📋 Reference sheet · Blood count and clotting

INR, PT and APTT: reading a clotting screen

A clotting screen back from the lab. Which pathway each number measures, and when to phone haematology.

One page, every threshold with its number and unit. Reviewed and updated by practising UK GPs. Last reviewed 7 Oct 2026.

This sheet puts the whole decision on one page: the thresholds that change what you do, each with its number and unit, and the sources each one was checked against.

🔒 Sign up free to see the full sheet

You're viewing a free preview. Create a free account to unlock the rest.

Inside the full sheet 🔒 Thresholds, numbers and units 🔒 Sources checked against the guideline

Sample sheets are open to everyone in the Free Sample Bundle.

Related Ocean Article: Oral Anticoagulation · also Haemophilia, Atrial Fibrillation (AF), Purpura and Petechiae, Chronic Kidney Disease (CKD), Cirrhosis. Part of the GP reference sheets, result interpretation one page per test or finding.