HEREDITARY SPHEROCYTOSIS

 INTRODUCTION

HS is one among the foremost common Hemolytic anemias, with a frequency of one in 5000 within the U.S. and one in 2000 in people of northern European ancestry, conjointly seen in southeast Asia, India, and the Kingdom of Nepal.

DEFINITION

Hemolytic Disorder is caused by defective vertical interactions between the lipid bilayer and body structure of the red blood cell membrane, leading to vesication and loss of membrane, red blood cell formation, and lysis (spherocytes are less deformable than a traditional red blood cell, trapped  and destroyed within the spleen.)

INHERITANCE-AD most typical, AR inheritance is seen in few cases.

INCIDENCE - One in 5000 within the U.S.

GENDER, RACE AND AGE DISTRIBUTION - Equal gender incidence , MC in patients of northern European descent (1 in 2000).

CLINICAL FEATURES - TRIAD OF Variably severe hemolytic anemia, jaundice, spleenomegaly. 

typically follows a stable clinical course, however could also be punctuated by

a)APLASTIC CRISIS- triggered by acute parvo infection.

b)HEMOLYTIC  CRISIS – intercurrent events resulting in raised RBC destruction like in glandular fever.

Cholelithiasis happens in 40-50% of patients.

Other presentations- hemolytic disease  of newborn and HS in pregnancy.

CLINICAL CLASSIFICATION based on  SPECTRIN CONTENT

MILD HS:80-100%

MODERATE HS: 50-80%

MODERATELY SEVERE HS: 40-70%

SEVERE HS: 20-50%

PATHOGENESIS:

LIFGHT MICROSCOPY :

PERIPHERAL BLOOD SMEAR-Spherocytes ( dark red  with no central pallor), polychromasia.

INCREASED retic count ( 5-40%).

SPLEEN- engorged splenic  cords, increase in range of splenic macrophages with phagocytosed red cells in them.

BONE MARROW –erythroid hyperplasia with normocytic reaction.

PERIPHERAL BLOOD FILM SHOWING SPHEROCYTES

ANCILLARY STUDIES

The screening tests –

a)OSMOTIC FRAGILITY –spherocytes are osmotically fragile.

b)EOSIN five MALEIMIDE – sensitive screening test –decreased fluorescence is seen in Hereditary Spherocytosis.

Others tests- incubated fragility test, glycerol lysis test, ektacytometry .

Biochemistry –serum bilirubin, urine bilirubin, urine urobilinogen raised.

Serum haptoglobin levels reduced. 

serum LDH levels raised.

Direct coombs test negative.

Definitive diagnosis – distinguishing the defective protein by SDS PAGE  ANALYSIS OR  DNA SEQUENCING.

DIAGNOSIS

DIFFERENTIAL DIAGNOSIS  

COMPLICATIONS

PROGNOSIS AND THERAPY

Supportive care, no specific medical aid.

Severe cases- folic acid supplementation and SPLEENECTOMY.

MORBIDITY AND MORTALITY

Mild morbidity due to complications of chronic hemolysis.

Aplastic crises due to parvo B19

Megaloblastic anemia

Slightly raised mortality, typically a result of post splenectomy infection.