Hematology & Clinical Biochemistry & Family Medicine

Sphérocytes | Clinique Omicron Québec

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Spherocytes are erythrocytes with an abnormal morphology, showing on the stained blood smear a homogeneous spherical shape + a more intense color (relative hyperchromia - increased CHCM) + and the absence of the clear central zone (pallor) characteristic of normal biconcave erythrocytes. This morphology results from a reduction in the ratio of membrane surface area to cell volume: spherocytes have a normal or slightly reduced volume but a reduced membrane surface area - they are therefore less deformable than normal erythrocytes + unable to compress to pass through the narrow capillary slits of the splenic red pulp + and destroyed prematurely by splenic macrophages (extravascular hemolysis) leading to hemolytic anemia. Erythrocyte spherization results from two distinct pathophysiological mechanisms requiring a different diagnostic approach: hereditary spherocytosis - in which genetic mutations (mostly autosomal dominant) affect the proteins of the erythrocyte cytoskeleton (spectrin + ankyrin + band 3 protein + 4.2 protein + 4 protein.1) → destabilization of the lipid bilayer-cytoskeleton bond → progressive loss of membrane fragments (vesiculation) → reduced surface/volume ratio → progressive spherization of the RBC on repeated passage through the spleen → intra-splenic hemolysis → NEGATIVE Coombs test - and autoimmune hemolytic anemia (AHAI) - in which anti-erythrocyte autoantibodies (predominantly warm IgG) opsonize RBCs → splenic macrophages partially remove the IgG-covered membrane (partial phagocytosis) → reduction of membrane surface → spherization → extravascular hemolysis → POSITIVE Coombs test. The distinction between AHAI and hereditary spherocytosis is therefore essentially based on the direct Coombs test - the central examination in the evaluation of any patient with spherocytes on the smear.

Morphology and identification on smears

Characteristic aspect round + dense + hyperchromic cells + without a central pale zone + diameter slightly smaller than normal RBCs + regular and smooth contour (unlike irregular acanthocytes) + MCHC is elevated (≥ 36 g/dL) in hereditary spherocytosis
Diagnostic threshold 5 % spherocytes on the smear = significant + in severe hereditary spherocytosis: 15–40 % spherocytes + in AIHA: variable + a few percent to numerous spherocytes + in very mild forms: few spherocytes and difficult to identify
Associations on the NFS: Normocytic or slightly macrocytic anemia (reticulocytosis) + reticulocytosis (regenerative hemolysis) + elevated LDH (cell destruction) + low haptoglobin (free hemoglobin uptake) + elevated indirect bilirubin (hemolytic jaundice)

Causes of Spherocytes - Differential Diagnosis

Cause	Mechanism	Coombs direct	Key Diagnostic Elements
Hereditary spherocytosis (HS)	Erythrocytic cytoskeleton mutations (spectrin + ankyrin + band 3 + protein 4.2) → membrane blebbing → reduced surface area/volume	NEGATIVE	Family history (AD in 75% %+ de novo 25% %) + splenomegaly + neonatal jaundice + pigmentary gallstones + increased osmotic fragility + EMA binding test (ektacytometry) + genotyping if atypical form
Warm antibody (IgG)	Auto-antibodies IgG anti-GR -> opsonization -> partial phagocytosis by splenic macrophages -> spherocytosis	POSITIVE (IgG + IgG+C3)	Coombs IgG positive +++ + splenomegaly + jaundice + underlying cause (CLL + lymphoma + lupus + medications - methyldopa + penicillin + idiopathic AIHA)
AHAI with cold agglutinins (IgM)	IgM anti-I/i → cold complement fixation → C3b on RBCs → hepatic destruction (reticuloendothelial system)	POSITIVE (anti-C3d)	Cold acrocyanosis + high cold agglutinin titer + positive Coombs C3 (negative IgG) + causes: mycoplasma + EBV + lymphoma
Transfusion reaction hemolytic	Alloantibodies against donor RBCs → hemolysis → spherocytosis of transfused opsonized RBCs	POSITIVE (alloantibody)	Recent transfusion + drop in hemoglobin + positive direct Coombs + hemoglobinuria + fever
Drug-induced hemolytic anemias	Drug → hapten on RBCs + allo-antibodies → hemolysis + positive Coombs	Variable (often POSITIVE)	Introduction of a new drug (methyldopa + high-dose penicillin + rifampicin + quinine + cephalosporins)
Extensive burns	Direct heat → denaturation of membrane proteins → spherization + thermal hemolysis	NEGATIVE	Obvious context of severe burns + spherocytes + possible schistocytes

