Coagulation:- part 3 – Coagulation Screening, Normal, and Critical values
For the screening of coagulation abnormality, the following tests are advised.
- Platelets count (140,000 to 340,000 /cmm).
- Bleeding time (Ivy method <4 min and Duke method 1 to 4 min).
- Clot retraction qualitative begins in 30 to 60 minutes; it is complete within 24 hours but usually within 6 hours.
- Coagulation time or clotting time (5 to 15 minutes in glass tubes and 19 to 60 minutes in the siliconized tube).
- Fibrinolysins are negative.
- Prothrombin time, one stage (same as control and should be 11 to 16 seconds).
- Thromboplastin generation time (compared to normal control).
- To measure the intrinsic system, advise:
- Activated partial thromboplastin APTT.
- To measure the extrinsic system, advise:
- One stage prothrombin time PT.
The tests advised for coagulation workup with their normal and panic values:
| Test | Normal values | Normal values source (4) | Critical values (source 3) |
| Platelets count | 150.000 to 450,000 /cmm | <100,000 (20,000 /cmm) | |
| Activated partial thromboplastin time (APTT) | 25 to 35 seconds | >40 seconds. | |
| Prothrombin time (PT) | 10 to 13 seconds | >15 seconds | |
| Thrombin time (TT) | 17 to 25 seconds | ||
| Bleeding time (BT) | 2 to 8 minutes | ||
| Clotting time (CT) | 2 to 6 minutes (glass tube 10 to 15 minutes) | ||
| Fibrinogen | 2.0 to 4.0 g/L | <100 mg/dL | |
| Fibrinogen degradation products (FDP) | < 10 mg/L |
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| Plasma D-dimer | < 200 mg/L | <250 µg/L | |
| Coagulation factors | 500 to 1500 U/L | ||
| Factor V% | <35% | ||
| Factor VII | <10% | ||
| Factor VIII | <100% and >160% | ||
| Factor IX | <30% | ||
| Protein C | 70 to 1400 U/L | ||
| Protein S total | 70 to 1400 U/L |
Critical values source 2:
- Platelets = <50,000/cmm or > 1 million/cmm.
- APTT = >70 seconds.
- PTT = >100 seconds.
- Fibrinogen = <100 mg/dL.