# Question 24.2

A 40-year-old patient with a background of alcohol abuse presents with a history of 8 days of diarrhoea and vomiting.

The following results are obtained:

 Parameter Patient Value Adult Normal Range Sodium 116 mmol/L* 137 – 146 Potassium 2.9 mmol/L* 3.5 – 5.0 Chloride 67 mmol/L* 95 – 110 Bicarbonate 14 mmol/L* 24 – 31 Urea 2.9 mmol/L* 3.0 – 8.5 Creatinine 46 µmol/L* 60 – 120 Glucose 6.8 mmol/L 3.0 – 7.8 Osmolality 254 mOsm/kg* 274 – 295 Phosphate 0.6 mmol/L* 0.7 – 1.4 Magnesium 0.7 mmol/L 0.7 – 1.05 Calcium corrected 2.3 mmol/L 2.1 – 2.6 Albumin 44 g/L 36 – 52 Bilirubin 13 µmol/L 0 – 18 Aspartate transferase 80 U/L* 0 – 30 Alanine transferase 67 U/L* 0 – 30 Alkaline phosphatase 148 U/L* 30 – 100 g-Glutamyl transferase 480 U/L* 0 – 35

a)    What is the acid-base disturbance in this patient? (20% marks)

b)    What are the likely causes in this context? (30% marks)

a)
Metabolic acidosis- Anion gap= 116-(67+14) = 35 Delta ratio= 23/10=2.3
HAGMA with metabolic alkalosis OR Increased SID

b)
Metabolic alkalosis – due to vomiting- Acid loss and contraction alkalosis. HAGMA-
Lactic acidosis from hypovolaemia or bowel obstruction/sepsis, Ketoacidosis from starvation/alcohol.

## Discussion

In some sort of a structured fashion:

• The bicarbonate is low, suggesting a metabolic acidosis
• The anion gap is (116-67-15) = 34
• The delta ratio is therefore (34-12)/(24-15) =  2.44;
in other words, this is a mixed HAGMA and metabolic alkalosis.
• The calculated osmolality is (116 × 2) + 2.9 + 6.8 = 241.7, and so the osmolar gap is minimal (254-241.7 = 12.3)

Causes of HAGMA appropriate to this scenario include:

• Toxic alcohol ingestion (classically, methanol) - though the low osmolar gap makes this less likely
• Alcohol-induced or starvation-associated ketoacidosis (more likely)
• Lactic acidosis due to the hypovolemic state, and the failure of the liver to metabolise it

The metabolic alkalosis can be attributed to the vomiting and diarrhoea, and more directly to the aldosterone excess which develops in states of volume depletion.