Hyperthyroidism Flashcards
Background
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.
Causes of hyperthyroidism
G – Graves’ disease
I – Inflammation (thyroiditis)
S – Solitary toxic thyroid nodule
T – Toxic multinodular goitre
- 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) - Nodular Disease (Toxic Multinodular Goitre):
- More common elderly esp. women
Nodules form on thyroid gland - continuously produces excessive thyroid hormone. Happens slowly over time. - Toxic adenoma:
Excess secretion of thyroid hormone results from a benign monoclonal tumour that usually is >2.5 cm in diameter. - 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. - 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
Risk factors
- Smoking history
- History of autoimmune disease
- family history of thyroid disease
- Female
- Low iodine intake
Signs and Symptoms
- 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
Diagnosis
- 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
Treatment
NON DRUG:
- Radioactive iodine or surgery (specialists in graves or toxic nodular goitre might) - whilst waiting should be on anti-thyroid drugs.
B4 STARTING Antithryroid meds CHECK FBC, LFT
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 AEs, pregnant, trying within 6 months or Hx of pancreatitis, THEN use Propylthiouracil (1st trimester) (risky in pregnancy)
But stop propylthiouracil If agranulocytosis occurs. 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
Thyroid storm (thyrotoxic crisis)
Medical emergency
Refer urgently if pituitary or hypothalamic disorder is SUS and all with new onset hyperthyroidism
Malignancy refer to cancer.
Symptoms - Tachycardia, high temp, diarrhoea, V, Jauindice, and Fainting.
WHILST WAITING use ANTITHYROID
DRUGS: Carbimazole 1st alt Propylthiouracil.
Treatment:
-IV fluids
- Propranolol
- Hydrocortisone
- Oral iodine/Carbimazole/Proplythiouracil
Thyrotoxicosis without hyperthyroidism usually happens from thyroiditis or excess levothryoxine use
Treatment:
Anti-thyroid meds with Adjunct B-Blocker propranolol (most common), metoprolol, and nadolol.
Note: AVOID iodine long term.
Managing complications
Ophthalmopathy: lubricant eye drops or gel. Severe cases require oral prednisolone.
Localised severe myxoedema: topical steroids under occlusive dressings.
HYPOTHYROIDISM
Too much useage of carbimazole/Proplythiouracil can lead to hypo, which would need levo to treat.
- AVOID these drugs during pregnancy (cause foetal goitre [enlarged thyroid in foetus])
Hypothyroidism can occur with the block and replace regimen if too much block is done but AVOID regimen in pregnant women can use propyl at low doses but risky.
Key drug notes
AVOID radioactive iodoine in pregnancy
Carbimazole/Proplythiouracil
Both drugs cross placenta and at high doses cause foetal goitre or hypothyroidism.
Propylthiouracil used in 1st trimester
- Carbimazole causes congenital effects.
SWITCH to carbimazole in 2nd trimester carry on to 3rd.
- Hepatoxicity risk with Propylthiouracil (dark urine, jaundice, NV, fatigue, abdo pain)
Carbimazole
Safety info:
STOP in bone marrow suppression.
Report infection signs esp sore throat.
STOP ASAP lab shows neutropenia.
- PT to tell dr asap of sore throat, mouth ulcers, bruising, fever, malaise.
MHRA - AVOID in pregnancy 1st trimester - Congential defects.
- Acute pancreatitis
Propylthiouracil
Monitor for hepatoxicity. STOP if occurs.
Medical advise if anorexia NV, jaundice, Abdo pain, fatigue, Dark urine, pruritis.
