Thyroid Flashcards
Taking a history for a lump in neck
Where? When was it noticed? How was it first noticed? How does it bother you? pain etc Age? Persistent hoarseness? Smoking/alcohol? Weight loss? FHx, SHx
Physical examination for neck lump
Inspection Palpation - is it soft, hard etc Percussion Auscultation Trans-illumination Flexible naso-laryngo-pharyngoscopy
any lump in neck could be lesion in oro/naso/larynx
Older patient, male, southeast asian with lump and nosebleed = most likely naso pharyngeal carcinoma
Diagnostic tests for neck lump
Panendoscopy and biopsy
Ultrasonography* main test, can use to target biopsy
CT
MRI
Radionuclide iodine scan - specialist test
Arteriography - carotid tumour
Sialography
Sialography (also termed radiosialography) is the radiographic examination of the salivary glands. It usually involves the injection of a small amount of contrast medium into the salivary duct of a single gland, followed by routine X-ray projection
Fine needle aspiration cytology
FNAC
The most useful investigation for lumps in neck
Minimally invasive
Provide cytological diagnosis and help in formulating amanagement plan
Pathologist dependent procedure
Complications: bleeding, infection, seeding of tumour
Results improved with ultrasound scan guidance
Core biopsy vs open biopsy
CORE BIOPSY More invasive Seeding of tumour Crushed tissue at the edge Mostly superceded by FNAC
OPEN BIOPSY Incisional, excisional biopsies Require anaesthesia (local / general) Seeding of tumour Essential in lymphoma Disaster in other types of tumour in head and neck
What culture and blood tests can be done if suspecting pathology in neck lump?
Differential diagnosis of neck lump
Lipoma
Common Soft Mobile Smooth edge Subcutaneous Lobulated Rarely liposarcoma Excision if symptomatic
Sebecous cyst
Common Attached to skin (cutaneous) Smooth edge Spherical Punctum (not always) Can become infected Excision if symptomatic
Benign and malignant classification of thyroid tumours
BENIGN:
Follicular cell adenoma
Hurthle cell adenoma
Teratoma
MALIGNANT: Primary -Papillary carcinoma (80%) -Follicular carcinoma (10%) -Hurthle cell carcinoma -Medullary carcinoma (5%) -Anaplastic carcinoma -Lymphoma -Sarcoma -Squamous cell carcinoma
Secondary
-Kidney, lung, colon and breast
Predisposing factors for thyroid malignancy
Prolonged stimulation by
elevated TSH
Solitary thyroid nodule
Ionizing radiation
Genetic factors
Chroic lymphocystic
thyroiditis
Presenting symptoms of thyroid tumours
Solitary thyroid nodule
Cervical lymphadenopathy
Rapidly enlarging goitre
Pain in neck
Stridor due to tracheal compression
Dysphagia due to oesophageal compression
Hoarseness due to vocal cord palsy
Distant metastasis (pulmonary, bony, liver brain)
Physical examination of thyroid tumour
mobile lower neck mass moves upwards on swallowing
Can have retrosternal extension
Consistence varies from soft, rubbery, hard
Palpate for any neck lymph nodes enlargement
Laryngoscopy for vocal cord paralysis (pre-operative check)
Investigations for thyroid tumour
Thyroid function test (T3, T4, TSH) Serum calcium and calcitonin if medullary carcinoma Ultrasound scan FNAC MRI neck Non-contrast CT scan neck and chest CXR Thyroid lobectomy for biopsy
Clinical practice: thyroglossal duct cyst
Mean age: 5 years (range 4 months to 70 years)
midline neck mass
painless, moves upwards on tongue protrusion
pain and rapid enlargement due to infection
1% thyroglossal duct carcinoma
(papillary thyroid carcinoma)
Investigations:
- FNAC
- ultrasound of thyroid
Excision of thyroglossal duct cyst and
removal of body of hyoid (Sistrunk’s
procedure)
CASE:
28 year old female
Painless midline neck lump for a few months
4x4cm mass at the level of thyrohyoid membrane
Moves upward on tongue protrusion
Investigation and diagnosis?
