INTRAVENOUS IRON SUPPLEMENTATION EFFECT ON TISSUE IRON AND HEMOPROTEINS IN CHRONICALLY PHLEBOTOMIZED LAMBS

Chronic phlebotomy is an important mechanism of iron loss in premature infants. We studied inter-and intraorgan iron allocation in 10 twin l amb pairs undergoing an acute 40-50% reduction in red cell volume foll owed by smaller intermittent phlebotomies over an Ii-day period. One t win received no supplemental iron sucrose, while the other received an average daily intravenous dose of iron sucrose of either 1 (n = 3), 2 (n = 3), 5 (n = 3), or 15 (n = 1) mg.kg(-1).day(-1). The total iron c ontent of the red blood cells, Liver, skeletal muscle, heart, and brai n was directly related to iron dose up to 2 mg.kg(-1).day(-1). Tissue iron concentrations remained stable until Liver iron was <200 gig dry wt, after which iron was preferentially directed to red blood cells ov er skeletal muscle, heart, and brain. Hemoprotein concentrations decre ased proportionately to tissue iron, except myocardial cytochrome c, w hich remained preserved. Any available iron in phlebotomized, rapidly growing lambs is preferentially directed to red blood cells, and lambs require iron supplementation to maintain tissue iron and hemoprotein concentrations. A decrease in nonheme tissue iron results in the high prioritization of iron among iron-containing proteins.