The altitude of the device does not have a lot of relationship to the latitude and longitude.
For example, a device aloft in an airplane will have a higher altitude than will a device at ground level over the same latitude and longitude. Locations retrieved by LocationManager
that used GPS to get the location fix may have altitude information, but that will be the altitude of the device.
If you want the elevation of ground level at a particular latitude and longitude, you would need to look that up in some sort of GIS database. Android does not ship with one of these, and so you will need to use a search engine to find a suitable database for you use.