THYROTOXICOSIS – hypermetabolic clinical syndrome
Thyrotoxicosis is the hypermetabolic clinical syndrome resulting from elevation of the thyroid hormone levels either specifically free thyroxin (T4), triiodothyronine (T3) or both. Vast majority of thyrotoxicosis is caused by hyperthyroidism. Some of the thyrotoxicosis cases are caused by inflammation of the thyroid gland, which causes release of stored thyroid hormone. Other cases of thyrotoxicosis may be caused by ingestion of exogenous thyroid hormone. It is very important to differentiate the causes of the thyrotoxicosis because the management is different.
Clinical presentation (symptoms):
· Weight loss despite of increase appetite
· Heat intolerance (preference to cold weather)
· Sweating (can be seen over palmar area)
· Diarrhea
· Tremor – fine tremor on stretching the arms
· Easily to be irritable
· Frenetic activity
· Emotional lability
· Psychosis
· Itch
· Oligomenorrhoea in female – this may later lead to infertility
Clinical Signs:
· Tachycardia (increase pulse rate)
· May have irregular irregular pulse rate (atrial fibrillation)
· Warm peripheries
· Fine tremor
· Palmar erythema (redness of palm of the hand)
· Lid lag (there is one test to examine this, draw the hand from up down, the eyelid lags behind eye’s descent as patient watches the finger descend slowly)
· Lid retraction (the patient will have ‘stare’ appearance where there is exposure of sclera above iris)
· Thinning of hair
· May be present of goiter or thyroid nodules or bruit (depends on the causes)
Associated skin changes:
· Pink and soft skin
· Hyperhydrosis (a condition for the person is sweating too much)
· Alopecia (hair falls)
· Pigmentation of the skin
· Onycholysis
· Clubbing
· Pretibial myxoedema (raised eryhthematous plaques on shins)
Investigations:
· TSH level (Thyroid Stimulating Hormone) – the level will be decrease, T4 and T3 counts will increase
· FBC (full blood count) – mild normocytic anemia may present with mild leucopenia (decrease of total white cell count)
· ESR – increase
· Calcium level – usually increase
· LFT (liver function test) – may increase
· Thyroid auto antibodies
· Isotope scan – indicated if the cause is unclear, this is needed to detect nodular disease or sub acute thyroiditis
· Eye examination for visual fields, vision acuity and eye movements – if patient has ophthalmopathy
Thyroid causes of thyrotoxicosis:
1. Graves’ disease – Consist of 80% – 90% of all hyperthyroidism cause
2. Toxic multinodular goiter
3. Toxic adenoma
4. Other causes apart of hyperthyroidism
- Sub acute (de Quervain’s) thyroiditis – self limiting viral infection with painful goiter
- Thyroxin intoxication causes increase T4, decrease T3 and decrease thyroglobulin
- Ectopic thyroid tissue – metastatic follicular thyroid cancer, choriocarcinoma or struma ovarii (ovarian teratoma containing thyroid tissue).
Treatment:
1) Beta blockers (e.g.: propanolol 40mg/6 hours) – to control symptoms of palpitations
2) Anti-thyroid medications - carbimazole and propylthiouracil,
3) Radioiodine – this treatment is very effective however many patients become hypothyroid post treatment. There is no noted evidence of increase risk for cancer, birth defect or infertility in women however it is contraindicated for pregnant and lactating mother.
4) Thyroidectomy – there is high risk of hypoparathyroidism and recurrent laryngeal nerve damage that may lead to hoarseness of voice.
5) Topical steroid – local application to improve pretibial myxoedema
6) Withhold thyroxin therapy if thyrotoxicosis is due to exogenous thyroid therapy
Complications:
· Heart failure due to thyrotoxic cardiomyopathy (risk is higher in elderly)
· Angina or chest pain
· Atrial fibrillation (irregularly irregular pulse) – seen in 10-25% of cases
· Osteoporosis
· Ophtalmopathy – thyroid eye disease
· Gynaecomastia (enlargement of breast in men)
· Thyroid storm
Other relevant topics:
· Thyrotoxicosis
Reference:
1. Oxford handbook of Clinical Medicine. 7th edition. Oxford University Press. 2008.
2. http://emedicine.medscape.com/article/383062
3. Oxford handbook of general practice. 2nd edition. Oxford press. 2005.
Tags: atrial fibrillation, hyperhydrosis, hyperthyroidism, lid lag, opthalmopathy, pretibial myxoedema, psychosis, thyroid storm, thyroiditis, thyrotoxicosis, tremor, weight loss
Technorati Tags: atrial fibrillation, hyperhydrosis, hyperthyroidism, lid lag, opthalmopathy, pretibial myxoedema, psychosis, thyroid storm, thyroiditis, thyrotoxicosis, tremor, weight loss