Hereditary Spherocytosis - details

Genetics autosomal dominant transmission in 75 %of cases (one affected parent) + de novo in 25 % + ANK1 (ankyrin — 40–50 % ) + SPTA1 (alpha-spectrin) + SPTB (beta-spectrin) + SLC4A1 (band 3) + EPB42 (protein 4.2) + highly variable severity depending on the mutation + the same family can have members with mild and severe forms
Clinical Presentation: classic triad anemia + jaundice + splenomegaly + neonatal jaundice in 50% (%) (acute hemolysis at birth) + early pigment gallstones (calcium bilirubinate stones) (40% (%) before age 30) -> prophylactic cholecystectomy discussed + aplastic crises (parvovirus B19 -> inhibition of erythropoiesis -> sudden drop in Hb -> urgent transfusion) + hemolytic crises (infections -> accelerated hemolysis)
Diagnostic tests: Osmotic fragility test (increased osmotic fragility — lysis at higher than normal NaCl concentrations) + EMA binding test (erythrocyte membrane antigen — reduced fluorescence by flow cytometry = better non-invasive test — sensitivity 93 %+ specificity 99 % ) + ektacytometry (LORCA — measures deformability as a function of osmolality) + genotyping if tests are inconclusive
Processing : Folic acid 5 mg/day (to compensate for chronic hemolysis) + splenectomy after 5-6 years → normalization of Hb + correction of jaundice + but persistence of spherocytes on the smear (morphology does not change - it is splenic destruction that is suppressed) + meningococcal vaccination + pneumococcal vaccination + Hib vaccination BEFORE splenectomy + transfusion if severe aplastic crisis (Hb < 60–70 g/L

AHAI to warm antibodies - treatment

Prednisone 1–1,5 mg/kg/jour en première ligne → réponse dans 70–80 % des cas en 1–3 semaines + décroissance progressive sur 3–6 mois
Rituximab (anti-CD20): 375 mg/m² IV for 4 weeks → if insufficient corticosteroids + or severe forms + or relapses
Splenectomy if relapses multiple + or cortico-dependence → efficacy 60-70 % long-term + mandatory vaccination before
Treatment of the underlying cause LLC + lymphoma + lupus + stop responsible medication

ℙ️ The direct Coombs test (direct antiglobulin test - DAT) is the key examination to guide the diagnosis of spherocytes: positive → AIHA (IgG or C3) or alloimmune hemolysis → immunosuppressive treatment + negative → hereditary spherocytosis → EMA binding test or osmotic fragility test + negative can also suggest burns or rarely mild forms of AIHA (false-negative Coombs if low IgG load). Therapeutic decision fundamentally differs depending on the positivity or negativity of the Coombs test.

Medical consultation recommended

Consult a doctor if hemolytic anemia is suspected in a patient with jaundice + pallor + splenomegaly + or if spherocytes are reported on a blood smear — a direct Coombs test + LDH + haptoglobin + indirect bilirubin + reticulocyte count should be performed to differentiate between hereditary spherocytosis and AIHA and guide management. Consult the emergency room if severe anemia (Hb < 70 g/L) + respiratory distress + or resting tachycardia appear during a hemolytic or aplastic crisis. For the workup of hemolytic anemia with spherocytes, Clinique Omicron offers medical consultations at its service points in Quebec and via telemedicine. To make an appointment, visit cliniqueomicron.ca.

Consult at Clinique Omicron

Clinique Omicron's physician associates and nurse practitioners (NPs) prescribe and interpret blood smears with spherocyte identification, perform complete hemolysis workups (Coombs + LDH + haptoglobin + bilirubin + reticulocytes), differentiate hereditary spherocytosis from AIHA based on direct Coombs, initiate prednisone for confirmed AIHA, prescribe folic acid for hereditary spherocytosis, refer severe cases and decisions for splenectomy or rituximab to hematology, and ensure pre-splenectomy vaccination. Consultations are available at several service points in Quebec and via telemedicine. To book an appointment, visit cliniqueomicron.ca.

The content of this page is for informational purposes only and does not replace the advice of a doctor or hematologist. The distinction between hereditary spherocytosis and AIHA relies on the direct Coombs test — immunosuppressive therapy (prednisone) erroneously initiated in hereditary spherocytosis is useless and potentially harmful.

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