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.
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:
Cardinal featuresCardiovascular collapse, shock Hypothermia Decreased level of consciousness Associated examination findingsA "puffy" face Macroglossia Periorbital oedema Coarse, sparse hair Non-pitting oedema Goitre |
Biochemistry
Other findingsDecreased QRS voltages Prolonged QT Bradycardia Pericardial effusion |