Question 6.2

Angoff score

6.41

Highest mark

9.25

A 38-year-old patient is ventilated due to a severe Influenza A with superimposed bacterial pneumonia.
The patient has a BMI of 58 and no other comorbidities. These are the blood results on day 5.

Full blood count	Patient	Reference
Haemoglobin	67g/L*	120-160
Mean Cell Volume	104pg*	80-99
White Cell Count	10.2x 109/L	4-11
Platelet Count	242x 109/L	150-350

Coagulation	Patient	Reference
INR	1.2	0.9-1.3
APTT	40 sec*	27-38.5
Fibrinogen	6.2 g/L*	2-4

Biochemistry	Patient	Reference
Sodium	138mmo/L	135-145
Potassium	4.2mmol/L	3.5-5.2
Glucose	17.5mmol/L*	3.5-7.7
Vitamin B12	307pg/mL	80-675
Folate	23nmol/L*	>7
Creatine kinase	1058 U/L*	55-170

For each of the following four abnormalities:

Macrocytic anaemia
Hyperfibrinogenaemia
Hyperglycaemia
High creatine kinase (CK)

i. List TWO likely causes in this patient. (2 marks)

ii. List TWO further tests you might order to explain each abnormality and provide your rationale. (4 marks)

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College answer

Syllabus topic/section:

2.1.5 Respiratory Intensive Care: Pneumonia: L1

2.1.11 Haematological and Oncological Intensive Care: Anaemia: L1

Discussion:

Part b) was answered less well with many candidates providing less than the requested number of causes, tests or rationale. In addition, the answer required the candidate to consider the likely causes in the described patient. Candidates are reminded to read the question carefully.

Discussion

This was thrown into the haem pile, as there is little actual pneumonia in the SAQ, except for in the stem. The extremely high Angoff mark suggests that "the borderline candidate" should be very familiar with this topic. Given that the author has been a "borderline candidate" himself, this seems plausible, as the abnormalities listed here are ones which have appeared in the past papers multiple times, and these were the main mechanism of exam revision in the past, which suggests that people must have stopped doing them since the college has moved to generating novel content for each paper. This pseudorepeat SAQ should therefore remind people that there is still value in the process of doing past papers. Having said this, one needs to point out that high fibrinogen levels have not been seen before, and moreover the question is made more challenging not so much by the content but by the need to create sixteen answers (i.e.

Macrocytic anaemia is done to death in the exam, and could be caused by:
Hypothyroidism	TFTs
Multiple myeloma	Serum protein electrophoresis, light chains
Alcoholism	LFTs (these are day 5 bloods, so doing a blood alcohol level is not going to help unless the patient is somehow self-administering it while intubated)
Sodium valproate	Valproate level
Bone marrow recovery	Reticulocyte count
Leukaemia	Blast cytometry
Haemolysis	LDH, haptoglobin

Vitamin B12 deficiency and folate deficiency, being low hanging fruit, were taken off the list by the examiners by giving normal values for these variables.

For an abnormally elevated fibrinogen, there are numerous possible causes, but most of them do not attract any specific tests (obesity, menopause, smoking?) and so the only ones listed are those that leave a biochemical footprint:

Hyperfibrinogenaemia could be caused by:
Sepsis	Blood cultures
Non-infective inflammation	CRP ESR and procalcitonin
Pregnancy	β-HCG
Malignancy	Specific tumour markers (CA125, CA-19.9, CA15-3, α-foetoproetin, etc)

Similarly for hyperglycaemia:

Hyperglycaemia could be caused by:
Stress response	Inflammatory markers
Diabetes	HBA1C, C-peptide
Corticosteroid therapy opr Cushing syndrome	Cortisol level
Pancreatitis	Lipase, amylase

A raised CK could be caused by:
Myocardial infarction	Troponin
Rhabdomyolysis from immobility or compartment syndrome	Phosphate, urinary myoglobin
Antibiotics	Daptomycin trough level
Hyper or hypothyroidism	Lipase, amylase

References

Lowe, Gordon DO, Ann Rumley, and Ian J. Mackie. "Plasma fibrinogen." Annals of clinical biochemistry 41.6 (2004): 430-440.

Kamath, Sridhar, and G. Y. H. Lip. "Fibrinogen: biochemistry, epidemiology and determinants." Qjm 96.10 (2003): 711-729.

Falciglia, Mercedes. "Causes and consequences of hyperglycemia in critical illness." Current Opinion in Clinical Nutrition & Metabolic Care 10.4 (2007): 498-503.

Aslinia, Florence, Joseph J. Mazza, and Steven H. Yale. "Megaloblastic anemia and other causes of macrocytosis." Clinical medicine & research 4.3 (2006): 236-241.

Chavez, Luis O., et al. "Beyond muscle destruction: a systematic review of rhabdomyolysis for clinical practice." Critical care 20.1 (2016): 135.

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