  We analyze the constraints on neutrino mass spectra with extra sterile
neutrinos as implied by the LSND experiment. The various mass related
observables in neutrinoless double beta decay, tritium beta decay and cosmology
are discussed. Both neutrino oscillation results as well as recent cosmological
neutrino mass bounds are taken into account. We find that some of the allowed
mass patterns are severely restricted by the current constraints, in particular
by the cosmological constraints on the total sum of neutrino masses and by the
non-maximality of the solar neutrino mixing angle. Furthermore, we estimate the
form of the four neutrino mass matrices and also comment on the situation in
scenarios with two additional sterile neutrinos.
