Hereditary spherocytosis natural history, complications and prognosis
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- Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
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Overview
Natural History
- Disease severity and age of presentation — HS can present at any age and with any severity, with case reports describing a range of presentations, from hydrops fetalis in utero through diagnosis in the ninth decade of life [62,65,77-79].
- The majority of affected individuals have mild or moderate hemolysis or hemolytic anemia and a known family history, making diagnosis and treatment relatively straightforward [63]. Individuals with significant severe hemolysis may develop additional complications such as jaundice/hyperbilirubinemia, folate deficiency, or splenomegaly.
Hemolytic anemia — A classification for HS has been developed based on the severity of anemia and markers of hemolysis (reticulocyte count and bilirubin) [63,80]; it characterizes patients as having one of the following:
●HS trait – Normal hemoglobin and reticulocyte count
●Mild HS (20 to 30 percent of cases) – Hemoglobin 11 to 15 g/dL; reticulocytes 3 to 6 percent; bilirubin 17 to 34 micromol/L
●Moderate HS (60 to 75 percent of cases) – Hemoglobin 8 to 12 g/dL; reticulocytes >6 percent; bilirubin >34 micromol/L
●Severe HS (5 percent of cases) – Hemoglobin 6 to 8 g/dL; reticulocytes >10 percent; bilirubin >51 micromol/L
- Neonates may have a relatively normal hemoglobin level at birth that is followed by development of severe anemia, especially during the first three weeks and, in some cases, the first year of life, when the erythropoietic response may not be adequate [81,82]. According to one review, more than half of neonates with HS are not anemic during the first week of life [83]. However, anemia can develop after several days, and is most likely to be severe during the second or third week of life. Some infants require chronic transfusions during the first year; however, transfusion dependence beyond the first year of life is unusual. Red blood cell (RBC) indices are described below. (See 'Initial testing' below.)
- In older children and adults, the presentation may be that of an incidental finding of hemolysis, hemolytic anemia, or spherocytes on the blood smear (picture 2), or the individual may be symptomatic from anemia, splenomegaly, pigment gallstones, or jaundice. Jaundice due to severe hemolysis is less common after the newborn period. (See 'Older children and adults' below.)
- In some cases, co-inheritance of another disorder affecting RBC survival such as sickle cell disease or thalassemia can influence the severity of anemia and make diagnosis more challenging [80]. (See 'Evaluation' below.)
Complications
Exacerbations of anemia in certain settings:
●Infections that impair RBC production in the bone marrow and thus diminish the capacity to compensate for chronic hemolysis may lead to a period of aplasia. A commonly cited cause of transient aplastic crisis is parvovirus B19 infection; other viral or bacterial infections may also cause transient aplasia. This is because individuals with chronic hemolysis are highly dependent on the accelerated production of new RBCs by the bone marrow, and they can experience a rapid drop in hemoglobin level when the bone marrow is unable to compensate for hemolysis. If an individual with HS develops a precipitous decline in hemoglobin level or reticulocyte count, testing for parvovirus infection is appropriate.
●Conditions that increase the size of the spleen, such as infectious mononucleosis, may cause increased splenic pooling of RBCs and/or increased hemolysis.
●Individuals who develop folate, vitamin B12, or iron deficiency may be unable to produce sufficient RBCs to compensate for those lost by hemolysis.
●Anemia may worsen during pregnancy, as the RBC mass and plasma volume expand to meet the physiologic needs of the pregnancy. Attention to folic acid supplantation and iron stores are also important so as not to impair RBC production.
●Individuals who experience a decline from their baseline hemoglobin level and/or reduction in baseline reticulocyte count are likely to require more frequent monitoring and/or additional testing, details of which will depend on the associated symptoms and laboratory findings.
Complications of hemolysis — Common complications of hemolysis include neonatal jaundice, splenomegaly, and pigment gallstones.
●Rarely, hemolysis may be severe enough to cause extramedullary hematopoiesis and/or growth delay [84,85]. A small subset of these children may be at risk for iron overload due to increased iron absorption and/or transfusions, although the majority of patients with HS do not develop iron overload [62].
●Other rare complications that have been reported include leg ulcers, priapism, neuromuscular disorders, cardiac disease, and gout; in some cases, these may represent coincidental rather than causal associations [62,86,87].
Neonatal jaundice — HS may present in the neonatal period with jaundice and hyperbilirubinemia, and the serum bilirubin level may not peak until several days after birth. Some experts have proposed that HS is underdiagnosed as a cause of neonatal jaundice [88]. A requirement for phototherapy and/or exchange transfusion during this period is common [62,81]. (See 'Neonates' below.)
Hyperbilirubinemia may be exacerbated by concomitant Gilbert syndrome. (See "Pathogenesis and etiology of unconjugated hyperbilirubinemia in the newborn".)
Splenomegaly — Splenomegaly is rare in neonates, but can often be seen in older children and adults with HS [83]. Early reports of family studies found palpable spleens in over three-fourths of affected members, but this may reflect a skewed population with the most severe disease. In these studies, the relationship between disease severity and splenic size was not linear [89].
There is no evidence of an increased risk of splenic rupture.
Indications for splenectomy in HS and possible complications are discussed below. (See 'Splenectomy' below.)
Pigment gallstones — Pigment (bilirubin) gallstones are common in individuals with HS and may be the presenting finding in adults. Gallstones are unlikely before the age of 10 years but are seen in as many as half of adults, especially those with more severe hemolysis [90]. Gallstones appear to be more common in individuals with Gilbert syndrome.[1]
Obstructive jaundice or cholecystitis is treated similarly to that in individuals without HS. If cholecystectomy is performed, it may be worthwhile to discuss whether splenectomy was also planned, as the procedures could be combined; however, splenectomy should not be routinely performed during cholecystectomy [92]
Prognosis
References
- ↑ del Giudice EM, Perrotta S, Nobili B, Specchia C, d'Urzo G, Iolascon A (1999). "Coinheritance of Gilbert syndrome increases the risk for developing gallstones in patients with hereditary spherocytosis". Blood. 94 (7): 2259–62. PMID 10498597.