FNAC
Ultrasound scan of thyroid
Thyroglossal duct cyst
→ Excision of thyroglossal duct cyst with body of hyoid
bone (Sistrunk’s procedure)
Benign cervical lymphadenopathy
Tuberculous cervical lymphadenitis: mycobacterial (tuberculosis) vs atypical mycobacterial
Malignant cervical lymphadenopathy
Cervical lymphadenopathy
Branchial cyst
Parotid gland neoplasm
Submandibular gland mass
CASE: 49 years old female Painless lump in left submandibular area for 3 months, not related to eating 4cm hard mass No facial weakness
Investigations? Diagnosis?
Submandibular mass
Lymphangioma
What’s the difference between a primary, secondary and tertiary dysfunction?
Primary- end organ
Secondary- pituitary
Tertiary- hypothalamus
Main target tissues of thyroid hormone
Heart
Liver
Bone
CNS
Any enlargement of thyroid is called a
GOITRE
Diffuse vs nodular goitre
A goiter can be smooth and uniformly enlarged, called diffuse goiter, or it can be caused by one or more nodules within the gland, called nodular goiter. Nodules may be solid, filled with fluid, or partly fluid and partly solid.
Hyperthyroidism
Excess thyroid hormone production
Symptoms: Anxiety and irritability Sweating and heat intolerance Palpitations Weakness Fatigue Increased appetite and weight loss
Signs: Tachycardia Tremor Goiter Warm moist skin
What is the most common cause of hyperthyroidism?
Grave’s disease
Eye signs in Grave’s
Features of Grave’s minus eye signs
Onycholysis
Dermopathy
Acropathy
Vitiligo
Hyperthyroidism in patients older than 70
Classical signs and symptoms may be lacking
Goitre may be absent
Anorexia with wasting
AF or congestive heart failure may be predominant manifestations
What is the hallmark of hyperthyrodism?
Suppressed TSH is the hallmark of hyperthyroidism
Measurement of FT3 will be necessary in patient with C/F of hyperthyroidism
Suppressed TSH
Normal FT4
Called T3 toxicosis usually seen in MNG
In a patient with overt opthalmopathy what other testing is required?
No additional testing
in selected cases can do isotope uptake studies, thyroid USS, thyroid antibody assays
In a patient without opthalmopathy, what scan is done and why?
131I uptake scan can help to establish the cause of thyrotoxicosis
Increased uptake in hyperthyroidism
Lack of uptake in thyroiditis and iodine ingestion
In MNG it serves to define the functional characteristics of the gland
Initial investigations for hyperthyroidism
Assays of fT4, TSH
Autoantibody assays - TPO, TSH receptor
Imaging
- Ultrasound
- Nuclear medicine
Identify these thyroid gland images- what do they show?
At diagnosis all patients with hyperthyroidism should be what?
Referred to specialist
Hyperthyroidism treatments and factors to consider
Treatment
- Antithyroid drugs (ATD)
- Radioiodine (131I)
- Subtotal Thyroidectomy
Factors to consider are
- Age of the patient
- Size of the goitre
- Presence of co-existing condition
Carbimazole and pregnancy
Drugs are safe in pregnancy
Possible association of carbimazole with fetal aplasia cutis
Some physicians may substitute PTU for CMZ in pregnancy
No contraindication to breast feeding
PTU is excreted less in breast milk
Patients receiving CMZ in the dose of 20mg or less need not be changed to PTU
Treatment regimens and outcomes for hyperthyroidism
CMZ typical starting dose 15-40mg once a day
PTU the starting dose 100-600mg twice a day
Titrate treatment against serum T4 concentrations at 4-6 weeks to a maintenance dose
Follow up at 3-4 months interval
For the aim of remission treatment has to be used 12-24 months
Long term remission can be achieved in 50-60% of cases
Long term treatment with carbimazole
Long term treatment with 5-10mg CMZ is safe and is an option for patients with relapsed Graves’ disease, Toxic nodular goitre
No specific markers for long term remission.
