A 27-year-old patient presents with the following laboratory results after a prolonged sub-acute illness.
|
Parameter |
Patient Value |
Adult Normal Range |
|
Sodium |
132 mmol/L* |
135 – 150 |
|
Potassium |
2.2 mmol/L* |
3.5 – 5.5 |
|
Chloride |
94 mmol/L* |
100 – 110 |
|
Bicarbonate |
28 mmol/L* |
22 – 27 |
|
Urea |
8.3 mmol/L* |
3.0 – 8.0 |
|
Creatinine |
236 μmol/L* |
70 – 120 |
|
Total Calcium |
5.04 mmol/L* |
2.15 – 2.60 |
|
Ionised Calcium |
2.6 mmol/L* |
1.1 – 1.3 |
|
Magnesium |
0.7 mmol/L |
0.7 – 1.1 |
|
Phosphate |
1.09 mmol/L |
0.70 – 1.40 |
|
Albumin |
37 g/L |
35 – 47 |
|
Total Bilirubin |
8 μmol/L |
4 – 20 |
|
g-Glutamyl transferase |
105 U/L* |
0 – 50 |
|
Alkaline phosphatase |
263 U/L* |
40 – 110 |
|
Alanine transferase |
76 U/L* |
< 40 |
|
Aspartate transferase |
48 U/L* |
< 40 |
a) List the ECG changes associated with the most striking biochemical abnormalities. (1 mark)
b) List three differential diagnoses. (1.5 marks)
c) List three specific management strategies. (1.5 marks)
Syllabus topic/section:
2.1.7 Renal Intensive Care / Acid-Base and Electrolyte Disorders. L1
Discussion:
This is a core knowledge question which was generally answered well. This is an SAQ with simple lists of hypo and hypercalcaemia issues to complete. Candidates are reminded to only list the number of things asked for. If more than a stipulated number of responses is given (for example part b) asks for three differentials) the examiner will only mark the top three. It is not the responsibility of the examiner to pick the most appropriate of the answers given. This is a requirement of the candidate.
Several candidates omitted part/all of the question. Consider time management strategies to optimise the opportunity to address every question with enough time. We recommend practicing timed answers and practicing answering more than one SAQ consecutively during your preparation.
This is a deliberately timed examination designed to test recall and prioritisation as these are transferrable skills to senior, independent Intensive Care clinical practice. Every question is important for overall success. Candidates who have allocated enough time to address every question of the written paper have a statistically significant higher chance of successful participation and are more likely to be able to demonstrate the standard required on the journey to becoming a transitional fellow of the CICM
The most "striking" abnormalities? Would those be the values which are the furthest from their normal values? In which case that would be the creatinine, which is about five times higher than what it should be, for a young person. But one must conceded that the intention of this stem is clearly to draw attention to the calcium. To be fair, it's more than just a bit high. The potassium is also far from normal. Moreover the creatinine would not cause ECG changes.
In short:
ECG changes of hypokalemia
Ventricular tachycardia: classically, torsades de pointes
b) Differentials:
c) Management of hypercalcemia:
Glover, P. "Hypokalaemia." Critical Care and Resuscitation 1999; 1: 239-251.
Gennari, F. John. "Hypokalemia." New England Journal of Medicine 339.7 (1998): 451-458.
Weiner, I. David, and Charles S. Wingo. "Hypokalemia--consequences, causes, and correction." Journal of the American Society of Nephrology 8.7 (1997): 1179-1188.
Shane, Elizabeth, and I. Dinaz. "Hypercalcemia: pathogenesis, clinical manifestations, differential diagnosis, and management." Primer on the Metabolic Bone Diseases and Disorders of Mineral Metabolism, Favus MJ (ed.). Philadelphia: Lippincott, Williams &Wilkins (1999): 183-87.
Edelson, Gary W., and Michael Kleerekoper. "Hypercalcemic crisis." The Medical Clinics of North America 79.1 (1995): 79-92.
Carrol, Mary F., and David S. Schade. "A practical approach to hypercalcemia." Am Fam Physician 67 (2003): 1959-1966.