What are the causes of green-colored serum?

Green Serum: Causes and Clinical Significance

Green-colored serum is most commonly caused by elevated ceruloplasmin levels (particularly during pregnancy), oral contraceptive use, or propofol administration, and typically does not interfere with most laboratory test results or indicate serious pathology.

Primary Causes

Pregnancy-Related

• Elevated ceruloplasmin is the classical explanation, though green serum can occur in pregnancy even with normal ceruloplasmin levels 1
• Typically appears in mid-to-late pregnancy (around 25th week documented) 1
• Serum returns to normal yellow color postpartum
• The exact mechanism beyond ceruloplasmin elevation remains incompletely understood 1

Oral Contraceptive Use

• Female donors taking oral contraceptives frequently produce green-colored plasma 2, 3
• These donors tend to be younger (median age 27 years) with fewer pregnancies 2
• Interestingly, green plasma from these donors demonstrates superior hemostatic properties compared to standard plasma, with higher coagulation factor levels (II, VII, IX, X, fibrinogen) and more hypercoagulable thrombelastography profiles 2, 3

Medication-Related

• Propofol infusion is a well-recognized cause in critical care settings
• Other medications may contribute but are less commonly documented

Post-Transplant/Critical Illness

• Green discoloration has been documented in multivisceral organ transplant patients 4
• May reflect complex metabolic alterations in critically ill patients

Laboratory Testing Implications

Critical point: Despite the alarming appearance, green serum causes minimal interference with most routine laboratory analyses 4.

Tests Typically Unaffected:

• Hematology parameters
• Coagulation studies
• Blood gas analysis
• Most routine clinical chemistry tests 4

Potential Interference:

• Lipemia index may show positive interference, requiring sample dilution 4
• Spectrophotometric assays could theoretically be affected depending on wavelength

Clinical Approach Algorithm

1. Obtain detailed history:

   • Pregnancy status and gestational age
   • Oral contraceptive use
   • Recent propofol or other medication administration
   • Recent organ transplantation or critical illness

2. Verify sample integrity:

   • Rule out hemolysis, lipemia as confounding factors
   • Check for proper collection and handling

3. Selective testing based on context:

   • If pregnant: Check ceruloplasmin (normal range 260-630 mg/L), serum copper
   • If abnormal liver enzymes suspected: ALT, AST, GGT, bilirubin (typically normal in green serum cases) 1
   • Document that green color alone does not indicate pathology

4. Proceed with laboratory testing:

   • Most tests can be run on native sample
   • Dilute sample only if lipemia index flags positive interference 4
   • Document green color in laboratory notes

Common Pitfalls to Avoid

• Do not automatically discard green serum samples - they are usually suitable for analysis 4, 5
• Do not assume liver disease - liver enzymes and bilirubin are typically normal in green serum cases 1
• Do not delay urgent testing - green color does not preclude emergency laboratory analysis 4
• In blood banking, recognize that green plasma units have historically been discarded but may actually have superior hemostatic properties 2, 3

When to Investigate Further

Green serum warrants additional workup only when accompanied by:

• Abnormal liver function tests
• Clinical signs of liver disease or hemolysis
• Unexplained coagulopathy
• Symptoms suggesting copper metabolism disorders (rare)

In isolated green serum with normal clinical context (pregnancy, oral contraceptives), reassurance is appropriate and extensive investigation is unnecessary 1.