  We apply the low-energy theorems to analyze the recent lattice QCD results
for the two-nucleon system at a pion mass of $M_\pi\simeq 450$ MeV obtained by
the NPLQCD collaboration. We find that the binding energies of the deuteron and
dineutron are inconsistent with the low-energy behavior of the corresponding
phase shifts within the quoted uncertainties and vice versa. Using the binding
energies of the deuteron and dineutron as input, we employ the low-energy
theorems to predict the phase shifts and extract the scattering length and the
effective range in the $^3S_1$ and $^1S_0$ channels. Our results for these
quantities are consistent with those obtained by the NPLQCD collaboration from
effective field theory analyses but are in conflict with their determination
based on the effective-range approximation.
