Heparin Dosing
Info
Weight
unit kg lb
Height
unit in cm
Heparin Bolus dosing (U/kg) 50 60 70 80 90 100
Heparin Infusion dosing (U/kg/hr) 10 11 12 13 14 15 16 17 18 19 20
R e s u l t s
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Actual Body Weight (kg)
 
Heparin Bolus for Actual Weight (Units)
 
Heparin Infusion for Actual Weight (Units/hr)
 
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Info
Heparin Dosing

Heparin is dosed based upon an initial loading dose (most commonly 70-80 Units/kg) followed by an infusion (most commonly 15-18 U/kg/hour).  For some indications, the initial bolus may be limited to a maximum (for example with thrombolytics for acute myocardial infarction, the maximum bolus is 4000 Units).

 

The ACCP 2000 Consensus for dosing adjustments (after an initial loading dose of 80 U/kg and maintenance of 18 U/kg/hr) is based upon the APTT which should be done 6 hours into this protocol:

APTT (seconds) ,  Dose change (U/kg/hr) ,  Additional action needed ,  When to check next APTT

  • <35 (1.2xnormal), +4 , Rebolus 80 U/kg, 6 hours
  • 35-45 (1.2-1.5xnormal), +2, Rebolus 40 U/kg, 6 hours
  • 46-70 (1.5-2.3xnormal), 0, None, 6 hours*
  • 71-90 (2.3-3.0xnormal), -2, None, 6 hours
  • >90 (>3xnormal), -3, Stop infusion x 1 hour, 6 hours

*Can be checked every morning after being stable after the first 24 hours if APTT between 46-70 seconds.

 

In the obese patient [(>30% over Ideal Body Weight(IBW)] some have suggested use of an Adjusted Body Weight (ABW) versus actual body weight.  The formula most commonly used for ABW is:

ABW=IBW+0.4(actual weight-IBW)

 

To determine IBW, we use the 2005 IBW formula of Lemmens, et al.

IBW (kgs) = 22 x (height in meters) 2

 

However, caution should be used in adjusting from actual body weight as the findings of Spruill, et al., were that infusion rates and dosing in the obese seem to be well predicted by actual body weight.  In the severely obese, some adjust of weight downward, however may be required as one report of a patient of IBW 50 kgs who was actually 182 kgs did well with a adjustment of weight to calculate the dosing of 120 kgs.

 

Reference:

Hyers TM, et al. Antithrombotic Therapy for Venous Thromboembolic Disease. Chest. 2001;119:176S-193S.

Lemmens HJ, et al. Estimating Ideal Body Weight - A New Formula. Obesity Surgery. 2005 August;15(7):1082-3.

Schwiesow SJ, et al. Use of a Modified Dosing Weight for Heparin Therapy in a Morbidly Obese Patient. Ann Pharmacotherapy. 2005;39(4):753-6.

Spruill WJ, et al. Achievement of anticoagulation by using a weight-based heparin dosing protocol for obese and nonobese patients. Am J Health Syst Pharm. 2001 Nov 15;58(22):2143-6.

Wurtz R, et al. Antimicrobial dosing in obese patients. Clin Infect Dis. 1997;25:112-118.