Internal Medicine

0521779407-09 CUNY1086/Karliner 0 521 77940 7 June 4, 2007 21:12

674 Hemophilia A and B

■Specific factor assays (FVIII or FIX) show reduced level

■Bethesda assay positive in patients with inhibitory antibodies

differential diagnosis

■For FVIII deficiency

➣R/O von Willebrand’s disease (vWD). Bleeding time is long

in vWD, normal in hemophilia A. Symptoms in vWD suggest

mucosal bleeding, not joint and soft tissue. Autosomal domi-

nant, not X-linked inheritance. FVIII level low, but so are risto-

cetin cofactor (RCF) and vW antigen.

■For FVIII or FIX deficiency

➣Acquired FVIII or FIX inhibitor. No family hx of bleeding. Patient’s

symptoms are recent in onset, not lifelong. APTT prolonged, does

not correct with mix, factor level low, Bethesda assay positive.

management

■Be certain that correct factor deficiency has been identified.

■For serious or life-threatening bleeds (e.g., symptoms that suggest

intracranial or retropharyngeal bleeds), infuse factor to 100%, then

undertake diagnostic studies.

■Early infusion of factor after any bleed reduces morbidity.

■Joint bleeds do not require aspiration unless pain and swelling are

severe or unless sepsis is suspected.

specific therapy

■Management of acute bleeding episodes in severe hemophilia

➣Assess whether bleed is life-threatening (intracranial, retroperi-

toneal. retropharyngeal with compromise of airway, major

trauma, major surgery), major (severe joint or soft tissue bleed,

severe trauma without evidence of bleed, GI bleeding), or minor

(most joint and soft tissue bleeds, epistaxis, dental bleeding).

➣Life-threatening bleeds, replace to 80–100%; major, replace to

50%; minor, to 30%

➣Clotting factor concentrates dosed in units (U) with 1 U defined

as amount of Factor VIII or Factor IX in 1 ml of normal plasma.

To calculate FVIII dose, assume that 1 U/kg raises circulating

level by 2%. To dose 70-kg man to 100% level will require 70

(kg)× 50 =3500 U, and to dose him to 30% will require 70×

15 =1050 U. To calculate FIX dose, assume that 1 U/kg raises

circulating level by 1%, so to dose 70-kg man to 100% requires 70

× 100 =7,000 U. Doses for recombinant FIX (Benefix) require