Thyroid Disease Flashcards
What is the lifetime risk of thyroid disease in a woman?
20%
When is undiagnosed thyroid disease especially dangerous?
Pregnancy/peripartam
Cardiac disease
How often do ranges for thyroid function tests change during pregnancy?
Trimester to trimester
What blood test is a good screening test for hypothyroidism?
TSH
What blood tests do you do if you’re considering secondary hypothyroidism?
TSH and T4
What is sub-clinical hypothyroidism?
T4 normal, elevated TSH
What are the symptoms of hypothyroidism?
Malaise Tiredness Myalgia Depression Cold intolerance Constipation Weight gain
What are the signs of hypothyroidism?
Delayed tendon reflexes Bradycardia Myxoedema Voice change Myopathy Hypothermia Effusions
What are the most common causes of hypothyroidism?
Autoimmune
Iatrogenic
Drugs
What is thyroiditis?
Inflammation of thyroid gland
What is the natural history of thyroiditis?
Initially hyperthyroid phase because some follicles rupture and release thyroid hormone - 4-8 weeks Then have hypothyroid phase - 4-8 weeks Transient and self-limiting
How is hypothyroidism diagnosed?
Check TSH and free T4
Correlate with symptoms and clinical exam
Anti-thyroid Abs can sometimes be helpful
What is the treatment for hypothyroidism?
Thyroxine
- 1.3-1.6 mg/kg
After how long do you adjust thyroxine dose?
6-8 weeks
- No hurry except in pregnancy
What medications may decrease thyroxine absorption?
Iron tablets
Calcium tablets
Antacids
Cholestyramine
Is a nuclear scan important in hypothyroidism?
No
What are differential diagnoses for thyrotoxicosis?
Caffeine
Anxiety/panic disorder
Primary pulmonary/cardiac disorder
What are the symptoms of hyperthyroidism?
Heat intolerance Weight loss Increased appetite Increased sweating Tremulousness Anxiety Emotional lability Hair loss Increased frequency of bowel movements Menstrual irregularity
What are some of the causes of hyperthyroidism?
Graves' disease Toxic nodular goitre Iodine-induced - Radiographic - Naturopathic remedies - Amiodarone Exogenous Transient
What are the possible signs of hyperthyroidism?
Increased heart rate Irregularly irregular rhythm Tremor Skin, nail and hair changes Thyroid size, consistency, bruit - May have diffuse, soft goitre - May have bruit over thyroid Pemberton's sign
What eye signs may be present in Graves’ disease?
Redness and irritation
Staring appearance
Mild double vision on extreme lateral gaze
What are the investigations for hyperthyroidism?
TSH
Free T3 and T4
Nuclear scan if unsure of cause
Abs against TSH receptor if suspect Graves’ disease
What is the appearance of a nuclear scan in Graves’ disease?
Normal/increased uniform uptake
What is the appearance of a nuclear scan in thyroiditis?
Decreased/no uptake
- Due to inflammation
What is the appearance of a nuclear scan if one or more nodules are present?
Non-uniform uptake
Which age group is particularly at risk of developing atrial fibrillation as a result of hyperthyroidism?
Elderly
What are the treatment options for hyperthyroidism?
Anti-thyroid drugs - Carbimazole - Propylthiouracil Radioactive iodine Surgery only if other reasons - Adverse reactions to drugs - Cosmetic/patient preference - Risk of malignancy
What is the pattern of disease in Graves’ disease?
Remitting-relapse
What is the management of Graves’ disease?
Try anti-thyroid drugs, but they don’t often work
Need to remove thyroid, either via radiation/surgery
Are anti-thyroid drugs safe to use in pregnancy and lactation?
Yes, but try and avoid use
- Propylthiouracil safer in first trimester
What are the side effects of anti-thyroid drugs?
Commonly, rash
Very small risk of granulocytosis
How long do you treat Graves’ disease for with anti-thyroid drugs?
12-18 months
What medication can be used to help alleviate the symptoms of hyperthyroidism initially?
Beta-blockers
What are the features of radioactive iodine as a treatment for hyperthyroidism?
Very effective and permanent
Permanent hypothyroidism frequent outcome
Small risk of thyroid eye disease
Must not be pregnant
Must not have had ordinary iodine for months
What are the features of surgery for thyrotoxicosis?
Usually only considered if
- Large goitre with obstructive/cosmetic concerns
- Significant possibility of incidental thyroid malignancy
- Intolerant of anti-thyroid drugs and radioactive iodine therapy refused/contraindicated
What tests may be helpful in the confirmation of thyroiditis?
CRP
ESR
WCC
If antibody testing is negative in the instance of hyperthyroidism, what test can be done, and what can it indicate?
Measure thyroglobulin levels
Elevated in thyroiditis
If normal, may indicate exogenous cause
What is the management of sub-clinical hypothyroidism?
Observe/treat according to clinical circumstances
