Clinical Thyroid Disease COPY Flashcards
what are the types of thyroid disease?
- Hypothyroidism
- Goitre
- Thyroid Cancer
- Hyperthyroidism
how does the feedback system form the thyroid gland work?
symptoms of hyperthyroid and hypothyroid are ___________
opposing
what are the symptoms of hypothyroid?
- Weight Gain
- Lethargy
- Feeling cold
- Constipation
- Heavy periods
- Dry Skin/Hair
- Bradycardia
- Slow reflexes
- Goitre
- Severe – puffy face, large tongue, hoarseness, coma
what are the symptoms of hyperthyroid?
- Weight Loss
- Anxiety/Irritability
- Heat Intolerance
- Bowel frequency
- Light periods
- Sweaty palms
- Palipitations
- Hyperreflexia/Tremors
- Goitre
- Thyroid eye symptoms/signs
how does primary (thyroid) hypothyroidism affect TSF, T4 and T3 levels?
Raised TSH, Low FT4 & FT3
how does subclinical (compensated) hypothyroidism affect TSF, T4 and T3 levels?
Raised TSH: Normal FT4 & FT3
Subclinical – the pituitary has produced enough TSH to make enough T3 and T4
Subclinical hypothyroidism is an early, mild form of hypothyroidism, a condition in which the body doesn’t produce enough thyroid hormones. It’s called subclinical because only the serum level of thyroid stimulating hormone from the front of the pituitary gland is a little bit above normal
how does secondary (pituitary) hypothyroidism affect TSF, T4 and T3 levels?
Low TSH, Low FT4 & FT3
what is the prevelance of hypothyroidism?
- Commonest endocrine condition after diabetes
- 1.9% in women
- O.1% in men
- Subclinical hypothyroidism 5%
- 10% of women over the age of 60
what are the different categories that the causes of primary hypothyroidism can come under?
congenital
acquired
what are the congenital causes of primary hypothyroidism?
Developmental:
agenesis (refers to the failure of an organ to develop during embryonic growth and development due to the absence of primordial tissue)/maldevelopment (faulty or imperfect development)
Dyshormonogenesis:
trapping/organification
Incidence of congenital hypothyroidism 1 in 3500 births - All babies screened in the UK - if not picked up early then growth retardation
what are aquired causes of primary hypothyroidsm?
Autoimmune thyroid disease (commonest) - Hashimotos/atrophic
Iatrogenic:
- postoperative/post-radioactive iodine
- External RT for head and neck cancers
- antithyroid drugs, Amiodarone, Lithium, Interferon
Chronic iodine deficiency
Post-subacute thyroiditis - Post partum thyroiditis
What are the causes of secondary/tertiary hypothyroidism?
Pituitary/hypothalamic damage:
- pituitary tumour eg tumour
- craniopharyngioma (tumour that begins near the pituitary gland)
- post pituitary surgery or radiotherapy
Describe Thyroid Hormone Secretion in hypothyroidism
what investigations can be done for hypothyroidism?
- TSH/fT4
- Autoantibodies: TPO (Thyroid peroxidase antibodies)
(FBC (MCV increased))
(Lipids (hypercholesterolaemia))
(Hyponatremia due to SIADH)
(Increased muscle enzymes, ALT, CK)
(hyperprolactinaemia)
what is the treatment of hypothyroidism?
Levothyroxine (T4) tablets
(Liothyronine (T3)) - not as good as T4 tablets
Combination of T4 & T3: no benefit in studies
Initial dose Levothyroxine 1.6mcg/kg for adults <65 years old
Titrate in 25mcg steps according to TFT
Half-life of T4 is 7 days
After stabilisation annual testing of TSH
Compliance is important
how does replacement of thyroxine after many weeks affect levels of TSH and T4?
need to wait around 6-8 weeks to see true benefits of treatment
name a feature of hypothyroidism seen on this man
baggy eyes
What is the treatment of hypothyroidism (special situations):
Ischaemic Heart disease & Adults >65 years
Start at lower dose 25mcg and increase cautiously; risk of precipitating angina
People with ischemic needs a slower starts as the medication causes a faster heart
What is the treatment of hypothyroidism (special situations):
Postpartum thyroiditis
Trial withdrawal and measure TFT’s in 6 weeks
What is the treatment of hypothyroidism (special situations):
Myxedema coma
(severe hypothyroidism leading to decreased mental status, hypothermia, and other symptoms related to slowing of function in multiple organs. It is a medical emergency with a high mortality rate)
Very rare emergency, may need IV T3 (steroid)
how do you treat subclinical hypothyroidism?
Repeat tests after 2-3 months with TPO antibodies
Consider treatment TSH >10
TSH >5 with symptoms:
- Trial of therapy for 6 months and continue if symptomatic improvement
- If not stop and annual monitoring if TPO+ or every 2 to 3 years
what may the risk of over treatment in subclincal hypothyroidism cause?
osteopenia and atrial fibrillation
(Osteopenia is when your bones are weaker than normal but not so far gone that they break easily)
how does the treatment of hypothyroidism change during pregnancy?
