These are  the biochemical  results  taken  from a  50-year-old woman, missing from an alcohol rehabilitation  programme, who was found in her home by police three days since she was last seen.  Blood was drawn for investigation.

Na

126

mmol/l

138 - 145

K

3.5

mmol/l

3.6 - 5.2

Cr

0.25

mmol/l

0.04 - 0.1

Urea

7.0

mmol/l

3.1 - 7.5

Bilirubin (Total)

509

micromol/l

2 - 22

Protein (Total)

40

g/l

65 - 85

Albumin

20

g/l

38 - 48

ALP

153

IU/L

40 - 100

GGT

459

IU/L

0 - 50

ALT

336

IU/L

0 - 45

CK

400

IU/L

30 - 180

TroponinT

0.1

mcg/l

0.00 - 0.03

Glucose

3.2

mmol/l

3.5 - 5.6

Ammonia

342

micromol/l

0 - 50

Lactate

3.7

mmol/l

0.6 - 2.4

Based on these results, what is the most likely cause of her reduced conscious state?  Give reasons.   What  other  simple  blood  test  would  support  this  diagnosis?  What  is  the significance of the high plasma creatinine but normal urea concentrations?

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College Answer

Most likely cause is hepatic encephalopathy, but many other conditions would be excluded as part of her work up.  She has obvious liver dysfunction (GGT, ALT, bilirubin), supported by a low albumin and a very high ammonia level. Other results (eg. Na, Cr/urea, glucose) are not as extreme and less likely to contribute to her reduced conscious state.

An additional assessment of the synthetic function of the liver would support the diagnosis(eg. prothrombin time, which is a marker of severity and should be prolonged).

The high plasma creatinine probably reflects significant renal impairment (not rhabdomyolysis as CK only mildly elevated).   The urea value is probably a reflection of decreased production and a nutritional deficiency.  A normal value makes gastrointestinal bleeding and severe hypovolaemia unlikely as precipitants for the encephalopathy.

Discussion

This question closely resembles (but is not identical to) Question 29.2 from the second paper of 2011. The key difference is that in 2011, it was a 48 yr old male who escaped from the alcohol rehab camp. However, the bloods were identical.

In contrast to the 2011 question, this time the examiners are asking us for ONE diagnosis.

So, if the candidate were to put all their money on one pony, it would be hepatic encephalopathy. The ammonia, bilirubin, LFTs and background history all point to this. The one test which the college has not provided us with is the coags- coagulopathy would be informative as a part of the staging process for this condition, particularly the prothrombin time.

The significance of the creatitine and urea disparity is probably an issue of dehydration. The patient, haveing collapsed some time ago, has spent some hours/days slowly dehydrating. However, owing to the greatly diminished oral intake and muscle mass, the patient probably has a very slow rate of urea production. The absence of CK demonstrates the fact that rhabdomyolysis has no role to play in this process.