Pre-operative anaemia

 

Summary:

Definition

·      <130g/L men

·      <120g/L women

·      <110g/L pregnant

Anaemia is common

In major elective surgery patients:

·      33% anaemic

·      20% not anaemic but iron deficient

Anaemia is harmful

·      ↑Infection

·      ↑Thrombotic events

·      ↑Blood transfusion

·      ↑Mortality

(even iron deficiency without anaemia is bad)

Transfusion is harmful

·      Adverse reactions

·      Wound infection

·      Pneumonia

·      Sepsis

·      Cardiac event

·      Death

Transfusion is preventable

·      Iron

·      Vit B12

·      Folate

·      Epo

 

Classification:

Microcytic

·      **Iron deficiency**

o  Dx: Fn <30, or Fn <100 with CRP >5, TF Sat <20, ↑Retic

o  Ax: gastroscopy and colonoscopy

o  Rx: IV iron polymaltose ~1.5g

o  Calculate by weight and Hb increment

o  Takes 3/52 to restore Hb

·      Thalassaemia

o  Very low MCV

Normocytic

·      **Chronic disease**

o  Dx: context

·      Organ failure (bone marrow, kidney, liver, thyroid)

o  Dx: UEC, LFT, TFT, +/- marrow biopsy

o  Rx: Epo in renal failure

Macrocytic

·      B12 or folate deficiency

o  Dx: serum B12, RBC folate

o  Rx:replace

·      Alcohol

 

Investigation:

Erythrocytes

·      MCV

·      RCDW

·      MCH

·      Reticulocyte count

·      Reticulocyte Hb

Haematinics

·      Iron

·      Ferritin

·      Transferrin saturation

·      B12

·      Folate

Organs

·      UEC

·      LFT

·      TFT

·      Bone marrow biopsy

Inflammation

·      CRP

Referral

·      Gastro (if needing scopes)

·      Haem (if not iron deficiency or chronic disease)

·      Renal (if needing Epo)

 

Functional iron deficiency:

Normal physiology

·      Absorbed in duodenum

·      Stored as ferritin in enterocytes, macrophages, hepatocytes

·      Exported by ferroportin in absence of hepcidin

·      Circulates bound to transferrin, available for erythropoiesis

Pathophysiology

·      Systemic inflammation or organ dysfunction

·      ↑Hepcidin, ↑Ferritin

·      ↓Absorption, ↓release, ↑sequestering

·      Hence iron unavailable for erythropoiesis

Biochemical profile

·      Ferritin <30   OR   30-100 with ↑CRP

·      Transferrin saturation <20%

·      ↓MCV

·      ↑RCDW

·      ↓Reticulocyte Hb

 

 

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