What are the limitations of the hep score?

While the hep score is highly validated, it should not replace clinical judgment. OpiCalc provides the latest evidence-based limitations for the hep score to ensure safe bedside use and optimal diagnostic accuracy.

How does the hep score compare to other Hematology scores?

The hep score is a gold-standard diagnostic tool. OpiCalc provides side-by-side clinical guidance to help clinicians choose the most specific evidence-based tool for their patient's presentation.

Is the hep score free to use?

Yes. OpiCalc provides the hep score completely ad-free and optimized for mobile bedside use, ensuring you can calculate medical risk swiftly and without distraction.

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HEP Score

HEP Score vs 4T: Expert-derived probability for HIT. Includes negative modifiers (penalties) for alternative causes like sepsis or liver disease.

Diagnostic Criteria

HIT Probability Result

0

Clinical Risk Class

Low

HIT effectively ruled out (NPV ~100%).

Guidelines & Evidence

Clinical Details

Section 1

When to Use

Evaluating patients with suspected Heparin-Induced Thrombocytopenia (HIT).

Selecting patients who require specialized HIT testing (PF4 ELISA or SRA).

More accurate than the 4T score for clinicians in specialty contexts.

Exclusions

Do not use as a standalone diagnosis. Always correlate with the Presence/Absence of anti-PF4 antibodies.

Section 2

Formula & Logic

Points Calibration

Category	Condition	Points
Platelet Fall	30-50% fall (or nadir 10-19)	1
	> 50% fall (or nadir < 10)	2
Timing	Days 5-14 of heparin	3
	Recent heparin (within 30d)	1
Thrombosis	New proven thrombosis	2
	Skin necrosis	2
Other Causes	Sepsis, DIC, Liver disease	-1 to -3

Pretest Thresholds

< 2 points: HIT ruled out (NPV ~100%).

2 - 4 points: Intermediate risk.

≥ 5 points: High risk (requires urgent PEX/Switch to non-heparin anticoagulation).

Section 3

Pearls/Pitfalls

HEP vs 4T

The HEP score was developed by 13 HIT experts to improve the performance of the 4T score, particularly in complex ICU patients. It includes additional modifiers like the type of heparin used and systemic inflammatory reactions.

Section 4

Evidence Appraisal

Primary Strategy

Development and validation of a predictive score for heparin-induced thrombocytopenia (HIT).

Linkins LA et al. • Blood. 2015;126(10):1238-1244.

View Source

Section 5

Literature

History

Derived from a multicenter prospective study to reduce the high false-positive rate of the clinical diagnosis of HIT.

Last Comprehensive Review: 2026

Guidelines & Evidence

Clinical Details

Section 1

When to Use

Evaluating patients with suspected Heparin-Induced Thrombocytopenia (HIT).

Selecting patients who require specialized HIT testing (PF4 ELISA or SRA).

More accurate than the 4T score for clinicians in specialty contexts.

Exclusions

Do not use as a standalone diagnosis. Always correlate with the Presence/Absence of anti-PF4 antibodies.

Section 2

Formula & Logic

Points Calibration

Category	Condition	Points
Platelet Fall	30-50% fall (or nadir 10-19)	1
	> 50% fall (or nadir < 10)	2
Timing	Days 5-14 of heparin	3
	Recent heparin (within 30d)	1
Thrombosis	New proven thrombosis	2
	Skin necrosis	2
Other Causes	Sepsis, DIC, Liver disease	-1 to -3

Pretest Thresholds

< 2 points: HIT ruled out (NPV ~100%).

2 - 4 points: Intermediate risk.

≥ 5 points: High risk (requires urgent PEX/Switch to non-heparin anticoagulation).

Section 3

Pearls/Pitfalls

HEP vs 4T

Section 4

Evidence Appraisal

Primary Strategy

Development and validation of a predictive score for heparin-induced thrombocytopenia (HIT).

Linkins LA et al. • Blood. 2015;126(10):1238-1244.

View Source

Section 5

Literature

History

Derived from a multicenter prospective study to reduce the high false-positive rate of the clinical diagnosis of HIT.

Last Comprehensive Review: 2026

Related Hematology Tools

ISTH Non-Overt DIC Score

Mixing Study Interpretation

Age-adjusted D-dimer Threshold

sPESI

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HEP Score

HEP Score vs 4T: Expert-derived probability for HIT. Includes negative modifiers (penalties) for alternative causes like sepsis or liver disease.

Diagnostic Criteria

HIT Probability Result

0

Clinical Risk Class

Low

HIT effectively ruled out (NPV ~100%).

Guidelines & Evidence

Clinical Details

Section 1

When to Use

Evaluating patients with suspected Heparin-Induced Thrombocytopenia (HIT).

Selecting patients who require specialized HIT testing (PF4 ELISA or SRA).

More accurate than the 4T score for clinicians in specialty contexts.

Exclusions

Do not use as a standalone diagnosis. Always correlate with the Presence/Absence of anti-PF4 antibodies.

Section 2

Formula & Logic

Points Calibration

Category	Condition	Points
Platelet Fall	30-50% fall (or nadir 10-19)	1
	> 50% fall (or nadir < 10)	2
Timing	Days 5-14 of heparin	3
	Recent heparin (within 30d)	1
Thrombosis	New proven thrombosis	2
	Skin necrosis	2
Other Causes	Sepsis, DIC, Liver disease	-1 to -3

Pretest Thresholds

< 2 points: HIT ruled out (NPV ~100%).

2 - 4 points: Intermediate risk.

≥ 5 points: High risk (requires urgent PEX/Switch to non-heparin anticoagulation).

Section 3

Pearls/Pitfalls

HEP vs 4T

Section 4

Evidence Appraisal

Primary Strategy

Development and validation of a predictive score for heparin-induced thrombocytopenia (HIT).

Linkins LA et al. • Blood. 2015;126(10):1238-1244.

View Source

Section 5

Literature

History

Derived from a multicenter prospective study to reduce the high false-positive rate of the clinical diagnosis of HIT.

Last Comprehensive Review: 2026

Guidelines & Evidence

Clinical Details

Section 1

When to Use

Evaluating patients with suspected Heparin-Induced Thrombocytopenia (HIT).

Selecting patients who require specialized HIT testing (PF4 ELISA or SRA).

More accurate than the 4T score for clinicians in specialty contexts.

Exclusions

Do not use as a standalone diagnosis. Always correlate with the Presence/Absence of anti-PF4 antibodies.

Section 2

Formula & Logic

Points Calibration

Category	Condition	Points
Platelet Fall	30-50% fall (or nadir 10-19)	1
	> 50% fall (or nadir < 10)	2
Timing	Days 5-14 of heparin	3
	Recent heparin (within 30d)	1
Thrombosis	New proven thrombosis	2
	Skin necrosis	2
Other Causes	Sepsis, DIC, Liver disease	-1 to -3