Increased Levothyroxine requirements during pregnancy
Optimise preconceptually
what may inadequatley treated hypothyroidism during pregnancy cause?
Inadequately treated hypothyroidism linked with increased foetal loss and Lower IQ
what should be done in a perosn with hypothyroidism when they find out they are pregnant?
Increase LT4 dose by about 25% and monitor closely
Aim to keep TSH in low normal range (<2.5mU/l) and FT4 in high normal range
Treat _________ hypothyroidism if planning pregnancy (or pregnant)
subclinical
what is goitre?
a swelling of the neck resulting from enlargement of the thyroid gland
what are the causes of goitre?
Physiological: Puberty, Pregnancy
Autoimmune: Graves’ disease, Hashimoto’s disease
Thyroiditis: Acute (de Quervain’s ), Chronic fibrotic (Reidel’s)
Iodine deficiency (endemic goitre)
Dyshormogenesis
Goitrogens
(Goitrogens are substances that disrupt the production of thyroid hormones by interfering with iodine uptake in the thyroid gland. This triggers the pituitary to release thyroid-stimulating hormone (TSH), which then promotes the growth of thyroid tissue, eventually leading to goitre)
what are the different types of goitre?
- Multinodular Goitre
- Diffuse goitre: Colloid, Simple
- Cysts
- Tumours: Adenomas, Carcinoma, Lymphoma
- Miscellaneous: Sarcoidosis, Tuberculosis
what increases the risk of malignancy in a solitary nodule thyroid
Child
Adults less than 30 or over 60 years
Previous head and neck irradiation
Pain, cervical lymphadenopathy
Do large dominant nodule of MNG also need investigation?
YES
5% chance of malignancy
How do you investigate a solitary thyroid nodule?
- Thyroid function test (solitary toxic nodule)
- Ultrasound: useful in differentiating benign vs malignant
- Fine needle aspiration (FNA)
What are the different classifications that FNA may show a solitary tyhroid nodule to be?
Thy1: Inadequate
Thy 2: Benign to Thy 5: Cancer
are levels of thyroid cancer increasing?
yes
Levels going up as a lot more people are investigating than before
what are the main types of thyroid cancer?
papillary
follicular
these are both differentiated cancers
what is papillary thyroid cancer?
Commonest
Multifocal, local spread to lymph nodes
Good prognosis
what is follicular thyroid cancer?
Usually single lesion
Metastases to lung/bone
Good prognosis if resectable
what is the management of thyroid cancer?
- Near Total Thyroidectomy
- High dose radioiodine (Ablative)
- Long term suppressive doses of thyroxine
- Followup:
- Thyroglobulin (if rises you know cancer is coming back and you need to do something about it)
- Whole body iodine scanning (following 2-4 weeks of thyroxine withdrawal or recombinant TSH injections)
what is the prognosis of thyroid cancer and what does it depend upon?
Prognosis poorer:
Age <16 or > 45, Tumour size, Spread outside thyroid capsule and metastases, TNM stage
what are other types of thyroid cancer?
anaplastic
lymphoma
what is anaplastic thyroid cancer?
<5% of thyroid cancers
Aggressive, locally invasive
Very poor prognosis, Do not respond to radioiodine; external RT may help briefly
what is a lymphoma thyroid cancer?
Rare; May arise from preexisting hashimotos thyroiditis
External RT more helpful, combined with chemotherapy
In thyroid lymphoma, the lymphocytes of the thyroid turn into cancer cells
What tumour arises from parafollicular C cells in the thyroid gland?
Medullary thyroid cancer
Unlike papillary and follicular thyroid cancers, which arise from thyroid hormone-producing cells, medullary thyroid cancer originates in the parafollicular cells (also called C cells) of the thyroid
Medullary thyroid cancer is often associated with what?
Often associated with MEN 2 (phaeochromocytoma & hyperparathyroidism)
What levels are raised in medullary thyroid cancers?
Serum calcitonin levels raised
what is the treatment and prognosis of medullary thyroid cancer?
Treatment: Total thyroidectomy. No role for radioiodine
Prognosis variable
what does radioiodine do in regards to treatment of thyroid cancers?
Radioiodine is the next stage of treatment to mop up anything after surgery
Describe Thyroid Hormone Secretion in hyperthyroidism
What is thyrotoxicosis?
Thyrotoxicosis means an excess of thyroid hormone in the body
Having this condition also means that you have a low level of thyroid stimulating hormone, TSH, in your bloodstream, because the pituitary gland senses that you have “enough” thyroid hormone
What are the primary causes of thyrotoxicosis
Grave’s disease (70%)
Toxic Multinodular Goitre (20%) - more common in older people
Toxic adenoma
What are the secondary causes of thyrotoxicosis
Pituitary adenoma secreting TSH
What are the causes of thyrotoxicosis without hyperthyroidism?
