Elliptocytosis, Hereditary Workup
- Author: Daniel J Kim, MD; Chief Editor: Emmanuel C Besa, MD more...
Laboratory Studies
- Microscopic examination of peripheral smears reveals that about 25% (sometimes nearly 100%) of cells are characteristically elliptical and often described as cigar-shaped. Some cases have fewer than 25% elliptocytes. Fragmented cells may also be seen.
- Elliptocytes can occur in many other conditions (eg, iron deficiency, leukemias, megaloblastic anemias, myeloproliferative diseases, myelodysplastic syndromes) but usually do not reach the proportions observed in patients with hereditary elliptocytosis (HE). Elliptocytes in patients with severe iron deficient anemia are markedly hypochromic, a finding not associated with any of the HE disorders. Of most importance, patients with HE have a positive family history, whereas patients with other diseases associated with elliptocytes have underlying manifestations of their particular diseases.
- Patients with HPP have an increased number of microspherocytes, whereas patients with stomatocytic elliptocytosis have distinctive, rounded elliptocytes bisected by a bar of hemoglobin, as described previously.
- Pseudoelliptocytosis is a common artifact of peripheral smear preparation, in which the blood cells appear stretched and lined up in parallel; this finding is in contrast to true elliptocytosis in which the cells are oriented in different directions.
- Laboratory studies may show evidence of hemolysis, such as low haptoglobin levels; a high reticulocyte count; and elevated concentrations of lactic dehydrogenase (LDH), indirect bilirubin, and urinary bilinogen. It is important to emphasize that the percentage of elliptocytes observed is not correlated to the severity of hemolysis.
- Results of osmotic fragility test are within reference ranges in typical HE, but values are increased in spherocytic HE and HPP.
- When tested for thermal stability, normal RBCs can withstand temperatures up to 49°C, but RBCs associated with HPP denature at 45-46°C.
- If necessary, specialized laboratories can identify the underlying skeletal defects by quantifying membrane proteins, studying spectrin function, and performing molecular studies. Only rarely are such studies indicated.
Imaging Studies
- Imaging studies are not needed in the diagnosis of HE, but can reveal findings consistent with chronic hemolysis, such as splenomegaly and gallstones.
Histologic Findings
Elliptocytes are observed on peripheral blood smears.
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