Question 12.1

A 75-year-old patient presented with bone pain. Their biochemical profile is shown below:lt.

Parameter

Patient Value

Adult Normal Range

Sodium

140 mmol/L

135-145

Potassium

5.1 mmol/L*

3.5-5.0

Chloride

108 mmol/L*

95-105

Bicarbonate

21.0 mmol/L*

22.0-26.0

Glucose

6.0 mmol/L

3.5-6.0

Urea

25.0 mmol/L*

3.0-8.0

Creatinine

250 μmol/L*

45-90

Magnesium

1.10 mmol/L*

0.75-0.95

Albumin

25 g/L*

35-50

Protein

95 g/L*

60-80

Total bilirubin

26 μmol/L*

< 26

Aspartate transferase

60 U/L*

< 35

Alanine transferase

60 U/L*

< 35

Alkaline phosphatase

250 U/L*

30-110

g-Glutamyl transferase

40 U/L*

< 40

Ionised calcium

1.50 mmol/L*

1.10-1.35

Calcium corrected

2.90 mmol/L*

2.12-2.62

Phosphate

1.8 mmol/L*             

0.8-1.5

Lactate Dehydrogenase                        

350 U/L*

50-150

Beta-2 microglobulin

6 mg/L*

< 1

12.1.1    List the most likely diagnosis.    (1 mark)
12.1.2    List two factors that may predispose to infection in this patient.    (2 marks)

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College Answer

Syllabus topic/section:
2.1.21 Applied Pharmacology in Intensive Care.
Aim:
To allow the candidate to demonstrate competency in data interpretation.
Discussion:
Candidates generally did extremely well in this repeat data question. Candidates are reminded that if the question asks you to list 6 causes there are only marks for 6 answers. If 8 are written the top 6 will be assessed and the bottom 2 causes will not be marked.

Discussion

This is a repeat of Question 25.1 from the second paper of 2020.

a)

The abnormalities are:

  • A slightly raised potassium
  • A slightly raised chloride
  • A very mild metabolic acidosis
  • Renal failure
  • A borderline bilirubin
  • A low albumin
  • A rather high total protein, with a conspicuously raised β2-microglobulin
  • A raised calcium and alk phos, suggesting some sort of increase in bone resorption
  • An elevated LDH, suggestive of some kind of increased cell turnover in a broader sense

So, this is multiple myeloma. 

b)

Factors which increase the susceptibility to infection in myeloma and plasmacytoma are:

  • Impaired humoral immunity because of ineffective antibody production
  • This also means diminished response to vaccinations
  • Decreased antigen recognition because β2-microglobulin inhibits in vitro generation of functional dendritic cells (Kalambokis et al, 2009)
  • Decreased cell-mediated immunity due to bone marrow inflitration
  • Decreased innate immunity due to neutropenia from bone marrow infiltration
  • The possible immunosuppressant effects of treatment (bortezomib and dexamethasone)
  • Increased susceptibility to urosepsis due to higher protein content of urine

References

Kalambokis, G. N., L. Christou, and E. V. Tsianos. "Multiple myeloma presenting with an acute bacterial infection." International journal of laboratory hematology 31.4 (2009): 375-383.