Question 23.3

The following blood tests are from an otherwise well 53-year-old patient, admitted to a general medical ward five days previously for intravenous antibiotic therapy for lower limb cellulitis. Admission blood tests were all normal. Over the last 24 hours the patient has become progressively oliguric but remains otherwise stable with normal vital signs.

The results of the full blood count and urea and electrolytes are as follows:

Parameter

Patient Value   

Normal Adult Range

Haemoglobin

132 g/L

130-175

White Cell Count

9.8 x 109/L

4.0-11.0

Platelets

321 x 109/L

150-450

Neutrophils

10.4 x 109/L*

1.8-7.5

Lymphocytes

2.06 x 109/L

1.50-4.00

Monocytes

0.3 x 109/L

0.2-0.8

Eosinophils

4.3 x 109/L*

0.0-0.4

Haematocrit

0.35*

0.40-0.52

Mean Cell Volume

92 fL

82-98

Mean Cell Haemoglobin

29.9 pg/cell

27.0-34.0

Mean Cell Haemoglobin Concentration             

326 g/L

310-360

Parameter

Patient Value

Normal Adult Range    

Sodium

140 mmol/L

135-145

Potassium

3.8 mmol/L

3.2-4.5

Chloride

106 mmol/L

100-110

Bicarbonate

22 mmol/L

22-27

Urea

28.0 mmol/L*

3.0-8.0

Creatinine

310 µmol/L*

45-90

Total Calcium

2.17 mmol/L

2.15-2.60

Phosphate

1.6 mmol/L*

0.7-1.4

Albumin

31 g/L*

33-47

Total Bilirubin

20 mmol/L

4-20

Conjugated Bilirubin

4 mmol/L

1-4

g-Glutamyl transferase

22 U/L

0-50

Alkaline phosphatase

60 U/L

40-110

Lactate dehydrogenase

213 U/L

110-250

Aspartate transaminase

34 U/L

< 40

Alanine aminotransferase

25 U/L

< 40

23.3.1 List the most likely cause of the oliguria.    (2 marks)

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College Answer

Syllabus topic/section:
2.1.14 Environmental Injuries and Toxicology in ICU – L1.
2.1.21 Applied Pharmacology in Intensive Care.
Aim:
To explore the understanding of data interpretation, toxidromes and management of dysnatraemias.
Discussion:
Overall, this question scored highly but the answers were not as well structured as the other data question 19. Some candidates missed parts of the question, which was really the only way to 'fail' this repeat data interpretation. The management of hyponatraemia was frequently muddled by candidates with many stressing that the correction must be slow but then giving both a fluid restriction and iv hypertonic saline or normal saline. These candidates appeared to have remembered parts of the management but not fully applied it correctly.

Discussion

Apart from subtle changes in grammar and a gender reassignment, this SAQ is an exact copy of Question 13.3 from the second paper of 2016, and so is the discussion section below:

The eosinophils. They are high.

Everything else is normal.

It could be nothing else. The cellulitis, presumably it got flucloxacillin - and then the cillin caused an interstitial nephritis, as they tend to do.

The college model answer from that year was even shorter:

Allergic / Acute Interstitial nephritis secondary to antibiotic use.      

References

Perazella, Mark A., and Glen S. Markowitz. "Drug-induced acute interstitial nephritis." Nature Reviews Nephrology 6.8 (2010): 461-470.