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.

[Click here to toggle visibility of the answers]

College Answer

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.

Discussion

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:

  • cardiovascular collapse
  • hypothermia
  • decreased level of consciousness

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.

References

References

Summers, V. K. "Myxoedema coma." British medical journal 2.4832 (1953): 366.

 

Wartofsky, Leonard. "Myxedema coma." Endocrinology and metabolism clinics of North America 35.4 (2006): 687-698.

 

Mathew, Vivek, et al. "Myxedema coma: a new look into an old crisis." Journal of thyroid research 2011 (2011).

 

Lezama, Maybelline V., Nnenna E. Oluigbo, and Jason R. Ouellette. "Myxedema Coma and Thyroid Storm: Diagnosis and Management." Internal Medicine 14.Part 2 (2011): 1.

 

Chu, Michael, and Terry F. Seltzer. "Myxedema coma induced by ingestion of raw bok choy." New England Journal of Medicine 362.20 (2010): 1945-1946.

 

Wall, Cristen Rhodes. "Myxedema coma: diagnosis and treatment." American family physician 62.11 (2000).

 

Bondugulapati, Laxmi, Mohamed Adlan, and Lakdasa Premawardhana. "Thyroid Emergencies." Sri Lanka Journal of Critical Care 2.1 (2011): 1-12.