Hyperthyroidism

Question 1

Background

Answer 1

Thyroid hormone function:
- For growth and development
- Regulates cellular metabolism

Hyperthyroidism = Excessive production and secretion of thyroid hormones (T3 AND T4) leading to thyrotoxicosis (excess of circulating thyroid hormone)

Types:
- Primary = Due to thyroid. Thyroid behaving abnormally and produces excess thyroid hormone.
- Secondary = Due to hypothalamus or pituitary. Pituitary produces too much TSH = Thyroid gland produces excessive hormones.
- Subclinical = T3 and T4 are normal and TSH levels are supressed. (absent/mild symptoms)
- Overt = TSH supressed but T3 and T4 elevated.

Question 2

Causes of hyperthyroidism

Answer 2

G – Graves’ disease
I – Inflammation (thyroiditis)
S – Solitary toxic thyroid nodule
T – Toxic multinodular goitre

1. Graves disease:
   - Autoimmune condition - body makes abnormal IgG immunoglobulin (thyroid receptor antibodies TRABs, anti-thyroid peroxidase anti-TPO and antithyroglobulin anti-TG antibodies). The antibodies stimulate the TSH receptors on the thyroid and stimulate thyroid hormone secretion. Characterised by OPHTALMOPATHY (wide open swollen eye look), dermopathy (painless swelling) pretibial area (shin)
2. Nodular Disease (Toxic Multinodular Goitre):
   - More common elderly esp. women
   Nodules form on thyroid gland - continuously produces excessive thyroid hormone. Happens slowly over time.
3. Toxic adenoma:
   Excess secretion of thyroid hormone results from a benign monoclonal tumour that usually is >2.5 cm in diameter.
4. Subacute thyroiditis:
   Inflammation in the thyroid gland which can be of viral or autoimmune origin. Sudden elevation of thyroid hormone occurs, leading to painful mildly enlarged thyroid glands.
5. Other:
   Struma ovari: Ectopic thyroid tissue with dermoid tumor or ovarian teratomas = excessive thyroid hormone = hyperthyroidism
   Iodide-induced thyrotoxicosis: Excessive iodine intake depletion of iodine hormones should return normal.
   Metastatic follicular thyroid carcinoma: Lesions keep ability to make thyroid hormones….

DRUGS THAT ELEVATE THYROID LEVELS:
* Supplements contains iodine.
* Amiodarone.
* Alemtuzumab (CD52 monoclonal antibody).
* Alpha-interferon.
* Highly Active Anti-Retroviral HIV Therapy

Question 3

Risk factors

Answer 3

• Smoking history
• History of autoimmune disease
• family history of thyroid disease
• Female
• Low iodine intake

Question 4

Signs and Symptoms

Answer 4

• Nervousness and anxiety.
• Increased sweating and heat intolerance.
• Tremor and muscle weakness.
• Weight loss despite increased appetite.
• Reduction in menstrual flow (oligomenorrhea).
• Tachycardia or atrial arrhythmia with elevated systolic BP.
• Warm, moist, smooth skin.
• Lid lag and stare.
• Disturbed sleep
• Diarrhoea

Question 5

Diagnosis

Answer 5

• Suspect If 1 or more symptoms can be seen.

If suspected:
- Ask on symptoms, pregnancy, medications, risk factors, Features of pituitary disease
- examine signs and symptoms, Thyroid enlargement
- Check serum TSH levels
If symptoms worsen recheck TFTs in 6 weeks again
- IF TSH below check T3 and T4.
- Can do blood test (find antibodies) or ultrasound to see thyroid gland

Question 6

Treatment

Answer 6

NON DRUG:
- Radioactive iodine or surgery (specialists in graves or toxic nodular goitre might) - whilst waiting should be on anti-thyroid drugs.

Thyroid storm = medical emergency
Refer urgently to endocrinologist if a pituitary or hypothalamic disorder is suspected and all with new onset hyperthyroidism
Malignancy refer to cancer.
WHILST WAITING ANTITHYROID
DRUGS: Carbimazole 1st alt Propylthiouracil.
B4 STARTING CHECK FBC, LFT Applies for below too

Graves disease:
1st line - Radioactive iodine
BUT if remission can be achieved with drugs/unsuitable
ALT Carbimazole
(12-18 month course- block and replace regimen with Levothyroxine) OR titration regimen,
ALT if SIDE EFFECTS, pregnant, trying to be within 6 months or history of pancreatitis THEN Propylthiouracil
- agranulocytosis STOP TREATMENT, DONT RESTART

Toxic nodular goitre:
Multiple nodule:
1st line - Radioactive iodine
ALT total thyroidectomy or life-long antithyroid drugs
Single nodule:
1st line - Radioactive iodine or surgery (hemithyroidectomy)
ALT life-long antithyroid drugs

Life long drugs same as Graves pathway for them.

Subclinical hyperthyroidism:
2 TSH reading <0.1mIU/litre at least 3 months apart = REFER specialist

Pregnancy and hyperthyroidism:
Refer to endocrinologist

Thyrotoxicosis without hyperthyroidism usually happens from thyroiditis or excess levothryoxine use treatment:
Anti-thyroid meds with Adjunct Beta blocker - propranolol (most common), metoprolol, and nadolol.

Question 7

Managing complications

Answer 7

Ophthalmopathy: lubricant eye drops or gel, severe cases require oral prednisolone.

Localised severe myxoedema: topical steroids under occlusive dressings.