Destructive thyroiditis (post-partum, subacute [de Quervain’s], amiodarone-induced
Excessive thyroxine administration
70-80% of all cases of hyperthyroidism is caused by _____________
Grave’s Disease
is graves disease more common in males or females?
Incidence 2-3 per 1000 per year (Sex ratio 5:1)
Prevalence 1.9% female, 0.16% male
what is graves disease?
Graves’ disease is an autoimmune disorder that causes hyperthyroidism, or overactive thyroid. With this disease, your immune system attacks the thyroid and causes it to make more thyroid hormone than your body needs
graves disease is driven by what autoimmune driven conditions?
thyroid peroxidase Antibodies
TSH receptor Antibodies
review personal/family history for concurrent autoimmune disease
what antibodies are involved in graves disease?
thyroid peroxidase Antibodies
TSH receptor Antibodies
what 2 things are enough to make the diagnosis of graves disease?
hyperthyroidism
Thyroid antibodies (TSH Receptor antibodies)
what are symptoms of graves disease?
Anxiety and irritability
A fine tremor of your hands or fingers
Heat sensitivity and an increase in perspiration or warm, moist skin
Weight loss, despite normal eating habits
Enlargement of your thyroid gland (goiter)
Change in menstrual cycles
Erectile dysfunction or reduced libido
Frequent bowel movements
Bulging eyes (Graves’ ophthalmopathy)
Fatigue
Thick, red skin usually on the shins or tops of the feet (Graves’ dermopathy)
Rapid or irregular heartbeat (palpitations)
what is the most common cause of thyrotoxicosis in the elderly?
Multi-nodular goitre
How do you recognise multi-nodular goitre?
- Characteristic goitre and absence of Grave’s disease
- Will not go into spontaneous remission
What is subacute (de Quervain’s) thyroiditis?
- Generally younger patients <50 years
- Viral trigger (eg enteroviruses, coxsackie)
- Often recall painful goitre +/- fever/myalgia; ESR increased
- May require short term steroids and NSAIDs
what is the management of hyperthyroidism?
antithyroid drugs
surgery
radioiodine
(may also use beta blockers just to slow things down)
What Antithyroid Drugs (ATD) can be used?
carbimazole
propylthiouracil
how are ATD given? and what are their outcomes?
titration regimen - 50% cure and 30% hypothyroidism
block-replace - 50% cure and 30% hypothyroidism and higher side effects
what are the side effects of ATD?
Rash
Agranulocytosis - 1:500
(Agranulocytosis, also known as agranulosis or granulopenia, is an acute condition involving a severe and dangerous leukopenia (lowered white blood cell count), most commonly of neutrophils, and thus causing a neutropenia in the circulating blood)
how are ATD first used?
ATD often on 1st occasion (40% chance of being cured and off medication).
Usually titration regimen, 12-18 months
What are selected cases for long term low dose ATD?
Elderly
Cardiac complications
Unwilling for RAI
how can radioiodine be used?
Stay away from children as you carry the radioiodine with you and you will be giving them xrays
Can set off alarms at airports
Chance of causing thyroid eye disease as it stimulated the TSH antibodies that are in the system but that risk is reduced by using steroids when you think someone has a high risk of that happening
do patients normally choose ATD or RAI first?
Patients usually choose ATD before RAI
Treat with ATD (stop 4-7 days before and after) - Elderly, Risk of cardiac problems
what does of RAI is normally given? and what is the risks of it?
Usually given as high/ablative dose
70% risk of hypothyroidism - Avoided in severe eye disease
what are the levels of hormones like in subclincal hyperthyroidism?
- TSH suppressed
- Normal Free thyroid hormones
what are the concerns with Subclinical Hyperthyroidism?
Bone: decreased bone density in postmenopausal; No clear fracture data
AF: 3 fold increased risk in over 60s
what is the treatment of Subclinical Hyperthyroidism?
Treatment considered ATD/RAI if persistent especially in elderly or those with increased cardiac risk
what is a
Subclinical Hyperthyroidism
what is b
Subclinical Hypothyroidism
Compliance
what is c
Secondary Hypothyroidism
TSH: 15 (0.3-3.3)
FT4: 8 (10-25)
Diagnosis:
1: Primary Hypothyroidism
2: Secondary Hypothyroidism
3: Subclinical Hypothyroidism
1
TSH: 0.5 (0.3-3.3)
FT4: 8 (10-25)
Diagnosis:
1: Primary Hypothyroidism
2: Secondary Hypothyroidism
3: Subclinical Hypothyroidism
(TSH can be inappropiately low when in the normal range)
TSH up in subclinical
2
TSH: 15 (03-3.3)
FT4: 12 (10-25)
Diagnosis
- Primary Hypothyroidism
- Secondary Hypothyroidism
- Subclinical Hypothyroidism
3
Means T4 is normal
