ssP.R. JayawickramaD.S. KaluwadugeK.K.G. KandewaththaM. KanchanamalaUNIVERSITY of RUHUNA , FACULTY of MEDICINE.23.11.20121
A four years old boy was brought to the pediatrichospital with a history of severe back pain anduncontrolled vomiting since previous night. FurtherHis mother told that her child was complainingabout some attacks of back pain occurring duringthe past months.On examination patient was pale and spleen waspalpable below the costal margin……!!!!2
In investigation,• Haemoglobin level - decreased• Peripheral blood smear - sickled cells- nucleated RBC-features of microcytichypochromic anaemia• X-ray of the skull – hair on end appearance offrontal bone3
SICKLE CELL ANAEMIA……????Inherited.form of an anaemia as a result of mutation in Hb.RBC sickled or crescent shaped.NOT enough healthy RBC to carry adequateoxygen.4
Normally, humans haveOf these, Haemoglobin A makes up around 96-97%of the normal haemoglobin in humans.HaemoglobinA two alpha two betaA2 two alpha two deltaF two alpha two gamma5
Common types of Sickle CellDisordersType ofanaemiaHemoglobinvariationcommentSickle CellAnemiaSicklehaemoglobin(HbS) + SicklehaemoglobinMost Severe –No HbAHemoglobin S-Beta thalassemiaSicklehaemoglobin(HbS) + reducedHbAMild form ofSickle CellDisorderHemoglobin S-C Sickle Mild form of 6
PathophysiologyIs caused by• point mutation in the β-globin chain of Hbglutamic (hydrophobic amino acid)valine( hydrophilic )• at the 6th positionLife span• RBC 90–120 days• sickle cells 10–20 days.
• exposure to P O2 < 40 mmHg for 2 to 4 minutes• polymerization of Hb• The initiation of polymerization may be-incomplete and-reversible , if re-oxygenation occurs early inthe process.• Repetitive exposure to alternating de-oxygenated and oxygenated states lead to-membrane distortion,-irreversible sickling.