The stem
A 67-year-old man has three weeks of painless, progressive jaundice, with dark urine and pale stools.
Laboratory reportSpecimen: blood
| Test | Result | Units | Reference |
|---|---|---|---|
| Total bilirubin | 12.4 H | mg/dL | 0.0 – 1.1 |
| Direct bilirubin | 9.8 H | mg/dL | 0.0 – 0.3 |
| Alkaline phosphatase (ALP) | 612 H | U/L | 35 – 105 |
| GGT | 845 H | U/L | 5 – 36 |
| ALT | 96 H | U/L | 0 – 41 |
| AST | 78 H | U/L | 0 – 40 |
| Albumin | 3.5 L | g/dL | 3.8 – 4.4 |
| INR | 1.6 H | 0.8 – 1.2 |
Reference ranges: hospital laboratory (General Lab), except INR (typical range).
The examiner’s questions
Question 1What pattern do these results show?Show the model answer
An obstructive (cholestatic) pattern. The bilirubin is mainly direct (conjugated), and the ALP and GGT are raised far more than the ALT and AST. The R-factor, (ALT ÷ its upper limit) ÷ (ALP ÷ its upper limit), is about 0.4; a value below 2 indicates cholestasis.
Question 2Why is the GGT useful alongside the ALP?Show the model answer
ALP also comes from bone. A raised GGT confirms that the ALP is coming from the liver and bile ducts.
Question 3Why is the INR raised, and how do you correct it?Show the model answer
With no bile reaching the gut, fat-soluble vitamin K is not absorbed and the clotting factors that depend on it fall. Intravenous vitamin K corrects the INR within a day or two if the liver itself is working, and must be given before any procedure.
Question 4What is your next investigation?Show the model answer
Abdominal ultrasound to look for dilated bile ducts and the level of the block, then CT of the pancreas. CA 19-9 as a baseline.
After you answerThe teaching pointShow
In obstruction the enzymes that line the ducts (ALP, GGT) rise most. In hepatitis the enzymes inside liver cells (ALT, AST) rise most.
The patients and results are written for teaching and do not belong to real patients.