Thyrotoxic crisis : Investigations & Management :

Investigations :

ECG will show Sinus Tachycardia but Atrial fibrillation or other arrhythmias may be present.

Thyroid function tests would show Hyperthyroidism.

Thyrotoxic crisis is mainly a clinical diagnosis.

There are no specific lab investigations to diagnose thyrotoxic crisis.

The levels of thyroid hormones maybe the same as in uncomplicated hyperthyroidism.

Treatment should be started immediately as soon as clinical  diagnosis of thyrotoxic crisis has been made.

And time should not be wasted in confirming the diagnosis by lab investigations.

Management:

Thyrotoxic crisis is a life threatening condition with mortality of upto 20 – 30 % reported.

Aside from basic resuscitation give specific treatment for thyrotoxic crisis on clinical suspicion.

Hyperthyroidism :

The patient in thyrotoxic crisis requires both of the following :

Propylthiouracil or carbimazole :

Propylthiouracil is the preferred drug as it both blocks the further synthesis of thyroid hormones and inhibits peripheral conversion of T4 to T3.

However it is often not immediately available on the wards whereas carbimazole usually is.

If propylthiouracil is available ,give a loading dose of 600 mg to 1 Gm orally or via nasogastric tube and then 200 mg every 6 hours.

If PTU is not available, carbimazole 20 mg shoul be given followed by 20 mg three times a day.

Lugol”s iodine : Saturated solution of potassium iodide :

5 drops every 5 hours beginning 4 hours after starting PTU / Propylthiouracil / carbimazole not before , as thyroid hormone stores may be increased) to inhibit further rrelease of thyroxine.

Supportive measures particular to Thyrotoxic crisis :

Hyperpyrexia:

Peripheral cooling measures and Paracetamol

Aspirin should not be used as it can displace thyroid hormones from its binding sites.

Tachycardia :

Give propranolol 1 mg iv repeated every 20 minutes as necessary upto total of 5 mg or give 40 – 80 mg PO four times a day.

Be cautious in case of patient having Cardiac failure.

Esmolol is a short acting beta blocker and can be used as an infusion for immediate management of sympathetic overactivity.

Atrial fibrillation :

Consider digitalization but note that higher doses of digoxin than usual may be needed due to relative resistance to the drug.

Steroids : hydrocortisone 200 mg iv then 100 mg every 6 hours or dexamethasone 2 mg po four times daily .

Treat possible precipitating causes :

Start broad spectrum antibiotics if there is any suggestion of infection.