
Localised form of thyroiditis
Thyroid carcinoma

What are the function symptoms (hyper/hypothyroidism)?

– Lethargy
– Weight loss/ gain
– Palpitations/bradycardia – Mood Change/swings
( Anxiety/ Depression)
– Diarrhoea/ Constipation
– Susceptibility to temperature
– Menstrual Abnormalities
– Fertility Problems
– Dry hair/skin
– Weak muscles
– Eye signs ( Exophthalmos/ Proptosis/ Puffy eyes)

What changes in structure must you look for when assessing a ‘lump’?

Lump, smooth goitre , asymmetrical – Size
– Speed of onset or growth
– Other neck lumps / lymph nodes

What are the associated symptoms?

problems with:

Breathing/ Stridor
– Pressure
– Swallowing
– Change in Voice

How should you examine a patient with a lump?

Feel from behind first
Trachea where is it?
Palpate lobes either side one at a time: symmetry and size
Ask patient to swallow Can I get below the swelling ( assess retrosternal extension)?
Lymph nodes: (lateral level II- V)

What does a thyroid function test assess?

TSH - FT4 - FT3

What antibody tests are taken?

- Anti TPO - Anti Tg - TRAb

What can be tested in the blood?

Calcitonin, FBC, ESR, Ca profile

What are the types of imaging studies used to assess thyroid swellings?

* Ultrasonography * Nuclear scintigraphy • CT * MRI * PET-CT

What can ultrasonography be useful for?

Assess size, anatomy, contents, vascularity of a nodule • Detect non palpable nodule in 63% patients and 24% additional nodules • Facilitates FNAC • Evaluate the recurrence of thyroid swelling following surgery • Assess any lymph node presence and adjacent structures in neck

What can thyroid scintigraphy be useful for?

Assess functional status of a nodule • Help guide FNAC of nodules • 5-20% of non functioning nodules malignant • Functioning nodules nearly always benign • Patients with suppressed TSH, presence of a functioning nodules obviates the need for biopsy • Helps detect ectopic thyroid tissue • Helps detect metastases in thyroid cancer

How does thyroid scintigraphy work?

Uses Technetium pertechnetate or radioiodine (I-131 or I-123) • Thyroid follicular cells trap both but organify radioiodine • Both benign and most malignant thyroid cells concentrate radiotracer < normal thyroid cells

What are the causes of hypo-functioning nodules on thyroid scan?

* Cyst * Non functioning adenoma • MNG * Malignancy * Thyroidits * Fibrosis

What are the causes of functioning nodules on thyroid scans?

* Adenoma * MNG * Malignancy

What are the limitations of scintigraphy?

- poor anatomy - no measurements obtained - interference by extraneous agents resulting in false negatives - unable to distinguish between benign and malignant lesions

What are CT/MRI/PET-CT scans useful for?

* Useful in assessing large goitres and their retrosternal extension * Evaluate the relationship of thyroid swelling to other neck structures * Assess lymph node status in malignant thyroid swellings * Help in the evaluation of detecting recurrent thyroid cancers

What is FNAC?

Fine needle aspiration cytology

What are the limitations of FNAC?

• Sampling errors • Cannot distinguish between follicular adenoma and carcinoma • False negatives

How is goitre/nodule treated?

* Conservative – Reassure – Benign/ Euthyroid/ asymptomatic/ no compression symptoms * Surgery – tracheal compression/ compressive symptoms/ indeterminate FNA/ Malignant FNA ( +/- Lymph node Surgery)

How is thyrotoxicosis treated?

``` • Antithyroid medication – Carbimazole – Propylthiouracil – Steroids – Betablockers • Radioactive Iodine – 131 Iodine – Definitive treatment for thyrotoxicosis – recurrent or solitary toxic nodule or toxic MNG – 80% cure one dose/90% cure two doses – 3-4 weeks away from children – No pregnancy for 6 months – Can worsen eye signs ( steroids) ```

What are the indications for the surgical treatment for thyrotoxicosis (excess thyroid hormone) ?

Recurrent / Uncontrolled Thyrotoxicosis Solitary Toxic Nodule Eye disease Preganancy Cosmetic Failed Radioiodine treatment Endocrinologists Patient choice

Name the types of thyroid surgery

• Near Total Thyroidectomy ( thyrotoxicosis) • Lobectomy/ Hemithyroidectomy/ Isthmusectomy ( nodule/ diagnostic) • Total thyroidectomy ( thyroid cancer) • Lymph Node Surgery – Central Neck Dissection ( Level VI- VII) – Lateral Neck Dissection ( Level II-V)

How is thyroid cancer treated?

* Surgery * Radioiodine Ablation • TSH suppression * Radiotherapy * Anti cancer drugs

What type of gland is the thyroid?

endocrine

Which hormones does the thyroid secrete?

a) Triiodothyronine | b) Thyroxine

What is the thyroid gland primarily responsible for regulating?

Metabolism

Are men or women more likely to be affected by thyroid swellings?

Women