AKT · Haematology/Anaemia & red cell

Haemolytic anaemia

Premature red-cell destruction — inherited (membrane/enzyme/Hb) or acquired (immune/mechanical)

Overview

Anaemia from premature red-cell destruction, with a compensatory reticulocytosis and the biochemical signature of haemolysis (raised LDH and bilirubin, low haptoglobin). Split by site (intra- vs extravascular) and cause: inherited (hereditary spherocytosis, G6PD deficiency, sickle/thalassaemia) vs acquired (autoimmune — warm/cold, mechanical, drug-induced, microangiopathic). The direct antiglobulin test (DAT/Coombs) separates immune from non-immune.

Recognise

Anaemia + jaundice (unconjugated) + splenomegaly; dark urine; raised reticulocytes
Haemolysis screen: HIGH LDH, HIGH unconjugated bilirubin, LOW haptoglobin, raised reticulocytes; film — spherocytes, schistocytes, bite cells, or Heinz bodies by cause
DAT (Coombs) POSITIVE = immune (autoimmune/alloimmune/drug); NEGATIVE = hereditary or mechanical/microangiopathic

Red flags

Microangiopathic haemolysis with thrombocytopenia (schistocytes) → TTP/HUS/DIC — a haematological emergency (TTP → plasma exchange, do NOT give platelets)
Severe autoimmune haemolysis → urgent steroids/transfusion (warm AIHA)

Differentials & how to tell them apart

Hereditary spherocytosisDAT-negative, spherocytes, family history, splenomegaly; EMA binding test

G6PD deficiencyX-linked; oxidative crisis (drugs — primaquine/dapsone, fava beans, infection); bite cells/Heinz bodies

Autoimmune haemolytic anaemiaDAT-positive; warm (IgG, idiopathic/lymphoma/SLE) vs cold (IgM, mycoplasma/EBV)

Microangiopathic (TTP/HUS/DIC)schistocytes + thrombocytopenia — emergency, distinct management

Methaemoglobinaemiachocolate-brown blood + central cyanosis with a SATURATION GAP (low SpO2 but normal PaO2 on ABG) unresponsive to oxygen; causes — dapsone, nitrates/nitrites, local anaesthetics, primaquine; treat with methylene blue (avoid in G6PD)

Schistocytes (red-cell fragments) — microangiopathic haemolysis (blood film)
Prof. Osaro Erhabor / CC0 — Wikimedia Commons

Investigations

FBC + reticulocytes (high), blood FILM (spherocytes/schistocytes/bite cells), LDH (high), bilirubin (unconjugated, high), haptoglobin (low); DIRECT ANTIGLOBULIN TEST (Coombs) — immune vs not; G6PD assay, osmotic fragility/EMA (spherocytosis), haemoglobinopathy screen; identify drug/mechanical cause.

Management

Confirm haemolysis (retics/LDH/bilirubin/haptoglobin) + DAT → treat the cause (steroids for warm AIHA)

1Confirm haemolysis (reticulocytes up, LDH/bilirubin up, haptoglobin down) and do the DIRECT ANTIGLOBULIN TEST: positive → immune (warm/cold AIHA); negative → hereditary (spherocytosis, G6PD) or mechanical/microangiopathic.Gate: Schistocytes + thrombocytopenia = microangiopathic haemolysis (TTP/HUS/DIC) — a haematological emergency; TTP needs PLASMA EXCHANGE and platelets are CONTRAINDICATED.
2Warm AIHA → corticosteroids (± rituximab/splenectomy); G6PD → avoid oxidants; hereditary spherocytosis → folate ± splenectomy (vaccinate + penicillin prophylaxis); treat the underlying trigger.

Treat/remove the cause + folate support — stop the offending drug/oxidant (G6PD), treat infection (cold AIHA from mycoplasma/EBV)

Warm autoimmune haemolysis: corticosteroids (± rituximab) — first-line; transfuse if severe; splenectomy for refractory disease

Hereditary spherocytosis: folate; splenectomy for severe cases — vaccinate + penicillin prophylaxis before/after splenectomy

TTP: PLASMA EXCHANGE (haematological emergency) — do NOT transfuse platelets in TTP — worsens microthrombi

Key points

Anaemia + jaundice + splenomegaly + reticulocytosis + raised LDH/bilirubin + low haptoglobin = haemolysis. DAT splits it: POSITIVE = immune (warm IgG → steroids; cold IgM → mycoplasma/EBV); NEGATIVE = hereditary (spherocytosis, G6PD bite cells/Heinz bodies) or microangiopathic. Schistocytes + low platelets = TTP/HUS → plasma exchange, NO platelets in TTP.

Monitor & prognosis

Hb/reticulocytes/LDH, DAT, response to steroids; splenectomy prophylaxis.

Depends on the cause; warm AIHA often steroid-responsive; TTP fatal untreated but responds to plasma exchange.

Source: BSH; cross-ref child_health (G6PD/spherocytosis/sickle)