Thyroid Flashcards
TFTs in hyperthyroidism
Low TSH
High T3 + T4
Pituitary adenoma (High TSH and T3 T4)
TFTs in Primary Hypothyroidism
High TSH
Low T3/T4
TFTs in Secondary Hypothyroidism
Low TSH
Low T3/T4
What antibodies are most relevant thyroid autoantibody in autoimmune thyroid disease - Graves, Hashimoto’s ?
Antithyroid Peroxidase (anti-TPO) Antibodies
What is the use of measuring Antithyroglobulin Antibodies?
Usually present in Grave’s Disease, Hashimoto’s Thyroiditis and thyroid cancer
Can be present in normal individuals
What are TSH Receptor Antibodies?
Autoantibodies that mimic TSH, bind to the TSH receptor
Cause of Grave’s
What can radioactive iodine tell you about thyroid patologies?
Diffuse high uptake is found in Grave’s Disease
Focal high uptake is found in toxic multinodular goitre and adenomas
Cold” areas (i.e. abnormally low uptake) can indicate thyroid cancer
What is pretibial myxoedema?
Discoloured, waxy, oedematous appearance to the skin over ant. aspect of the leg
Specific to Grave’s disease
Reaction to the TSH receptor antibodies
Causes of hyperthyroidism
Grave’s disease
Toxic multinodular goitre
Solitary toxic thyroid nodule
Thyroiditis (e.g. De Quervain’s, Hashimoto’s, postpartum and drug-induced thyroiditis)
What are the features of hyperthyroidism?
Anxiety and irritability Sweating and heat intolerance Tachycardia Weight loss Fatigue Frequent loose stools Sexual dysfunction
Unique features of Grave’s
Diffuse Goitre (without nodules)
Graves Eye Disease
Bilateral Exopthalmos
Pretibial Myxoedema
Unique features of Toxic Multinodular Goitre
Goitre with firm nodules
Most patients are aged over 50
Second most common cause of thyrotoxicosis (after Grave’s)
What is a solitary toxic nodule?
Single abnormal thyroid nodule is acting alone to release thyroid hormone
Usually benign adenomas
Treated with surgery
What is De Quervain’s thyroiditis?
Presentation of a viral infection with fever, neck pain and tenderness, dysphagia and features of hyperthyroidism
Hyperthyroid phase followed by hypothyroid phase as the TSH level falls due to negative feedback
How is De Quervain’s thyroiditis treated?
Self limiting
NSAIDS for pain
Beta blockers for symptom relief
What is thyroid storm?
AKA thyrotoxic crisis
More severe presentation of hyperthyroidism with pyrexia, tachycardia and delirium
Treatment for hyperthyroidism
Carbimazole Propylthiouracil Radioactive Iodine Beta blockers Surgery + levothyroxine
What drugs can cause hypothyroidsim?
Lithium
Amiaodarone (can also cause thyrotoxicosis)
What is secondary hypothyroidism?
Pituitary fails to produce enough TSH
Often associated with lack of ACTH
Causes of seconday hypothyroidism
Tumours
Infection
Vascular (e.g. Sheehan Syndrome)
Radiation
Features of hypothyroidism
Weight gain Constipation Course hair / hair loss Dry skin Fatigue Fluid retention Heavy / irregular periods
Which cells produce PTH?
Chief Cells produce PTH in response to hypoalcaemia
How does PTH raise blood calcium? (4)
Increasing osteoclast activity in bones (reabsorbing calcium from bones)
Increasing calcium absorption from the gut
Increasing calcium absorption from the kidneys
Increasing vitamin D activity
Symptoms of hypercalcaemia
kidney STONES
painful BONES
abdominal GROANS (constipation, nausea, vomiting)
Psychiatric MOANS (fatigue, depression, psychosis)
What is the cause and effect of primary hyperparathyroidism?
Caused by tumour of the parathyroid glands
Leads to hypercalcaemia
Treated surgically
What is the cause and effect of secondary hyperparathyroidism?
Caused by vitamin D insufficiency or chronic renal failure
Leads to:
low absorption of calcium from the intestines, kidneys and bones
Hypocalcaemia
Hyperplasia of parathyroid glands
Treated with viamin D or renal transplant
What is tertiary hyperparathyroidism?
Happens when secondary hyperparathyroidism continues long term and there is hyperplasia of the glands
The cause is treated and the high level of PTH leads to high absorption of calcium
Treated surgically