<prompt> Earliest manifestation of megaloblastic anemia isMacrocytosisHypersegmented neutrophilsBasophilic stipplingCabot ring  <response>: Ref: Harrison 18e p866, 17e p645-646, Tejinder Singh 2e p54-61 Peripheral blood pictureBone marrow pictureMacrocytosis MCV, MCH. Normal MCHCPeripheral smear Macroovalocytes Few nucleated RBCs Evidence of dyserythropoiesis like-Basophilic stipplingCabot ringHowell- Jolly bodies Hb HematocritReticulocyte count Normal or mild decreaseWhite cells- LeucopeniaHypersegmented neutrophils Macropolycytes- First manifestation PlateletsPancytopenia 10-20 Lab investigations:Serum iron, ferritin - in pure VitB12 Folate defectSerum bilirubin LDH - due to hemolytic componentSchillings test: Used to assess status of intrinsic factor IF Vit B12 to distinguish pernicious anemia from other causes of Vit.B12 deficiency.Moderate- marked hypercellularityErythroid hyperplasiaM:E ratio reversalErthropoiesis- MegaloblasticGiant metamyelocytesMildly reduced megakaryocytesBM iron moderately increased in pure Vit B12 Folate defects. 