Management of Hypothyroidism Flashcards
What dose of levothyroxine should fit and healthy patients be started on?
50-100mcg OD.
What dose of levothyroxine should be started in elderly patients or with IHD?
The BNF recommends that for patients with cardiac disease, severe hypothyroidism or patients over 50 years the initial starting dose should be 25mcg od with dose slowly titrated.
When should TSH levels be checked after starting or changing the dose of thyroxine?
If it is within range at recheck, when should you follow up?
Recheck: 8-12 weeks
Follow up: Annually.
What is the TSH range goal?
As the majority of unaffected people have a TSH value 0.5-2.5 mU/l it is now thought preferable to aim for a TSH in this range
What are some common symptoms of hypothyroidism?
Hair thinning, fatigue, weight gain, fertility issues.
What is the most common cause of hypothyroidism worldwide?
Iodine deficiency
What is the most common cause of hypothyroidism in the west?
Autoimmune thyroiditis.
If someone has autoimmune thyroiditis, What other autoimmune conditions should you consider?
T1DM, Addison’s Disease and pernicious anaemia.
What patients should you screen annually for hypothyroidism?
- Down’s/Turner Syndrome
- Patients taking lithium, amiodarone, thalidomide, interferons, sunitinib and rifampicin.
- Patients who have had radioiodine treatment or neck radiotherapy.
- Patients who have had a subtotal thyroidectomy.
- Patients with Addison’s disease or T1DM.
How should hypothyroidism be monitored?
- Measure TSH 8-12 weeks after starting a dose and changing a dose.
- Once stable then check annually.
- Low TSH in >60 years is associated with OP and AF so reduce levothyroxine if >60 years if TSH is between 0.1 to 0.4mU/L.
- Aim for TSH within the lower half of the reference range (0.4 to 2.5mU/L)
Who should be referred in the case of hypothyroidism?
- Less than 16 years.
- Subacute thyroiditis (viral infection)
- Pituitary disease. (secondary hypothyroidism)
- Pregnancy
- Presistent raised TSH or symptoms worsening.
What is the treatment pathway for hypothyroidism?
- Treat symptoms
- Keep TSH within the lower half of the reference range (0.4-2.5 mU/L)
- If >60yrs or IHD, give 25-50μg daily and titrate up every 3 to 6 weeks as tolerated.
- Subclinical Hypothyroidism give 75μg.
- EVERYBODY ELSE - 100μg for women and 125μg for men. Take at night.
- Check cholesterol and diabetes.
How should subacute hypothyroidism be investigated?
1/ Is the patient symptomatic?
- Yes –> Give a 3-6 month trial of thyroxine. If symptoms resolve then treat with lifelong thyroxine. If symptoms do not resolve do a thyroid peroxidase antibody and reconsider the diagnosis.
-
No –> Check thyroid peroxidase antibody.
- If positive then recheck thyroid annually.
- If negative then recheck thyroid 3 yearly.
How is hypothyroidism managed in pregnancy?
- Refer women with overt and subclinical hypothyroidism for shared obstetric care.
- Aim for TSH 0.4–2.0 mu/l.
- Increase usual levothyroxine dose by 30% once pregnancy (~25-50mcg) is confirmed.
- Monitor TSH at least once each trimester. (Every 4 weeks in the first trimester).
- After delivery reduce T4 to pre-pregnancy levels & recheck in 6-8 weeks.
- If hypothyroidism is diagnosed during pregnancy, specialist assessment is advised to aim to correct TSH as quickly as possible.
What are some side effects of levothyroxine therapy?
- Hyperthyroidism: due to over treatment
- Reduced bone mineral density
- Worsening of angina
- Atrial fibrillation
