A 64-year-old man with a background of heavy alcohol consumption has been admitted to your ICU for several days with a sensitive staphylococcus aureus (MSSA) epidural abscess which has been surgically drained.
The following results were obtained.
Parameter |
Value |
Normal Range |
Sodium |
143 mmol/L |
134 – 146 |
Potassium |
4.0 mmol/L |
3.4 – 5.0 |
Chloride |
114 mmol/L* |
100 – 110 |
Urea |
10.1 mmol/L* |
3.0 – 8.0 |
Creatinine |
104 mmol/L |
50 – 120 |
Glucose |
6.9 mmol/L |
3.0 – 7.0 |
Urinary ketones |
Negative |
|
Measured osmolality |
300 mOsm/Kg |
280 – 300 |
On 30% oxygen arterial blood gas analysis as follows:
Parameter |
Value |
Normal Range |
||
pH |
7.22* |
7.35 |
– 7.45 |
|
PO2 |
84 mmHg (11kPa) |
|||
PCO2 |
25 mmHg (3.2 kPa)* |
35 |
– |
45 (4.6 – 6.0) |
Bicarbonate |
10 mmol/L* |
22 |
– |
27 |
Lactate |
1.8 mmol/L* |
<2.0 |
What is the likely cause of the acid base disturbance?
How would you investigate and manage it?
High anion gap metabolic acidosis secondary to pyroglutamic acidaemia.
Can be detected by requesting an organic acid screen, or by plasma or urine pyroglutamate levels.
Management – cessation of precipitating drugs likely paracetamol and flucloxacillin in this case.
N-Acetyl cysteine infusion has been advocated.
Let us dissect these results systematically.
So, what is making this drunk so acidotic? The lactate is not raised; so the differentials for the high anion gap here would include the following:
Of course, the MSSA story suggests the college want us to consider pyroglutamic acidosis as a cause.
Investigations for these differentials would include the following:
One would want to stop feeding this man the paracetamol and flucloxacillin.
Dempsey GA Lyall HJ, Corke CF, Scheinkestel CD. Pyroglutamic acidemia: a cause of high anion gap metabolic acidosis. Crit Care Med. 2000Jun;28(6):1803-7.
Duewall, Jennifer L., et al. "5-Oxoproline (pyroglutamic) acidosis associated with chronic acetaminophen use." Proceedings (Baylor University. Medical Center) 23.1 (2010): 19.
Akhilesh Kumar and Anand K. Bachhawat Pyroglutamic acid: throwing light on a lightly studied metabolite ,SPECIAL SECTION: CHEMISTRY AND BIOLOGY. CURRENT SCIENCE, VOL. 102, NO. 2, 25 JANUARY 2012. 288