  We present an extension of chiral perturbation theory that explicitly
includes an isosinglet scalar in the Lagrangian. The dynamical effects from the
scalar state is of phenomenological relevance in theories where the mass of the
isosinglet scalar is comparable to the mass of the pseudo-Goldstone bosons.
This near-degeneracy of states is for example observed in certain
near-conformal BSM models. From the Lagrangian we calculate the one-loop
radiative corrections to the pion mass, the pion decay constant, and the scalar
mass. We then proceed and use the results to fit numerical lattice data for an
SU(3) gauge theory with $N_f=8$ light flavours in the fundamental
representation.
