A 68-year-old female with type 2 diabetes mellitus and hypertension has been unwell for a week with a history of abdominal pain, vomiting and loss of appetite. She was brought to the Emergency Department where she is found to be hypothermic, hypotensive and delirious.
Her blood test results are shown below:
Parameter |
Patient Value |
Adult Normal Range |
Fi02 |
0.6 |
|
pH |
7.07* |
7.35 - 7.45 |
P02 |
125 mmHg (16.67 kPa) |
|
PC02 |
18.0 mmHg (2.53 |
35 . 0 —45.0 (4.60 — 6.00) |
Sp02 |
||
Bicarbonate |
5.0 mmol/L* |
22.0 - 26.0 |
Base Excess |
-23.0 mmol/L* |
_2,0 _ +2.0 |
Lactate |
11.5 mmol/L* |
0.5-1 6 |
Sodium |
141 mmol/L |
135 - 145 |
Potassium |
5.4 mmol/L* |
3.5 - 5.0 |
Chloride |
93 mmol/L* |
95- 105 |
Glucose |
9.2 mmol/L* |
3.5 - 6.0 |
Urea |
29.0 mmol/L* |
3.0 - 8.0 |
Creatinine |
372 umol/L* |
45 — 90 |
Ionised calcium |
1.26 mmol/L |
1.10 - 1.35 |
Calcium corrected |
2.41 mmol/L |
2.12 - 2.62 |
Phosphate |
3.17 mmol/L* |
0.80 - 1.50 |
Creatinine Kinase |
99 u/L |
55 - 170 |
Haemoglobin |
77 g/L* |
120 - 160 |
White Cell Count |
16.4 x 109/L* |
4.0 - 11.0 |
Platelet count |
296 x 109/L |
150 - 350 |
a) Describe the abnormalities in her blood test results and give a possible cause for each.
(30% marks)
b) List six other investigations you would order. (30% marks)
a)
1. Severe HAGMA Anion gap 43 – sepsis, shock from any cause 2. Lactic acidosis – ischaemic bowel, sepsis, metformin toxicity
3. Delta ratio 1.6, pure high anion gap acidosis as per a.
4. Hyperglycaemia, stress response, not high enough to be primary cause of metabolic abnormalities
5. Renal impairment – sepsis, shock, impaired perfusion
6. Hyperkalaemia and hyperphosphatemia likely secondary to renal impairment 7. Anaemia – sepsis
8. Leucocytosis – sepsis, stress response
9. Elevated A-a Gradient @ 292mmHg – aspiration, pneumonia
(Any plausible answer acceptable.)
b)
1. Serum Ketones
2. Measured osmolality
3. Lipase
4. Septic screen
5. CXR
6. ECG and troponin
7. Transthoracic echocardiogram
8. CT abdomen (or USS)
9. Renal USS
10. LFT’s
Examiner Comments:
Examiners noted a lack of detail in some answers with anion gap or Aa gradient not mentioned.
a)
Let's dissect this systematically. First, the acid-base disturbance
So, there is a high anion gap metabolic acidosis with appropriate respiratory compensation, which is only partly explained by the raised lactate. Scenarios which could explain this are:
The other abnormalities (and explanations) are:
b)
Biochemistry
Imaging
Adrogué, Horacio J., and Nicolaos E. Madias. "Hypernatremia." New England Journal of Medicine 342.20 (2000): 1493-1499.