Is HemoCel (hydroxyethyl starch) used as a replacement fluid in plasma exchange for patients with Thrombotic Thrombocytopenic Purpura (TTP)?

HemoCel (Hydroxyethyl Starch) is NOT Used as Replacement Fluid in TTP Plasma Exchange

Fresh frozen plasma (FFP) or cryoprecipitate-poor plasma (also called cryosupernatant) are the standard replacement fluids for plasma exchange in TTP—not HemoCel or any other colloid solutions. 1

Standard Replacement Fluids for TTP

The established replacement fluids for therapeutic plasma exchange in TTP are:

• Fresh frozen plasma (FFP) - This is the most widely used and accepted replacement fluid, containing ADAMTS13 enzyme needed to cleave von Willebrand factor multimers 1, 2

• Cryoprecipitate-poor plasma (cryosupernatant) - Plasma with cryoprecipitate removed, which is relatively deficient in large von Willebrand factor multimers and may be more effective than FFP in some cases 3, 4

• Albumin combined with plasma - Some centers use albumin plus FFP or mixed plasma formulations (such as 2:1:1 ratio of albumin:FFP:cryoprecipitate-reduced plasma) with comparable efficacy 5

Why HemoCel Cannot Be Used

HemoCel (hydroxyethyl starch) is a synthetic colloid used for volume expansion, not a source of coagulation factors or ADAMTS13 enzyme. The pathophysiology of TTP requires replacement of ADAMTS13, which is only present in plasma products. 1

Key reasons HemoCel is inappropriate:

• Lacks ADAMTS13 enzyme - TTP is caused by deficiency of ADAMTS13 activity, requiring replacement with plasma containing this enzyme 1, 2

• No coagulation factors - Synthetic colloids do not contain the coagulation factors present in plasma 1

• Wrong therapeutic mechanism - Volume expansion alone does not address the underlying pathology of TTP 1

Treatment Algorithm for TTP

When TTP is suspected based on thrombocytopenia and microangiopathic hemolytic anemia:

1. Initiate plasma exchange immediately with FFP as replacement fluid (1-1.5 plasma volumes daily) 1, 2

2. Add high-dose glucocorticoids concurrently with plasma exchange 1

3. Continue daily plasma exchange until platelet count >150×10⁹/L and LDH normalizes, then taper slowly 2

4. Consider cryosupernatant if patient fails to respond to FFP after approximately 7 exchanges 3, 4

5. Add rituximab and/or caplacizumab for refractory cases or confirmed severe ADAMTS13 deficiency 1

Common Pitfall to Avoid

Do not delay plasma exchange while waiting for ADAMTS13 results in adults with suspected TTP. If the PLASMIC score indicates intermediate-to-high risk, start plasma exchange and glucocorticoids immediately. 1 In children, TTP is less common and plasma exchange carries more morbidity, so it is acceptable to wait 24-48 hours for ADAMTS13 confirmation. 1