A 65 year old obese lady with known alcoholic cirrhosis and long term thyroxine supplementation was admitted to ICU with staphylococcal spinal osteomyelitis 6 weeks ago. Following discharge to the ward, she developed progressive abdominal distension, hypotension and oliguria. On examination she was confused, with a flapping tremor. Her pulse rate was 42/min, in sinus rhythm and her blood pressure was 80/40 mm Hg. Her temperature was 34.7˚C. Bowel sounds were absent. There was no abdominal tenderness
Investigations subsequent to her admission were as follows: Blood tests:
|
Normal values |
|||
|
Hb |
110 |
G/L |
110 - 150 |
|
WCC |
8.4 |
109/L |
5 - 11 |
|
Platelets |
173 |
109/L |
150 - 300 |
|
Na |
131 |
mmol/L |
135 - 145 |
|
K |
3.6 |
mmol/L |
3.5 - 5.0 |
|
Urea |
26 |
mmol/L |
4 - 6 |
|
Creatinine |
167 |
micromol/L |
60 - 120 |
|
Glucose |
2.2 |
mmol/L |
4 - 6 |
|
Cholesterol |
8.6 |
mmol/L |
4 - 6 |
|
AST |
40 |
U/L |
35 - 45 |
|
ALT |
51 |
U/L |
35 - 45 |
|
Ammonia |
41 |
micromol/L |
50 - 80 |
|
Calcium |
2.25 |
mmol/L |
2.2 - 2.6 |
CT brain scan: Normal
Echo: Moderate pericardial effusion
(a) In light of this information, what is the most likely diagnosis? Justify your response.
(b) List 2 precipitating factors.
a) The most likely diagnosis is Myxoedema coma /severe hypothyroid coma. The normal CT brain excludes a significant organic brain pathology, and normal ammonia + normal hepatic enzymes make hepatic encephalopathy less likely. The clinical picture in concert with the features of a low Na, low glucose, high cholesterol, a pericardial effusion and the history of thyroxine supplementation is highly suggestive of hypothyroidism. Marks were also allocated if a reasonable alternative diagnosis was given, provided that this was accompanied by a rational justification.
b) Many precipitating factors could be present, but consider: sepsis, drugs (eg. betablockers, amiodarone), stroke, and a patient non-compliant with therapy.
Sixteen out of twenty-six candidates passed this question.
The history is characteristic of myxoedema coma, which is discussed in greater detail elsewhere
In addition to the background of hypothyroidism, the patient has the trifecta of features:
The associated features of pericardial effusion and hyponatremia complete the classical picture.
The college have not given you the puffy face and non-pitting oedema, but they are hardly necessary.
Also, the history of cirrhosis is given, and the patient does have a "flap", but it is probably not a flap of hepatic encephalopathy, but of hypercapnea, which is associated with myxoedema coma. The ammonium level is 41, which (though not related to the severity of encephalopathy) is not sufficiently abnormal to cause concern.
As for the precipitating factors... Surely, the osteomyelitis itself might cause the myxoedematous decompensation, but the clever college examiners have probably thrown this in because they know that osteomyelitis of this sort tends to be treated with rifampicin, and rifampicin tends to increase the rate of hepatic clearance of thyroxine.
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