In the heat test unstable hemoglobins precipitate more readily than most Hgbs. Unstable hemoglobins include Hgb E , Hgb Koln and certain fast migrating hemoglobins . Hgb F is normal by heat testing. Heinz bodies are visible as faint blue blushes in the RBCs. A recticulocyte is seen at lower left.
Homozygous forms are usually incompatible with life.
Low O 2 affinity hemoglobins readily release O 2 to tissue, but are poorly saturated, producing a right shift of the O 2 -dissociation curve. Erythropoietin decreases as O 2 tissue levels increase, causing a mild anemia. Low O 2 saturation may result in cyanosis. 2 at high O 2 tension and release it at low O 2 tension. With deoxygenation the alpha-beta interface tightens lessening the affinity of Hgb for oxygen.