Comprehensive Blood Investigation Components
A comprehensive blood investigation should include complete blood count (CBC), blood chemistry profile, coagulation studies, and specialized tests based on clinical suspicion, with additional targeted testing determined by patient presentation and suspected conditions.
Core Components of a Comprehensive Blood Investigation
Complete Blood Count (CBC)
- CBC should include hemoglobin, hematocrit, red blood cell count, white blood cell count with differential, and platelet count 1, 2
- CBC evaluation provides critical information about oxygen-carrying capacity, immune system function, and can help diagnose anemia, infections, and certain cancers 2
- Red cell indices (MCV, MCH, MCHC) and red cell distribution width (RDW) should be included as they can predict cardiovascular disease risk and metabolic disorders 3
Blood Chemistry Profile
- Basic metabolic panel should include electrolytes, renal function (creatinine, eGFR), and random glucose or hemoglobin A1c 1
- Liver function tests should be included to assess hepatic status, especially when evaluating for systemic conditions 1
- Serum calcium, phosphorus, and alkaline phosphatase should be included to evaluate bone metabolism when clinically indicated 1
Coagulation Studies
- Coagulation panel should include prothrombin time (PT), activated partial thromboplastin time (aPTT), international normalized ratio (INR), and fibrinogen 1
- D-dimer should be considered when evaluating for disseminated intravascular coagulation or thrombotic conditions 1
Cardiac Markers
- Cardiac biomarkers including troponin should be included when cardiovascular disease is suspected 1
- Consider creatine kinase and other cardiac enzymes when evaluating for cardiac injury 1
Specialized Testing Based on Clinical Context
Hematologic Malignancy Workup
- For suspected hematologic malignancies, include immunophenotyping, cytogenetic studies, and molecular testing 1
- Flow cytometry and bone marrow examination may be necessary for definitive diagnosis of leukemias and lymphomas 1
Infectious Disease Evaluation
- Blood cultures should be included when infection is suspected 1
- Specific serologic tests for suspected pathogens (e.g., parvovirus B19, cytomegalovirus, toxoplasmosis) should be included based on clinical presentation 1
Inflammatory Markers
- C-reactive protein and/or procalcitonin should be included when evaluating for systemic inflammation or infection 1
- Erythrocyte sedimentation rate may provide additional information about inflammatory processes 4
Metabolic Assessment
- Lipid profile (fasting or non-fasting) should be included for cardiovascular risk assessment 1
- Consider hemoglobin A1c or glucose tolerance testing when diabetes is suspected 1
Special Considerations
Pediatric Patients
- For pediatric patients with suspected physical abuse, consider specialized testing for bone metabolism including serum calcium, phosphorus, alkaline phosphatase, parathyroid hormone, and vitamin D 1
- In cases of unexplained bruising, include complete coagulation studies including factor VIII, IX, and von Willebrand activity 1
Stroke Evaluation
- For patients with suspected stroke, include initial bloodwork with CBC, electrolytes, coagulation studies, renal function, random glucose or HbA1c, and troponin 1
- ECG monitoring should accompany blood testing to detect cardiac arrhythmias 1
Oncology Patients
- For patients with suspected leukemia, comprehensive genetic and molecular testing should be performed, including karyotyping, FISH, and RT-PCR for recurrent genetic abnormalities 1
- HLA typing should be considered early in the workup of hematologic malignancies when stem cell transplantation might be an option 1
Common Pitfalls and Caveats
- Avoid ordering tests in isolation; interpret CBC findings in conjunction with clinical presentation and other laboratory results 4, 5
- Be aware that timing of blood collection can affect certain parameters, particularly those influenced by diurnal variation 6
- Remember that abnormal values must be interpreted in the context of the patient's baseline, as what is abnormal for one patient may be normal for another 4
- Consider the impact of medications on blood test results, particularly anticoagulants, chemotherapeutic agents, and immunosuppressants 2