What hyperthyroid patients are unlikely to undergo remission?
Large goitre
Positive TSH receptor antibodies
F/H of thyroid disease
Opthalmopathy
Smoking
Radio-iodine indications
Safe and appropriate treatment in nearly all types of hyperthyroidism, especially in elderly
Contraindicated in children, pregnancy and women who are breast feeding
Women of childbearing age should wait for 4 months after 131I before becoming pregnant
Should be used with caution in patients with opthalmopathy
Use prophylactic steroids and avoid hypothyroidism
Things to check with patient when prescribing radio-iodine
Patient information sheet should be supplied
Patient should sign a consent form
The amount of 131I given should be sufficient to achieve euthyroidism
In 2-3 months
Moderate rate of hypothyroidism 15-20% at 1st yr
1-3% yearly subsequently
An ablative dose of 131I with higher rate of hypothyroidism is also acceptable
In patients with hyperthyroidism and low 131I uptake what is the problem?
Thyroiditis
How is thyroiditis resolved?
Spontaneous if mild
or:
B blockers
NSAIDs
Steroids
What is subclinical hyperthyroidism?
Persistently suppressed TSH with normal FT4 and FT3 in a patient with no symptoms
What could be the reason behind high FT4, FT3 and raised TSH?
- Interference with antibody or assay
2. Resistance to thyroid hormone
Anti-thyroid antibody interference
Suspect if FT4 and FT3 assays are widely discordant with each other •
Usually evidence of thyroid autoimmunity •
Anti-T4 and anti-T3 antibodies more common in free than total thyroid hormone assays.
Determine free thyroid hormone levels by equilibrium analysis where confounding antibody is excluded by dialysis membrane •
Thyroid function can be monitored by TSH once interference confirmed
Thyroid hormone resistance
What drugs affect the thyroid?
Why does amiodrone lead to hyper and hypothyroidism?
Binds to iodine
Regular testing in patients on amiodarone which may be difficult to detect clinically
- It can result in hypothyroidism or hyperthyroidism
Testing is recommended in patients with evidence of deteriorating cardiac function or weight loss
Early specialist referral is advised in view of difficulties in interpreting biochemical abnormalities
Amiodrone related hypothyroidism
Test results for hyperthyroidism type 1 and type 2
Treatment for type 1 hyperthyroidism
Carbimazole high dose Perchlorate Lithium Radioiodine Thyroidectomy
Treatment for type 2 hyperthyroidism
Prednisolone
Carbimazole
Signs and symptoms of hypothyroidism
SIGNS: Dry scaly skin Course brittle thinning hair Bradycardia Hair loss Anemia Puffy eyes
SYMPTOMS: Fatigue Cold intolerance Depression Poor concentration Musculoskeletal aches and pains Carpal tunnel
Hypothyroidism effect on body systems
Hypothyroidism mechanism
In primary hypothyroidism, decreased production of thyroid hormones by the thyroid gland causes a compensatory increase of TSH.
Secondary hypothyroidism is caused by pituitary disorders causing decreased TSH release and decreased T3/T4 levels.
