Should blood work be done?

Blood Work Recommendations for Clinical Practice

Blood work should be performed selectively based on specific clinical indications rather than as routine practice, with testing choices guided by patient history, physical examination findings, and the probability of detecting relevant abnormalities that would change management. 1

When to Order Blood Work

Clinical Indications for Blood Work:

• Suspected bleeding disorders:

  • When evaluating children with bruising/bleeding concerning for abuse, blood tests should be chosen based on:
    • Prevalence of suspected conditions
    • Patient and family history
    • Probability of specific bleeding disorders causing the findings 1
  • Laboratory evaluation is not necessary in many situations given the rarity of most bleeding disorders 1

• Monitoring for malignancy:

  • For specific conditions with high cancer risk (e.g., A-T, NBS):
    • Routine blood work for early detection of hematologic malignancies is no longer recommended 1
    • Prompt evaluation should be performed only when signs/symptoms of leukemia or lymphoma appear 1

• Evaluation of liver function:

  • Initial investigation for potential liver disease should include bilirubin, albumin, ALT, ALP and GGT, with full blood count if not performed within previous 12 months 1
  • AST testing may be added as "reflex" testing to calculate AST:ALT ratio when abnormalities are detected 1

• Medication monitoring:

  • For patients on medications with potential hepatotoxicity (e.g., acitretin):
    • Blood lipid determinations before starting treatment and at 1-2 week intervals until lipid response is established 2
    • Liver function tests should be monitored as approximately 1 in 3 patients may experience elevations 2

When Blood Work Is NOT Recommended:

• Asymptomatic surveillance:

  • In children with A-T, annual blood work is no longer recommended for early detection of hematologic malignancies 1
  • In asymptomatic/healthy children with Noonan Syndrome or related RASopathies, no routine bloodwork is recommended 1

• Excessive frequency:

  • Daily blood tests for hospitalized patients should be ordered only if results would change patient care 3
  • For preoperative testing in healthy patients (ASA I-II), blood tests remain valid for up to 2 months before surgery 4

Practical Considerations for Blood Testing

Specimen Handling:

• Coagulation tests are highly sensitive to specimen handling and should be performed in laboratories experienced with these assays 1
• Inappropriate handling commonly leads to false-positive results 1

Timing Considerations:

• In children with ICH who receive blood product transfusions, screening for bleeding disorders should be delayed until elimination of transfused blood clotting elements 1
• For preoperative testing in healthy patients, blood tests performed within 2 months of surgery provide equivalent safety to more recent testing 4

Special Populations

Patients Refusing Blood Transfusions:

• For patients who refuse blood transfusions (e.g., Jehovah's Witnesses), patient blood management protocols can be implemented:
  • Iron supplementation
  • Subcutaneous erythropoietin
  • Folic acid and vitamin B supplements 5

Patients with Cyanotic Heart Disease:

• Blood work should include:
  • Complete blood count with MCV
  • Serum ferritin (serum iron, transferrin, and transferrin saturation for early detection of iron deficiency)
  • Creatinine, serum uric acid, clotting profile
  • BNP or pro-BNP
  • Folic acid and vitamin B12 (if elevated MCV or normal MCV with low serum ferritin) 1

Cost and Patient Safety Considerations

• Provider education can reduce unnecessary daily blood tests, decreasing healthcare costs and reducing risk of complications such as anemia 3
• Implementation of patient blood management (PBM) practices can improve patient safety and reduce transfusion requirements 6, 7

Common Pitfalls to Avoid

1. Overreliance on testing: No single panel of tests rules out every possible bleeding disorder 1

2. False reassurance: Laboratory testing suggestive of a bleeding disorder does not eliminate abuse from consideration in children with suspicious bruising/bleeding 1

3. Misinterpretation of results: The aPTT can be falsely prolonged in certain circumstances (e.g., lupus anticoagulant) or may not indicate a true bleeding disorder (e.g., factor XII deficiency) 1

4. Unnecessary repeat testing: In healthy patients, repeating blood tests shortly before surgery when results within the past 2 months were normal provides no additional benefit 4

5. Ignoring transient abnormalities: Patients who experience traumatic brain injury often have a transient coagulopathy that does not reflect an underlying congenital disorder 1