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Anemias
Caused By Excessive Hemolysis
Symptoms
and Signs?
Systemic manifestations
resemble those of other anemias. Hemolysis may be acute, chronic,
or episodic. Hemolytic crisis (acute, severe hemolysis) is
uncommon; it may be accompanied by chills, fever, pain in the back
and abdomen, prostration, and shock. In severe cases, hemolysis
increases (jaundice, splenomegaly, and, in certain types of
hemolysis, hemoglobinuria and hemosiderinuria), and erythropoiesis
increases (reticulocytosis, hyperactive bone marrow). In chronic
hemolysis, anemia may be exacerbated by aplastic crisis (temporary
failure of erythropoiesis); this is usually related to an
infection, often parvovirus.
Laboratory
Findings
Jaundice occurs when the conversion of Hb
to bilirubin exceeds the liver's capacity to form bilirubin glucuronide and
excrete it into bile (see also Ch.
38). Thus, unconjugated (indirect) bilirubin accumulates. Increased
pigment catabolism is also manifested by increased stercobilin in the stool
and urobilinogen in the urine. Pigment gallstones frequently complicate
chronic hemolysis.
Although hemolysis can usually be
identified by the simple criteria described, the definitive criterion is a
measure of RBC survival, preferably with a nonreutilizable label such as
radiochromium (51Cr). The measured survival of radiolabeled RBCs
establishes not only hemolysis but also, with body surface counting, sites of
RBC sequestration, thereby providing diagnostic and therapeutic options. In
general, a half-life (for 51Cr-labeled RBCs) of >= 18 days
(normal, 28 to 32 days) indicates hemolysis mild enough for a normally
responsive marrow to maintain normal RBC values. The term compensated
hemolytic anemia refers to a marrow that responds appropriately,
producing near-normal RBC values. Selective splenic sequestration with
expected repair after splenectomy can be anticipated when surface count ratios
reveal a spleen:liver ratio > 3:1 (normal, 1:1).
Other tests (eg, increased indirect
hyperbilirubinemia, increased fecal urobilinogen or carbon monoxide
production) or evidence of repair (reticulocytosis) supports but does not
establish the likelihood of hemolysis. LDH is commonly increased in hemolysis.
Morphologic examination of the peripheral
blood may show evidence of hemolysis (eg, fragmentation, spherocytes) or
erythrophagocytosis, which helps establish the diagnosis and the mechanism (ie,
intravascular hemolysis). Other tests for causes of hemolysis include Hb
electrophoresis, RBC enzyme assays, osmotic fragility, direct antiglobulin
(Coombs') test, cold agglutinins, and acid hemolysis or sucrose lysis tests
reticulocyte: a young red cell (erythrocyte) released by
the bone marrow that contains no nucleus but has residual RNA;
normally composes about 1% of circulating blood cells. The
reticulocyte count is increased in hemolytic anemia.
Can support there being anemia, but not a
diagnosis in itself
2-butoxyethanol
Other definitions
for those who may need to check your blood in particular ways.
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