Hyperthyroidism

Description

Graves' hyperthyroidism

Toxic multinodular goiter

Single toxic nodules

Thyroiditis

Thyroid crisis

Referral

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ICD-10 Code: E05.0-5/E05.8-9

DESCRIPTION

• Most common cause of hyperthyroidism is Graves’ disease, which is an autoimmune condition resulting from the presence of thyroid stimulating autoantibodies. 
• Other common causes are toxic single or multinodular goitre and sub-acute thyroiditis. 
• Thyrotoxicosis in the setting of any other acute life-threatening condition such as cardiac failure etc. should be managed as thyroid crisis - See Thyroid Crisis.

Investigation

• TSH and free T4.
  If TSH suppressed and free T4 normal, request free T3.
  The usual biochemical abnormalities are: low TSH, elevated free T4/3
• TSH receptor antibodies should be measured in all patients.
• Once thyrotoxicosis is confirmed, if cause is uncertain request thyroid uptake scan. If uptake is:
  - Elevated or diffuse: Grave’s disease.
  - Markedly decreased: Thyroiditis.
  - Patchy uptake with areas of increased uptake: Toxic multinodular goitre.

REFERRAL

• Consultation with a specialist is recommended in all cases.
• For thyroid scan if necessary.
• Thyroid-associated ophthalmopathy.
• When radioactive iodine or surgery is contemplated.
• If patient is pregnant.

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GRAVES' HYPERTHYROIDISM 

ICD-10 Code: E05.0

MEDICINE TREATMENT

• Carbimazole, oral, 20–40 mg daily.
  - Titrate dose according to thyroid hormone levels (T4).
  - Duration of therapy: 12–18 months.
  - Durations of therapy longer than 12 months must be in consultation with a specialist.

ß–blockers

Used to counteract excessive sympathetic symptoms, e.g. palpitations.
Dose is titrated according to the heart rate.
Give for 2–6 weeks, together with carbimazole until T4 levels normalise.

• ß–blocker, e.g.:
  • Atenolol, oral, 50 mg daily.
    - Titrate according to symptom control up to 100 mg daily.

LoE:III⁴²

Radioactive iodine

• In the setting of Graves’ disease radioactive iodine may be administered for failed medical therapy and may be indicated for patients with coexistent heart disease. 
• Refer patient if radioactive treatment is contemplated.

Surgery

• Seldom indicated, but to consider in the following situations: large thyroid causing obstructive symptoms, failure of anti-thyroid medicine therapy, allergy to anti-thyroid therapy, 2nd trimester of pregnancy and not responding to or allergic to anti-thyroid medication.

Monitoring

• Patients with Graves’ disease who are treated with anti-thyroid drugs should be monitored every 6–8 weeks using a serum T4. TSH may remain suppressed for months. 
• Once in remission, patients may be monitored less frequently to determine signs and symptoms of recrudescence of thyrotoxicosis.
• Because there is a risk of neutropenia or agranulocytosis with carbimazole, therapy should be temporarily stopped and a white cell count (with differential) must be done in patients presenting with an infection or sore throat.
• Post-radio-active iodine TSH and free T4 should be checked at 6 weeks, 3, 6, 9 and 12 months and annually thereafter until either hypothyroidism occurs or patient remains euthyroid for ± 3–4 years.  
• Although uncommon, new onset hypothyroidism can occur years later.

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TOXIC MULTINODULAR GOITER 

ICD-10 Code: E05.0

MEDICINE TREATMENT

Radio-active iodine

• Radioactive iodine is the treatment of choice.  
• Medical therapy is indicated initially for patients with underlying heart disease to achieve euthyroidism before radio-active iodine.  
• Surgery is restricted to patients with obstructive symptoms.

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SINGLE TOXIC NODULES 

ICD-10 Code: E05.1

MEDICINE TREATMENT

Radioactive iodine

• Smaller nodules are best managed with radio-active iodine while larger nodules may require surgery.

ß–blockers

Used to counteract excessive sympathetic symptoms, e.g. palpitations.
Dose is titrated according to the heart rate.
Give for 2–4 weeks.

• ß–blocker, e.g.:
  • Atenolol, oral, 50 mg daily.
    - Titrate according to symptom control up to 100 mg daily.

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THYROIDITIS

ICD-10 Code: E06.0-5/E06.9

• Toxic phase lasts up to 3 months.

MEDICINE TREATMENT

ß–blockers

Used to counteract excessive sympathetic symptoms, e.g. palpitations.
Dose is titrated according to the heart rate.
Give for 2–4 weeks.

• ß–blocker, e.g.:
  • Atenolol, oral, 50 mg daily
    - Titrate according to symptom control up to 100 mg daily.

For painful subacute thyroiditis (De Quervain’s): E06.1

• NSAID, e.g.:
  • Ibuprofen, oral, 400 mg 8 hourly with meals. 

AND

• Corticosteroids (intermediate-acting) e.g.:
  • Prednisone, oral, 40 mg daily (Specialist consultation).

LoE:III⁴³

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THYROID CRISIS

ICD-10 Code: E05.5

MEDICINE TREATMENT

IV fluids as indicated.

• Carbimazole, oral, 40-60 mg 6 hourly until crisis is controlled. 

LoE:III⁴⁴

30 minutes after the first dose of carbimazole:

• Lugol's iodine, oral, 10 drops in milk, 8 hourly.

AND

• ß–blocker, e.g.:
  • Atenolol, oral 50 mg daily
    - Titrate according to symptom control up to 100 mg daily.

If life-threatening

ADD

• Hydrocortisone, IV, 100 mg 8 hourly.

Actively manage precipitating illness and infection. ICU admission is desirable.

REFERRAL

• All patients once stabilised.

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Standard Treatment Guidelines and Essential Medicines List for South Africa, Hospital Level, Adults 2024 Edition