Flashcards in Thyroid Disorders Deck (38):
`How does hypothyroidism present?
- Weight Gain
- Cold intolerance
- Brittle nails, thin/dry skin & hair
- Hyporeflexia, slow speech
- Lethargy & low mood
- Heavy periods
Severe cases can cause puffy face, large tongue, hoarseness and coma
How does hyperthyroidism present?
- Weight loss
- Heat intolerance
- Muscle weakness
- Frequent bowel movements
- Light periods
- Sweaty palms
- Thyroid eye symptoms (bulging)
How does gender affect thyroid disease?
Both hyper and hypothyroidism are much more common in women
What are the types of Hypothyroidism?
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
- Chronic Iodine Deficiency
- Post-subacute thyroiditis
What can cause secondary or tertiary hypothyroidism?
- Pituitary tumours
- 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?
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
- Serum Na+
- Muscle enzymes, ALT & CK
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?
- TSH >10
- >5 + Antibodies
- TSH elevated + symptoms (temporary trial therapy for symptom improvement)
- Pregnant or planning pregnancy
What are the risks of levothyroxine?
How does Goitre occur in hypothyroidism?
No -ve feedback
Hyperstimulation -> Hyperplasia of Thyroid gland
What are the causes for PRimary hyperthyroidism?
Graves Disease - 70%
Toxic Multinodular Goitre - 20%
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?
Most common causes
How do you diagnose Hyperthyroidism?
Based on the presentation and TFTs
Can do TSH receptor antibody test for Grave's Specifically
Describe how hyperthyroidism TFTs appear?
Primary - High fT4 & low TSH
Secondary - High fT4 & High TSH
Subclinical - Normal fT4 & low TSH
How is Hyperthyroidism treated?
1st) Anti-thyroid Drugs (ATDs)
Resection of thyroid or pituitary adenoma
How are anti-thyroid drugs used?
Carbimazole or Propylthiourcil
A titration regimen for 12-18 months then move on to radioiodine if uncured
How is Radioiodine used?
USed after ATDs fail
High dose ablative regimen cures 90% of patients but leaves 70% hypothyroid
When would we treat Subclinical hyperthyroidism?
- Persistant subclinical hyperthyroidism
- High cardiac risk patient
Risks of Hyperthyroidism treatments?
ATDs can cause a rash and agranulocytosis which is a rare and potentially fatal complication
Radioiodine makes ~70% of patients hypothyroid and can cause eye disease
What are the types of hyperparathyroidism?
Primary - sporadic or familial (MEN-1)
Secondary - Physiological response to low Ca2+ resorption due to kidney failure
Almost all primarys are due to adenomas, some hyperplasia and rarely carcinoma
How would you investigate a goitre?
- Isotope scabn
- CXR for retrosternal extension
IF you suspect cancer a serum calcitonin to rule out MEdullary Thyroid Cancer
What are the main types of thyroid cancer?
Vast bulk are differentiated Thyroid Carcinomas, either papillary or follicular.
Also Anaplastic, Lymphoma and medullary thyroid cancer.
How do Differentiated Thyroid Carcinomas spread?
Papillary carcinomas spread to local lymph nodes
Follicular Carcinomas metastasise to lung/blood/bone
What is medullary thyroid cancer?
Cancer of C cells in the thyroid gland
Associated with MEN 2
Treatments for Thyroid cancers?
High Dose radioiodine
Long-Term levothyroxine to suppress the tumour
Lymphoma - External RT/chemo
Anaplastic - Can be delayed with external RT
Thyroidectomy - Only treatment that works on medullary thyroid cancer