On page 132 of PostGIS in Action, Second Edition it says,
QGIS SPIT QGIS comes packaged with a tool called SPIT that allows you to batch-load Esri shapefiles into a PostgreSQL database, bypassing rendering. One crippling annoyance with this tool is its automatic conversion of all field names to uppercase. In PostgreSQL, uppercase field names must be double-quoted in queries, and that’s a lot of extra typing of quotes. If you’re going to use SPIT, we suggest that you create a function to convert everything back to lowercase after import.