Case 4

19 year old female

C/o abdominal pain and vomiting for 3 days.
No past medical history of note

O/e BP 90/55, HR 120/min
Abdomen soft

Basic blood investigations as below:

FBC : TWC 16,000, Hb 12.1, Platelets 227

U/E : Na 131, K 3.1, Cl 97, Bicarb 12, Creatinine 108

What simple test would give you the diagnosis?
How would you manage this patient?


Answer : Capillary blood glucose

The most striking abnormality in the blood tests is the low bicarbonate level of 12 mmol/L (usual range 22-30). This implies a metabolic acidosis. Next, we can calculate the anion gap (Na + K - Cl - Bicarb) = 131 + 3.1 - 97 - 12 = 25.1. The normal range of the anion gap is usually quoted as 8- 16; hence what we have here is a high anion-gap metabolic acidosis (HAGMA).

Go back to medical school biochemical pathology, and you will (hopefully) remember the causes of HAGMA :

• Diabetic ketoacidosis (DKA)
  
• Severe uremia
• Drugs (salicylate, ethanol, methanol, ethylene glycol)
• Lacticacidosis

In this case, DKA is the most likely diagnosis (assuming no consumption of meds), and a hypocount will reveal a high capillary blood glucose reading. Of course you can do a serum ketone level or an arterial blood-gas (ABG) analysis which will be more definitive, but they take longer for the results to come back.

Approach

• Manage as P1 case - DKA patients may not look apparently ill but they can deteriorate precipitously. Immediate management is needed
• Immediate fluid resuscitation is critical - 1-3 L of normal saline within first hour.
• IV Insulin (usually 5-10 units bolus) followed by IV insulin infusion
• Close monitoring and replacement of electrolytes (esp. K) - remember that insulin shifts K into the cells (hence it is also treatment for hyperkalemia)
• Bicarbonate infusion - not critical as acidosis usually will correct with measures above. Carries risk of cerebral oedema
• Identify and treat underlying cause (e.g. antibiotics for sepsis)
• Admit to Endocrine/ Int Med. May need close monitoring in ICU/ High dependency unit

Remember :

• Patient usually does not have a history of diabetes. Their first presentation will be DKA.
• If not treated in time and aggressively enough, DKA carries a high mortality rate even in a young and apparently healthy individual.

• Not all abdominal pains are surgical in nature!