Question 30.1

You are asked to review an 80-year-old female in the Emergency Department who has
presented with a depressed conscious state. She has ischaemic heart disease and
paroxysmal atrial fibrillation. Her medication includes aspirin, metoprolol, and
amiodarone.
On examination she has a temperature of 34.5°C, she is drowsy with a GCS of 10, a
pulse of 50 beats/min and a blood pressure 90/40 mmHg. CT brain scan shows age
related atrophy. The blood results are as follows:

Parameter	Patient Value	Normal Adult Range
Sodium	120 mmol/L*	137 – 145
Potassium	4.0 mmol/L	3.5 – 5.0
Urea	6.0 mmol/L	2.5 – 7.5
Creatinine	90 micromol/L	50 – 100
Measured Osmolality	255 mmol/kg*	280 – 300
Glucose	3.0 mmol/L*	3.5 – 6.0
CK	1000 U/L*	20 – 200
Cholesterol	7.2 mmol/L	3.0 – 5.5

a) Give the likely diagnosis and the underlying cause to account for all these blood results.

b) List four measures essential for the specific management of this patient.

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College Answer

a)
Hypothyroidism secondary to amiodarone toxicity.

b)
 Commence thyroxine, probably low dose (50 – 100ug/day and slowly increase) or consider T3 orally or intravenously (give cautiously).
 Commence on glucocorticoids (Hydrocortisone 50 mg 6 hourly).
 Correct the hypoglycaemia with intravenous glucose.
 Correct the hyponatraemia very slowly with hypertonic saline to sodium 130 mmol/L (no more than 2 mmol/L per hour).

Discussion

The generic approach to myxoedema coma is offered here. Clearly, that is what is happening here: the patient is bradycardic, hypotensive and hypothermic, with hyponatremia, a raised CK and high cholesterol.

Management of this condition consists of the following steps:

Replace thyroid hormone - preferably IV
- loading dose is 300-400μcg
- a rising body temperature and normalising cardiovascular parameters alert you to the success of your management strategy
Replace corticosteroids - there is usually a concomitant adrenal insufficiency. One would use a "stress dose".
Correct the sodium: this is usually a hypervolemic hyponatremia which resembles that of CCF (in fact, it is because of exactly the same mechanism: poor cardiovascular performance leads to ADH and aldosterone driven retention of water and sodium, with a resulting hypervolemic hyponatremia. Because the patient is usually obtunded, one is obliged to correct a particularly low sodium with hypertonic saline, being careful not to demyelinate the CNS.
Good solid supportive management:
- Establish an airway if this is needed
- Maintain normoxia and normocapnea with the ventilator
- Maintain normotension to support organ system perfusion, with a catecholamine infusion
- Correct the Na⁺ deficit - consider using water restriction alone.
- Correct hypoglycaemia
- Correct hypothermia with warming blanket

For interest and reference, the generic manifestations of myxoedema coma are tabulated below:

Clinical Manifestations of Myxoedema Coma
Cardinal features Cardiovascular collapse, shock Hypothermia Decreased level of consciousness Associated examination findings A "puffy" face Macroglossia Periorbital oedema Coarse, sparse hair Non-pitting oedema Goitre	Biochemistry Hypothyroidism Hypercapnea Hypoxia Hyponatremia Hyposmolarity Elevated protein levels on LP High serum cholesterol Other findings Decreased QRS voltages Prolonged QT Bradycardia Pericardial effusion

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Question 30.1

College Answer

Discussion

Cardinal features

Associated examination findings

Biochemistry

Other findings