Lab case 25 – Interpretation

A 22 year old female with severe hypochloraemic, hypokalaemic compensated metabolic alkalosis. She has moderate hyponatraemia, volume depletion (high Urea, lactate). There is also mild hypercalcaemia.

Causes include:

1. Medical –  Hyperemesis Gravidarum, UTI, Hepatitis, Gastroenteritis,

2. Surgical – Peptic Ulcer disease, Appendicitis, Cholecystitis, torsion Ovarian cyst, Pancreatitis

3. Drug withdrawal

4. Other – DKA (glucose normal)

She requires resuscitation with normal saline, correction of hypokalaemia (add magnesium), Thiamine and Vit B6 (if hyperemesis), anti emetics, analgesia and treatment of underlying cause.

ph – 7.53, HCO 52, BE 26 => severe metabolic alkalosis


Expected CO2 =  0.7 X HCO3 + 20 = 56mmHg

Actual CO2 = 62 (venous sample) => adequate compensation

Anion gap =  6, low normal, however expect some acidosis (high lactate, possible ketoacidosis)

Osmolality = 274 – low, volume depletion from vomiting.

Calcium slightly elevated, concentration effect. (Hyperemesis is rarely associated with hyperPTH).