High-altitude exposure is associated with an increase in skeletal muscle ferroportin mRNA levels. The changes in ferroportin mRNA levels in muscle biopsies obtained from vastus lateralis under normoxic conditions at SL and during exposure to HA (4559 m) for 7 to 9 days are shown. The target mRNA content is normalized to total cDNA content and expressed relative to the value at SL, which was arbitrarily defined as 100. The values are means ± SE for 9 participants. The calculation of statistical differences from normoxia was performed using the Wilcoxon test. +P = .05.