Classic features of myxoedema
Nonpitting odema Periorbital odema Hoarseness Sinus bradycardia Decrease in body temperature Delayed relaxation of ankle jerks
Hypothyroidism types
Primary hypothyroidism:
- From thyroid destruction
Central or secondary hypothyroidism:
- From deficient TSH secretion,
- Generally due to sellar lesions such as pituitary tumor or craniopharyngioma
- Infrequently is congenital
Central or tertiary hypothyroidism
- From deficient TSH stimulation above level of pituitary
- Lesions of pituitary stalk or hypothalamus
- Is much less common than secondary hypothyroidism
Investigations for hypothyroidism
Serum assays - fT4, TSH
Autoantibody assays - TPO, Thyroglobulin
Imaging
- Ultrasound
- Nuclear medicine
Laboratory investigations to confirm hypothyroidism diagnosis
Hallmark is increased TSH
It antedates a decline in FT4
Presence of antibodies will confirm autoimmune thyroiditis as the cause
Can occur in association with other autoimmune disorders, pernicious anemia or Addisons’
Mild anemia
Increased CK
Abnormal lipids with high total and LDL cholesterol
Treatment of hypothyroidism
THYROXINE- aim to normalise serum TSH concentration
always check for angina and perform ECG
Thyroxine dosage
Initial dose should normally be 50-100ug
Measurement of TSH after 6 weeks
Adjust the dose by 25-50ug
Older patients especially those with IHD, initial dose should be 25ug increased every 4 weeks by 25ug
Dose of thyroxine in patients treated for thyroid carcinomas should suppress TSH below normal<0.05
TSH values of ‘normal’ population
Lab reference range defined from values in “normal” population:
0.4 – 5.5 mU/L
Variation in thyroxine dosage- when will it need to be changed?
Once the appropriate dose is established it remains constant in most patients
In pregnancy there is need to increase the dose by at least 50ug daily to maintain normal TSH concentration
TSH should be measured in each trimester
Circumstances associated with altered T4 requirements
How does mild hypothyroidism affect pregnancy?
TSH testing recommended in 1st trimester
To maintain euthyroid state, LT4 dose may need to be increased during pregnancy
Maternal hypothyroidism during gestation may result in a variety of fetal complications
Children of women with untreated hypothyroidism during pregnancy:
- Averaged 7 points lower on IQ testing*
- Had a significant percentage (19%) of IQ 85
How to distinguish between thyroid nodules?
Serum TSH guides further management
Serum calcitonin:
- sensitive marker of C-cell hyperplasia/MTC (Medullary thyroid cancer)
- Useful in follow up of MTC
Serum thyroglobulin:
- not sensitive/specific for diagnosis or thyroid malignancy
- BUT useful in follow up of differentiated thyroid cancer
Which thyroid nodules require FNAB?
Ultrasound used for thyroid nodules
What is thyroid FNA?
A thyroid fine needle aspiration biopsy is a procedure that removes a small sample of tissue from your thyroid gland. Cells are removed through a small, hollow needle. The sample is sent to the lab for analysis.
Limitations of thyroid FNA
False negatives: (< 5% of FNA) more likely in large (>4cm) or small (<1cm) nodules
Suspicious FNA (Follicular and Hurhtle cell neoplasm): cannot distinguish benign vs malignant of hypercellular nodules by FNA alone, ALWAYS require surgical pathology for dx (up to 10 – 30% of these will be CA)
Non-diagnostic results: NEVER consider equivalent to benign, up to 10% of ND FNA will contain CA on resection
Thy classification
What 3 problems can the size of a goitre cause?
Dysphagia
Dysphonia
Dyspnoea
Types of thyroid tumours
Papillary Thyroid carcinoma
Follicular carcinoma
Anaplastic carcinoma
Medullary thyroid carcinoma
Lymphoma
27 year old female with a 8 weeks history of :
Increasing anxiety, tremor, and heat intolerance.
She has lost about 4kg weight during this time.
She has no family history of thyroid problems or autoimmune diseases.
B/L proptosis Large diffuse Goitre with bruit Tremor Pulse 120/min BP 140/60mmHg
FREE T4 58.3 pmol/L (12.0 to 22.0)
FREE T3 4.7 pmol/L (3.1 to 6.8)
TSH <0.02 mU/L ( 0.27 to 4.20)
What is the most likely diagnosis ?
Grave’s disease
has hyperthyroid symptoms, but also proptosis
What is ‘armout’?
