Limit testing for thyroid disease to appropriate patients, namely those with a significant pre-test probability of abnormal results, such as:
those with classic signs or symptoms of thyroid disease.
those whose symptoms or signs are not classic, but who are at a higher risk for disease (e.g., the elderly, postpartum women, those with a history of atrial fibrillation, those with other endocrine disorders).
In patients with established thyroid disease, do not check thyroid-stimulating hormone levels too often, but rather test at the appropriate times, such as:
after changing medical doses.
when following patients with mild disease before initiating treatment.
periodically in stable patients receiving treatment.
When examining the thyroid gland, use proper technique (i.e., from behind the patient, ask the patient to swallow), especially to find nodules (which may require further investigation).
Risk Factors for Thyroid Disease
Women >45yo
Postpartum
No clear impact (benefit or harm) for universal screening in pregnancy
Radiation
Drug-induced (lithium, amiodarone)
Lithium can cause goiter, hypothyroidism (more common), hyperthyroidism
Interferon alfa-2b may cause hypothyroidism or hyperthyroidism
Autoimmune disease (eg. DM1)
Strong family history of thyroid disease
Symptoms
Hypothyroidism
Mood: Depression
Memory
Motor: Fatigue/Lethargy
Mass: Weight gain
Metabolism: Cold intolerance
Menstrual irregularities
Constipation
Dry skin
Hyperthyroidism
Palpitations/ tachycardia/ atrial fibrillation
Widened pulse pressure
Nervousness and tremor
Heat intolerance
Weight loss
Muscular weakness
Usually goiter is present
Investigations
TSH
TSH high (>4-5mU/L) - Possible Primary Hypothyroidism
FT4 to determine degree of hypothyroidism
Anti-TPO Ab once
TSH low (<0.2mU/L) - Possible Primary Hyperthyroidism
Free T4 and T3 to determine degree of hyperthyroidism
If no obvious cause (eg. Graves - new ophthalmopathy, goiter)
Thyrotropin receptor antibodies (TRAb)
Radioactive iodine uptake (contraindicated in pregnant/breastfeeding)