Heparin

UW Medicine Standard Protocols – Initiation Dosing

1. Order standard heparin infusion with starting dose defaulted based on the indication.
2. Order Loading Bolus, if warranted.
3. Order goal anti-Xa level (low intensity 0.3-0.5 units/mL or regular intensity 0.3-0.7 units/mL).
4. Order as needed Re-Bolus for subtherapeutic anti-Xa, if warranted.

INDICATION	LOADING BOLUS (maximum 10,000 units)	INITIAL INFUSION DOSE	PRN RE-BOLUS FOR LOW ANTI-Xa LEVEL (maximum 5,000 units)	FIRST ANTI-Xa LEVEL
Treatment of Acute Thrombosis (e.g., DVT, PE)	80 units/kg	18 units/kg/hr	Anti-Xa 0.1-0.29 units/mL: 25 units/kg (Maximum 2,500 units) Anti-Xa < 0.1 units/mL: 50 units/kg (Maximum 5,000 units)	6 hours after starting infusion
Atrial Fibrillation, Valve Replacement, Peri-Procedural Bridging	70 units/kg	15 units/kg/hr
Acute Coronary Syndrome	50 units/kg	12 units/kg/hr
Mechanical Circulatory Support	None	15 units/kg/hr	None
Acute Ischemic Stroke	None	12 units/kg/hr
Ultra Low Intensity Heparin (anti-Xa goal 0.1-0.3)	None	8 units/kg/hr

 

UW Medicine Heparin Infusion Algorithms

Regular/Low-Intensity Heparin Infusion Algorithm

Ultra-Low Intensity Heparin Infusion Algorithm

Mechanical Circulatory Support Heparin Infusion Algorithms

 

Monitoring

Anti-Xa Activity Monitoring

View Guidelines

PTT Levels

PTT may be used to monitor heparin as an alternative to anti-Xa levels in patients with hyperbilirubinemia, hemolysis, hypertriglyceridemia, or direct factor Xa inhibitor use that might interfere with anti-Xa levels.

For HMC and UWMC-ML, click below to see UW Medicine’s Provider Managed Heparin Infusion Using PTT Monitoring Protocol:

UW Medicine Heparin Infusion PTT Algorithm 2019 Provider Managed

*Initial dosing of heparin based on indication can be found here.

For UWMC-NW, contact the pharmacy department and request the pharmacist to place the order in Epic for the NURSE Managed Heparin Infusion Using PTT Monitoring Protocol.

 

DOAC to Heparin Transition

DOAC to Heparin Transition Guidelines

 

Full Intensity SQ Heparin

Guidelines for Fixed Dose, Full Intensity SQ Heparin

• Unfractionated heparin (UFH) 250 units/kg SQ q12h with no aPTT monitoring
• Consider 333 units/kg SQ loading dose for treatment of acute thrombosis
• Do not use for treatment of arterial thrombosis (eg. AF, valve replacement, etc.)

Guidelines for Adjusted Dose, Full Intensity SQ Heparin

 

Initial Dosing

Starting therapy with adjusted-dose SQ heparin

• Give UHF 240 units/kg SQ x 1
• Check aPTT 6 hours after first dose
• Adjust dosing according to chart below

Converting from continuous infusion heparin to adjusted dose SQ heparin

• Calculate 24hr dosing requirement necessary to maintain therapeutic PTT
• Divide into two q12h doses
• Discontinue IV heparin and administer first SQ dose within 1 hour
• Check first PTT 6 hours after first dose
• Adjust dosing according to chart below

Converting from warfarin to adjusted dose SQ heparin

• Discontinue warfarin
• Give heparin 240 units/kg SQ when INR < lower limit of therapeutic range
• Check aPTT 6 hours after first dose
• Adjust dosing according to chart below

 

Maintenance Dosing Adjustments

PTT (sec)	Dosing Adjustment (round to nearest 500 units)	Next PTT
< 40	increase by 36 - 48 units/kg q12h	6 hours after a dose in 1-3 days
40 - 59	increase by 24 - 36 units/kg q12h	6 hours after a dose in 1-3 days
60 - 100	no change	q4-7 days (6 hours after a dose)
101 - 120	decrease by 6 - 12 units/kg q12h	6 hours after a dose in 1-3 days
121 - 140	decrease by 12 - 24 units/kg q12h	6 hours after a dose in 1-3 days
> 140	decrease by 24 - 36 units/kg q12h	6 hours after a dose in 1-3 days

Therapeutic Monitoring

• Baseline:  CBC, PT/INR, PTT
• First 2 weeks of therapy:  CBC q2-3 days
• Chronic therapy: CBC q1-3 months