Anemia in hospitalized adults: workup and approach
New or worsening anemia in hospital: first exclude bleeding and hemolysis, then classify by MCV and reticulocyte count. Transfuse by restrictive thresholds and symptoms, treat iron deficiency (often IV iron in hospital), and reduce iatrogenic blood loss.
Presenting complaint
Adult · US guidelines
Draft · awaiting physician review
01Orient
What's new in the evidence
- AABB 2023 international guidelines: transfuse stable hospitalized adults at hemoglobin <7 g/dL (7.5 for cardiac surgery, 8 for orthopedic surgery or preexisting cardiovascular disease)
- Cochrane 2025: restrictive and liberal strategies have similar 30-day mortality
- AGA 2024: IV iron when oral iron fails, absorption is impaired or losses are ongoing; prefer formulations that replete in 1–2 infusions; skip diphenhydramine premedication
Differential diagnoses
- Acute blood loss (GI, retroperitoneal, procedural) (can't miss)
- Hemolysis: autoimmune, microangiopathic (TTP/HUS, DIC), drug-induced, G6PD (can't miss)
- Iron deficiency, anemia of inflammation, CKD
- B12 or folate deficiency, alcohol, liver disease, hypothyroidism
- Marrow failure or infiltration (MDS, leukemia, myeloma)
- Phlebotomy and hemodilution
02Assess
Risk scores and decision tools
- MCV (micro, normo, macrocytic) and reticulocyte production index
- Ferritin <30 ng/mL (or <100 with inflammation and TSAT <20%) for iron deficiency
- Hemolysis panel: LDH, haptoglobin, indirect bilirubin, smear, DAT
Key history questions
- Bleeding: melena, hematochezia, hematuria, menorrhagia
- Anticoagulant, antiplatelet and NSAID use
- Symptoms: dyspnea, chest pain, dizziness
- Diet, alcohol, bariatric surgery, malabsorption
- Prior anemia and baseline hemoglobin; CKD, cancer, autoimmune disease
Examination findings
- Hemodynamics, orthostatics
- Pallor, jaundice, splenomegaly, lymphadenopathy
- Rectal exam for melena
- Neuropathy (B12), glossitis, koilonychia
03Investigate
Initial investigations
- CBC with MCV and RDW, reticulocyte count, peripheral smear
- Iron studies (ferritin, iron, TIBC, transferrin saturation), B12, folate
- LDH, haptoglobin, bilirubin, DAT if hemolysis suspected
- BMP, LFTs, TSH; type and screen
Advanced investigations
- Endoscopy/colonoscopy for iron deficiency without an obvious source
- SPEP and free light chains; bone marrow biopsy for unexplained cytopenias
- CT for retroperitoneal bleed after procedures or on anticoagulation
04Treat
Immediate management
- Hemorrhage: resuscitation, transfusion and source control
- Transfuse one unit at a time for stable patients, then reassess
First-line treatment
- Restrictive transfusion thresholds: Hb <7 g/dL (8 g/dL with cardiovascular disease or orthopedic surgery); transfuse for symptoms regardless
- Iron deficiency: IV iron in hospital if oral iron is not tolerated, ineffective, or recovery needs to be fast (e.g., ferric carboxymaltose, ferric derisomaltose, ferumoxytol, iron sucrose)
- B12 1000 mcg IM or high-dose oral; folate 1 mg daily
- Reduce phlebotomy: small-volume tubes, avoid daily routine labs
Second-line treatment
- Erythropoiesis-stimulating agents for CKD or chemotherapy anemia per guidelines
- Autoimmune hemolysis: prednisone 1 mg/kg with hematology
- Microangiopathic hemolysis with thrombocytopenia: treat as TTP until excluded
Specialist referrals
- Gastroenterology for suspected GI loss
- Hematology for hemolysis, unexplained cytopenias or marrow disease
05Disposition
Admission criteria
- Active bleeding, hemodynamic instability, symptomatic anemia needing transfusion
- Hemolysis or new pancytopenia
Safe discharge criteria
- Stable hemoglobin, cause identified or outpatient workup arranged
- Iron replacement plan and follow-up CBC
Follow-up timing
- CBC in 1–2 weeks; ferritin and hemoglobin 4–8 weeks after IV iron
Patient instructions
- Take oral iron once daily or every other day for better absorption
Monitoring
- Daily CBC only if clinically indicated
- Signs of bleeding
Clinical pearls and pitfalls
- Hospital-acquired anemia from phlebotomy is common and preventable
- Ferritin is an acute-phase reactant; use TSAT and context in inflammation
- Each unit of RBCs raises hemoglobin by about 1 g/dL in an adult without ongoing loss
RefGuidelines and landmark evidence
- GuidelineAABB – Red Blood Cell Transfusion: International Guidelines (2023)PubMed
- GuidelineAGA – Clinical Practice Update on Management of Iron Deficiency Anemia (2024)PubMed
- TrialTRICC: restrictive vs liberal transfusion in critical care (1999)PubMed
- ReviewCochrane – Transfusion thresholds for guiding red blood cell transfusion (2025)PubMed
For education only. Typical adult starting points; confirm doses against renal function, allergies, interactions and your institution's protocols. Not a substitute for clinical judgment or senior review.