  Quantum electrodynamic (QED) effects that shift the binding energies of
hydrogenic energy levels have been expressed in terms of a semi-analytic
expansion in powers of Zalpha and ln[(Zalpha)^{-2}], where Z is the nuclear
charge number and alpha is the fine-structure constant. For many QED effects,
numerical data are available in the domain of high Z where the Zalpha expansion
fails. In this Letter, we demonstrate that it is possible, within certain
limits of accuracy, to extrapolate the Zalpha-expansion from the low-Z to the
high-Z domain. We also review two-loop self-energy effects and provide an
estimate for the problematic nonlogarithmic coefficient B_60.
