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  3. Hyperthyroidism

Hyperthyroidism

NICE CKS Hyperthyroidism. Last revised: Jan 2025. NICE guideline [NG145] Thyroid disease: assessment and management. Last updated: Oct 2023.

Background Information

2 commonly confusing terms:
  • Thyrotoxicosis: clinical manifestation of excess circulating thyroid hormones, irrespective of the cause (i.e. hyperthyroidism can cause thyrotoxicosis)
  • Hyperthyroidism: overproduction of thyroid hormone by the thyroid gland

There are 3 main types of hyperthyroidism:
 
Type Free T4 TSH
Primary overt hyperthyroidism ↑ ↓
Secondary overt hyperthyroidism ↑ ↑
Subclinical hyperthyroidism Normal ↓

Primary causes:
  • Graves' disease - most common
  • Toxic multinodular goitre - 2nd most common
  • Toxic adenoma
  • Excess iodine
  • Amiodarone-induced thyrotoxicosis
  • Struma ovarii (ectopic thyroid hormone secretion in an ovarian teratoma)
  • Causes of high hCG levels (can stimulate TSH receptors on the thyroid gland)
    • Gestational thyrotoxicosis
    • Hyperemesis gravidarum
    • hCG-secreting tumours (e.g. choriocarcinoma or hydatidiform mole)


Secondary causes:
  • TSH-secreting pituitary adenoma
  • Pituitary thyroid hormone resistance syndrome (rare)
  • Hypothalamic disease (excess TRH production) (extremely rare)

  • Excess levothyroxine intake
  • Acute phase of transient thyroiditis
    • De Quervain's (subacute) thyroiditis
    • Postpartum thyroiditis

Diagnosis Guidelines

NICE recommends testing for thyroid dysfunction in:
  • Clinically suspected cases
  • Type 1 diabetes or other autoimmune disease
  • New-onset atrial fibrillation

Choice of test:
  • Primary hyperthyroidism suspected → TSH alone, and only measure free T4 if TSH is abnormal
  • Secondary hyperthyroidism suspected → TSH and free T4 at the start
 

Type Free T4 TSH
Primary overt hyperthyroidism ↑ ↓
Secondary overt hyperthyroidism ↑ ↑
Subclinical hyperthyroidism Normal ↓
 

 
Standard additional tests:
  • Anti-TSH antibodies (to check for Graves' disease)
  • Anti-TPO antibodies
  • FBC and LFT
  • ESR and CRP (if thyroiditis is suspected)
 

Imaging:
  • Consider technetium scanning of thyroid gland if antibodies are -ve
  • If there is palpable thyroid enlargement or focal nodularity → ultrasound neck

Summary Table

Condition Antibody serology Ultrasound findings Technetium / radioiodine uptake scan
Graves’ disease
  • Anti-TSH receptor antibodies +ve in >90%
  • Anti-TPO can be +ve
  • Diffuse enlargement
  • ↑ Vascularity 
  • ↑ Doppler
  • Diffuse ↑ uptake
Toxic multinodular goitre
  • -ve
  • Multiple nodules of varying size
  • Heterogeneous echotexture
  • Multifocal (patchy) ↑ uptake
Toxic adenoma
  • -ve
  • Solitary, well-defined nodule
  • Focal ↑ uptake (hot nodule)
  • ↓ Uptake of remaining areas
Hashimoto’s thyroiditis
  • Anti-TPO +ve in >90%
  • Diffuse enlargement
  • Heterogeneous hypoechoic echotexture
  • Diffuse ↓ uptake
Subacute (De Quervain’s) thyroiditis
  • -ve
  • Diffuse enlargement
  • Hypoechoic areas
  • ↓ Vascularity
  • Diffuse ↓ uptake
Thyroid cancer
  • -ve
  • Solid hypoechoic nodule +/- microcalcifications
  • Focal ↓ uptake
 

Management Guidelines

This section refers mainly to transient thyroiditis like De Quervain's thyroiditis and postpartum thyroiditis.

Symptomatic treatment with beta blockers (propranolol / metoprolol / nadolol) to manage symptoms is usually sufficient
  • Further treatment such as anti-thyroid drugs, radioactive iodine is generally not needed

Start symptomatic treatment (beta blocker - propranolol / metoprolol / nadolol) +/- anti-thyroid drugs while awaiting specialist assessment and further treatment

Offer a beta blocker (propranolol / metoprolol / nadolol) for symptomatic control

Definitive management depends on the underlying cause.
 

There is no clean-cut algorithm, instead the choice is guided by indications and contraindications.
 
Treatment Indication Contraindication
Radioactive iodine 1st line in most patients, unless contraindicated
  • Pregnancy and breastfeeding
  • Planning to conceive within the 4-6 months (both male and female)
  • Active thyroid eye disease
Anti-thyroid drug
  • 1st line: carbimazole
  • 2nd line: propylthiouracil
 1st line in:
  •  Mild uncomplicated disease (either anti-thyroid drug or radioactive iodine is suitable), or
  • Children and young people
  • Radioactive iodine contraindicated
 Carbimazole contraindications:
  • Women of childbearing potential (unless on effective contraception)
  • Severe blood disorders
  • Severe hepatic impairment
  • History of pancreatitis (not exactly a contraindication but NICE recommends considering prophylthiouracil instead)

Propylthiouracil contraindications:
  • Severe hepatic impairment
Total thyroidectomy 1st line in:
  • Thyroid malignancy suspected
  • Anti-thyroid drugs and radioactive iodine are ​​​​​​contraindicated
  

 

Important safety information regarding carbimazole:

  • Risk of agranulocytosis (check baseline FBC, but no need for monitoring as the risk is sudden and unpredictable)
  • Risk of congenital malformations (thus avoid in pregnancy and women of childbearing potential)
  • Risk of acute pancreatitis (rare but serious) (if acute pancreatitis develops, stop carbimazole immediately and permanently)

  • 1st line: radioactive iodine unless contraindicated

  • 2nd line: total thyroidectomy or anti-thyroid drug (1st line: carbimazole, 2nd line: propylthiouracil)
    • NB if malignancy is suspected, thyroidectomy is 1st line


Radioactive iodine contraindications:
  • Pregnancy and breastfeeding​​​​​​​
  • Planning to conceive within the 4-6 months (both male and female)
  • Active thyroid eye disease

TSH +/- free T4 and free T3 should be monitored.

After total thyroidectomy:

  • Offer levothyroxine replacement routinely

After radioactive iodine:
  • Offer levothyroxine replacement only if hypothyroidism develops

Consider seeking specialist advice on treating subclinical hyperthyroidism if:
  • TSH <0.1 on 2 separate occasions, 3 months apart, or
  • Symptomatic, or
  • Evidence of thyroid disease (e.g. goitre, +ve thyroid antibodies)

If treatment is not indicated:
  • Monitor TSH +/- free T4 and T3 regularly

See this article.

References

Author: Adams Lau
Reviewer:
Last edited: 15/08/25