Heme Synthesis Flashcards
what does normal hemoglobin production depend upon (3 major aspects)
- adequate iron, both delivery and supply
- adequate protoporphyrin synthesis
- adequate globin synthesis
where does protoporphyrin synthesis begin
mitochondria
What carries iron, and in what state of iron (2+ or 3+), to the RBC precursor? what happens to the iron in the cell?
the transport protein, transferrin, as ferric (think 3+ is icky, Us 2 is good); most of it goes to the mitochondria where it is reduced to the ferrous, 2+ state
what porphyrins are of clinical significance?
uroporphyrin, coproporphyrin, and protoporphyrin
overproduction or accumulation of porphyrins and/or precursors causes ?
porphyrias, of varied types;
such as: acute intermittent, porphyria variegata, porphyria cutanea tarda, erythropoeitic protoporphyria
Where can porphyrins accumulate?
bone marrow (erythropoietic) and liver (hepatic)
What types of porphyrias can cause neuropsychiatric symptoms (give what accumulates and symptoms)
those of early precursors such as ALA and porphobilinogen; abdominal pain, vomiting, constipation, tachycardia, HTN, psychiatrics symps
WHat can excess of later porphyrin intermediates (name them) cause?
uro- copro- and proto-porphyrins; cutaneous porphyrias, incl photosensitivity, blisters, hyperpigmentation
what type of urine specimen is needed to measure ALA, PBG, uroporphyrin, and coproporphyrins, and give storage and pH requirements
a 24 hour specimen, refrigerated and in brown bottle; bc ALA is better preserved in acid conditions and PBG in alkaline, bicarb is used to compromise and keep pH around 7
protoporphyrin IX combines with what to yield heme?
ferrous iron
describe normal adult hemoglobin and the most common types
tetramers of two alpha and two non-alpha globin chains;
up to 97% are a2B2 (this is HbA)
2 to 3% are HbA2, with a2d2 (delta instead of beta)
1 to 25 HbF, with gamma instead of beta, plus alpha
