Power headroom reports may be transmitted from a wireless terminal to a base station wherein a primary component carrier and at least one secondary component carrier are provided for uplink transmissions from the wireless terminal to the base station and wherein a respective component carrier index is assigned to each of the at least one secondary component carriers provided for the wireless terminal. Respective power headroom reports may be generated for the primary component carrier and for each of the at least one secondary component carriers, and a MAC control element may be generated including the power headroom reports for the primary and secondary component carriers. More particularly, the power headroom reports for each of the at least one secondary component carriers may be arranged in order of the component carrier indices for the respective secondary component carriers. The MAC control element including the power headroom reports for the primary and secondary component carriers may be transmitted from the wireless terminal to the base station over one of the component carriers. Related wireless terminals, and base stations are also discussed.