2007
Oliver Munroe is a 79-year-old man who is brought to the hospital emergency department by ambulance after being found collapsed at home by his daughter. He is semi-conscious, disoriented and breathing rapidly. He appears to have vomited blood (haematemesis). The ambulance officer finds a blood pressure of 60/40, pulse 120 and respiration rate, 28 breaths/min.
Question 7 Give two hypotheses to account for Mr Munroe’s collapse and rapid breathing. For each hypothesis outline a sequence of events that might have led to his collapse. (12 marks)
Question 8:Describe four key laboratory tests that would help you distinguish between your hypotheses. Explain how you would interpret possible results from these tests in relation to your hypotheses. (13 marks)His daughter reveals that Mr Munroe has a recent history of melaena (black tar-like stools). Laboratory tests on his plasma and on an arterial blood sample gave the following results:
Plasma |
|
|
Value |
Units |
Reference |
Na+ |
139 |
mmol/L |
135-145 |
K+ |
4.3 |
mmol/L |
3.2-43 |
Cl- |
99 |
mmol/L |
99-109 |
HCO3- |
6 |
mmol/L |
23-33 |
Urea |
24.0 |
mmol/L |
3-8 |
Creatinine |
240 |
mmol/L |
90-120 |
Glucose |
6.5 |
mmol/L |
3-7.8 |
Lactate |
28 |
mmol/L |
<2.0 |
Beta-hydroxybuterate |
<0.3 |
mmol/L |
<0.3 |
|
Blood |
|
|
|
|
|
Haemoglobin |
57 |
g/L |
130-175 |
PO2 |
90 |
mmHg |
80-100 |
PCO2 |
22 |
mmHg |
35-45 |
HCO3- |
7 |
mmHg |
24-32 |
pH |
7.13 |
|
7.35-7.45 |
Question 9:State what is now your preferred hypothesis to account for Mr Munroe’s collapse and rapid breathing. Provide an explanation for each of the laboratory findings, indicating how they relate to your hypothesis, where appropriate. (20 marks)
2010
John Davidson, a 57 year old man presents to his general practitioner with symptoms of progressive tiredness over 6 months, shortness of breath on exertion for two weeks with associated palpitations. He is a lawyer working 55 hours per week, eating take away food and not exercising to keep fit. His BMI is 30. He has no personal or familial cardiac history. He also gives a vague story of increased thirst and getting up at night to pass urine. On examination he is pale but not jaundiced. Pulse rate 90 beats per minute and respiratory rate 18 breaths per minute at rest, with no evidence of cardiac failure. He appears mildly dehydrated. Abdominal examination is unremarkable.
Question 10 Formulate two (2) different clinical hypotheses that could explain this man’s symptoms. For each hypothesis explain how the symptoms and examination findings contribute to this case scenario and the mechanisms underlying these conditions. (15 marks)
|
Reference Range |
Hb 90mg/L |
115-150 |
MCV 74 fL |
80-100 |
WCC 8x109/L |
4-10 |
Platelets 500x109/L |
150-450 |
|
|
Sodium 141 mmol/L |
137-145 |
Potassium 4.4 mmol/L |
3.2-4.4 |
Chloride 107 mmol/L |
100-109 |
Bicarbonate 26 mmol/L |
22-32 |
Glucose 16.4 mmol/L |
3.2-5.5 |
Creatinine 88 mcmol/L |
50-120 |
Question 11. How would John’s anaemia be broadly classified given only the above laboratory information? Give 3 separate causes of this class of anaemia. (4 marks)
Question 12. Briefly discuss the laboratory tests required to distinguish between these 3 causes of anaemia. (6 marks)
Question 13. Suggest the most likely explanation for John’s glucosuria. In your answer, include an indication of the likely underlying disorder, explaining your reasoning. (9 marks)