  We construct approximate formulas for the O(\alpha_s^3) QCD contributions to
vector, axial-vector, scalar and pseudo-scalar quark current correlators, which
are valid for arbitrary values of momenta and masses. The derivation is based
on conformal mapping and the Pade approximation procedure and incorporates
known expansions in the low energy, threshold and high energy regions. We use
our results to estimate additional terms in these expansions.
