Workup of Declining Hemoglobin, Hematocrit, and RBC Count
When a patient presents with declining hemoglobin, hematocrit, and red blood cell count, a systematic diagnostic approach is essential to identify the underlying cause before initiating any treatment. This approach should focus on identifying correctable causes of anemia to guide appropriate management.
Initial Diagnostic Evaluation
Essential Laboratory Tests:
- Complete blood count with differential
- Peripheral blood smear examination
- Iron studies (serum iron, ferritin, total iron-binding capacity, transferrin saturation)
- Vitamin B12 and folate levels
- Reticulocyte count
- Renal function tests (BUN, creatinine)
- Liver function tests
- Coagulation profile (PT, PTT, INR)
Additional Targeted Tests Based on Clinical Suspicion:
- Hemolysis workup (LDH, haptoglobin, direct/indirect bilirubin)
- Coombs test for patients with lymphoproliferative disorders or autoimmune disease 1
- Erythropoietin levels in suspected renal disease or myelodysplasia 1
- Bone marrow examination if myelodysplastic syndrome or bone marrow failure is suspected
- Occult blood testing (stool, urine)
- Endoscopic evaluation for GI sources of blood loss
Assessment for Blood Loss
External Blood Loss:
- Gastrointestinal bleeding (melena, hematochezia, hematemesis)
- Genitourinary bleeding (hematuria, menorrhagia)
- Epistaxis or other visible bleeding sites 1
Internal Blood Loss:
- Retroperitoneal bleeding
- Intramuscular hematomas
- Hemothorax/hemoperitoneum
Management Based on Severity and Cause
Transfusion Thresholds:
- For most stable patients without cardiovascular disease: transfuse when hemoglobin < 7 g/dL 1
- For patients with acute coronary syndrome or cardiac disease: consider transfusion when hemoglobin < 8 g/dL 1, 2
- For patients with symptomatic anemia or poor functional tolerance: consider transfusion at higher thresholds (9-10 g/dL) 1
Specific Treatments Based on Etiology:
- Iron deficiency: oral or IV iron supplementation
- B12/folate deficiency: appropriate vitamin replacement
- Renal insufficiency: consider erythropoiesis-stimulating agents after ruling out other causes 1
- Hemolysis: treat underlying cause (autoimmune, microangiopathic, etc.)
- Bone marrow disorders: disease-specific therapy
Special Considerations
Patients on Anticoagulation:
- Assess for occult bleeding
- Consider temporary dose adjustment or reversal agents if active bleeding 1
- Consult with the primary service managing anticoagulation before making changes 1
Myelodysplastic Syndromes:
- Consider erythropoiesis-stimulating agents if serum erythropoietin < 500 U/L 1
- Consider iron chelation therapy in transfusion-dependent patients 1
Critical Illness:
- Maintain restrictive transfusion strategy (Hb < 7 g/dL) in most critically ill patients 1
- Monitor for signs of inadequate oxygen delivery (elevated lactate, low pH, low central venous oxygen saturation) 1
Pitfalls to Avoid
Failing to investigate the underlying cause before treatment - Simply transfusing without determining etiology can mask important diagnoses 2
Overlooking non-anemic causes of symptoms - Fatigue, dyspnea, and other symptoms may have multiple etiologies
Inappropriate use of erythropoiesis-stimulating agents - These carry thromboembolic risks, particularly in patients with cardiovascular disease or cancer 1, 2
Overtransfusion - Transfusing beyond necessary hemoglobin targets increases risks without providing additional benefit 2
Misinterpreting hemodilution - Intravenous fluid administration can cause apparent decreases in hemoglobin without true anemia 1
Overlooking functional iron deficiency - Consider iron supplementation even with normal ferritin if transferrin saturation is <20% 2
By following this systematic approach to declining hemoglobin, hematocrit, and RBC count, clinicians can efficiently identify the underlying cause and implement appropriate treatment strategies to address both the anemia and its etiology.