Thyroid Disorders COPY Flashcards
`How does hypothyroidism present?
- Weight Gain
- Cold intolerance
- Brittle nails, thin/dry skin & hair
- Hyporeflexia, slow speech
- Lethargy & low mood
- Constipation
- Bradycardia
- Heavy periods
Severe cases can cause puffy face, large tongue, hoarseness and coma
How does hyperthyroidism present?
- Weight loss
- Heat intolerance
- Muscle weakness
- Hyperreflexia
- Frequent bowel movements
- Palpitations
- Light periods
- Sweaty palms
- Thyroid eye symptoms (bulging)
- Anxiety/irritibility
- Thick skin over shins
- Non-pitting oedema
How does gender affect thyroid disease?
Both hyper and hypothyroidism are much more common in women
What are the types of Hypothyroidism?
Primary
Subclinical
Secondary
What causes congenital Hypothyroidism?
- developmental problems e.g. agenesis
- Dyshormogenensis (autosomal recessive condition preventing TH production)
What causes acquired Primary Hypothyroidism?
- Autoimmune (hashimoto’s) thyroiditis
- Iatrogenic
- Chronic Iodine Deficiency
- Post-subacute thyroiditis
What can cause secondary or tertiary hypothyroidism?
- Pituitary tumours
- Craniopharyngioma
- Pituitary surgery/radiotherapy
- Sheehan’s Syndrome
- Isolated TRH deficiency
What is Sheehan’s Syndrome?
Post-partum ischaemic necrosis of the pituitary due to blood loss/hypovolaemic shock of childbirth
Its a potential cause of secondary hypothyroidism
List some iatrogenic causes of primary hypothyroidism?
Post op
Radioactive Iodine or Anti-Thyroids
Amiodarone (Sub-acute thyroiditis)
RT for H/N cancer
What tests would you run for suspected hypothyroidism?
- TFTs i.e. TSH & fT4
- Thyroid Peroxidase Antibodies
- FBC
- Lipids
- Serum Na+
- Muscle enzymes, ALT & CK
- Prolactin
Explain why youd do each test for hypothyroidism?
FBC - Raised MCV (RBC size)
Lipids - Hypercholesterolaemia
Na+ - Hyponatremia due to excess ADH from hypothyroidism
Muscle enzymes, ALT & CK are all raised
Prolactin - Hyperprolactinaemia
How will TFT’s Appear for each class of Hypothyridism?
Primary - Low fT4 but high TSH
Secondary - Low fT4 & low or normal TSH
Subclinical - Normal fT4 & High TSH
What do we use to manage hypothyroidism?
Levothyroxine (T4) tablets
Explain the dosing of Levothyroxine?
Start at 50mcg/day
Titrate up to 100mcg/day after 2 weeks
Keep increasing until their TSH (primary disease) or fT4 (Secondary Disease) is normal.
What special cases affect how you use Levothyroxine?
- IHD needs to be started lower and titrated slowly as it can trigger Angina
- Pregnant women need more T4
- Myxedema Coma needs IV T3
- Post-partum Thyroiditis needs to have the meds removed for 6 weeks and TFTs measured to see when it abates
Should we treat subclinical hypothyroidism?
Only if:
- TSH >10
- > 5 + Antibodies
- TSH elevated + symptoms (temporary trial therapy for symptom improvement)
- Pregnant or planning pregnancy
What are the risks of levothyroxine?
- Thyrotoxicosis
- AF
- Osteopenia
How does Goitre occur in hypothyroidism?
No fT4
No -ve feedback
Excess TSH
Hyperstimulation -> Hyperplasia of Thyroid gland
What are the causes for PRimary hyperthyroidism?
Graves Disease - 70%
Toxic Multinodular Goitre - 20%
Thyroid Adenoma
Subacute Thyroiditis
What is Grave’s Disease?
Autoimmune condition in which TSH receptor antibodies continuously stimulate the thyroid causing PRimary hyperthyroidism
What is Toxic Multinodular goitre?
Multinodular Goitre producing excess thyroid hormones
Whats the main cause of secondary hyperthyroidism?
Pituitary Adenoma producing TSH
What is Thyrotoxicosis without hyperthyroidism?
Where you get excess thyroid hormone without hyperthyroidism.
Due to exogenous thyroxine or destructive thyroiditis causing stores of thyroid hormones to be released
What causes destructive thyroiditis?
Post-partum
Amiodarone induced
Most common causes
