Hereditary spherocytosis is characterized by a
membrane defect within red blood cells resulting in a shortened survival
time. The red cells have low amounts of lipid within the bilayer membrane
that lead to an abnormally small amount of surface area. Because the red
blood cells are spherocytic, flow through the spleen is difficult, resulting
in hemolysis. It is caused by an inherited metabolic defect.
Congenital Spherocytic Anemia; Minkowski-Chauffard
Hemolytic anemia caused by red blood cell membrane defect.
Although a spectrin deficiency is seen in most hereditary spherocytosis
patients, the principal defect is an abnormality of the RBC membrane protein
1:5000 in the general population; mainly in white
populations originating from areas around the Mediterranean sea.
Autosomal dominant in most cases, but
autosomal recessive forms exist (spectrin deficiency). Four subsets can be
defined by the protein defect: (1) partial spectrin deficiency (mutations of
alpha-spectrin are associated with recessive forms, whereas mutations of
beta-spectrin produce autosomal dominant forms); (2) combined partial
spectrin/ankyrin deficiency; (3) partial band 3 protein deficiency; and (4)
protein 4.2 deficiency.
The protein abnormality causes defects in
vertical stabilization of the phospholipid bilayer of the red cell membrane,
which causes a separation of the spectrin-phospholipid bilayer. As a
consequence, portions of the phospholipid bilayer form vesicles and thus are
lost from the red blood cell (RBC) surface—the surface area is decreased
and spherocytes are formed. These abnormal RBCs are retained in the spleen
and destroyed, leading to anemia.
Based on clinical signs of anemia, analysis of the
peripheral smear (numerous spherocytes), moderate anemia with reticulocyte
count greater than 10%, and osmotic fragility test (which reflects the
decreased surface-to-volume ratio of red blood cells). Erythrocytes also
have increased autohemolysis, increased metabolic depletion of glucose, and
increased mechanical fragility.
Symptoms can be quite variable. The
erythrocytic fragility and hepatic enzyme immaturity may cause significant
neonatal jaundice. Whether or not occasional acute aplastic crises
(especially after parvovirus infection) is revealing; the clinical picture
is mainly that of an anemia that may vary from mild to severe.
Hyperbilirubinemia, predisposing to cholelithiasis, elevated plasma lactate
dehydrogenase, splenomegaly, endocrine dysfunctions, and acute renal failure
following hemolytic crisis, is not unusual. Splenectomy markedly improves
Obtain a complete cell blood
count (CBC) and coagulation profile. In case of severe anemia, elective
surgical procedures should be delayed until hemoglobin level has been
corrected. For surgical procedures with the potential for large blood loss
and fluid shift, preoperative blood cross-match must be obtained.
Oxygen-carrying capacity is the most
important consideration associated with this medical condition. It is
essential to prevent red cell hemolysis often caused by hyperdynamic
cardiovascular responses. The prevention of hypothermia is also important to
limit venous stasis, red cells fragility, and hemolysis. Glucose intravenous
solutions must be administered to maintain red cells energy across the
membrane and limit the possibility of spherocytosis.