Dear Zarak, a good blood smear can go a long way in the diagnosis when correctly examined and reported.

Dear Dr Muhammad

Spherocytic RBCs are not specific to Hereditary spherocytosis. Autoimmune hemolytic anemia also may produce spherocytosis, but this disorder usually can be excluded by negative findings on a direct antiglobulin test.

The most sensitive test for HS is the incubated osmotic fragility test

The blood film will be a good indicator but the diagnosis can be confirmed by osmotic fragility testing.

I guess as this is a genetic disorder it could theoretically be confirmed by genetic analysis but i am not sure if this is possible.

Linda’s Hoyland

Which test ??

Spherocytes are non specific. But family history and excluding other causes usually will point to diagnosis.

Hi Muhammad and others colleagues,

As Linda said, Osmotic fragility test may be helpful in the clinical investigation of patients with spherocytes in peripheral blood. This test is based on the fragility of erythrocytes when exposed in graded hypotonic solutions (e.g. NaCl solutions). The following references may be helpful: https://www.ncbi.nlm.nih.gov/books/NBK190583/ and http://www.ithanet.eu/ithapedia/index.php/Protocol:Osmotic_fragility_test. Important to note that these test is positive in patients with high fragility, not only hereditary spherocytosis but distinguish patients with others causes of spherocytosis, such as autoimmune conditions

As a heterogeneous genetic disease, is complicated determine the locus involved in disease, but a SDS-PAGE of proteins from erythrocyte membrane can indicate the vertical defects commonly observed, which include Ankyrin, B-spectrin and Band 3.

Best regards.

Juan.

Tests for spherocytosis ; Osmotic fragility test, Direct antiglobuln test and Autohemolysis test

In UK, if there is a family history and diagnostic blood film, no other test is deemed necessary. if there is no family history & clinical diagnosis of HS seems likely, we do EMA dye binding test for confirmation of diagnosis in addition to FBC & film

Guidelines

Article Guidelines for the diagnosis and management of hereditary sp...

Hereditary spherocytosis can be suspected first by an increasing of MCHC (>370g/L) which indicates an alteration of the volume/surface ratio in the RBC. This artifact is described as "hyperchromia" although these RBC did not have a "true" increasing of their hemoglobin concentration. Besides, some hematological analyzers that use for RBC the iso-volumetric change of shape (spherized) (Siemens Advia; Abbott Sapphire) provide most evocative cytograms, almost "diagnostic". [Kutter D, Coulon N, Stirn F, Thoma M, Janecki J. Demonstration and quantification of "hyperchromic" erythrocytes by haematological analysers. Application to screening for hereditary and acquired spherocytosis. Clin Lab. 2002;48(3-4):163-70.]

The subsequent microscopic observation of a PB smear can allow differentiating the morphology of spherocytes from others causes of increased MCHC, cold agglutination in primis. Familiar involvement and the increased osmotic fragility may suffice to affirm the diagnosis. Confirmatory genetic tests if available can also be used.

Most of the aspects are well covered in the above answers. History of the patient is the starting point. A disease from early childhood having anemia, hemolytic jauncice, splenomegaly... all increasing as crisis with precipitating cause like infections will be very important. 80% of cases present as autosomal dominant character. So complete family examination will be the most helpful.

Spherocytes in the blood smear are varying in number and so osmotic fragility curve distortion (at 5 to 5.5 g/l NaCl) trail will dpend on it. Further along with reticulocytosis, HS spherocytes look smaller in diameter, unlike AIHA spherocytes. If only smear is given without any other history or findings, very typical HS spherocytes should not be missed, but in absence of advanced lab tests available, as it is there in developing countries, I, after looking at the smear will definitely do retic count and spin the blood tube to look at the plasma for icterus, before asking for family history and study.

The clinical history and medical antecedents are very important

Apart from the above excellent comments made, I would stress that when one has to deal with the common form of autosomal dominant (AD) HS, that has been genetically linked to defects of the ankyrin gene, measurement of RBC spectrin and ankyrin by radioimmunoassay (RIA) indicates a significant reduction of both in the erythrocytes of patients and family kindreds. Most patients with dominant HS have combined ankyrin and spectrin deficiency and that the two proteins are usually about equally deficient, suggesting that defects in ankyrin expression, ankyrin stability, or ankyrin band 3 (AE1) interactions may be common in AD HS (Savvides et al, Blood 82: 2953-60, 1993).

I agree with Christos answer regarding the role of both Ankrin and Spectrin deficiency in the RBC of the HS. The description of different immunoassays methods is also important. However, I think that in answering a question in RG it should be considered the country of origin, wondering if technically sophisticated diagnostic methods are available in those places. I often stick to this rule, limiting myself to suggest only diagnostic strategies hypothetically (or realistically) available to the Colleague who poses the question

Thanks Antonio for expressing the realistic picture we are facng. The details at molecular level is acessible to all either in library or on net, but when a blood smear is being examined, only icterus, anemia, reticulocytosis and family history only have helped us by advising the clinician for splenectomy. The results are wonderful.