Changing the Lost status on the additem.pl page doesn't change the Checkout Status and doesn't charge the patron account with replacement cost. 

Example:

A book was checked out to an irresponsible patron. The irresponsible patron LOST it. It was marked lost from using the 1 - Lost status on the Edit Items page
cataloguing/additem.pl

After changing the status, the item is still checked out to the irresponsible patron, and her account has not been charged replacement cost, even though the item shows lost in the catalogue/detail.pl.

In contrast:

Believe it or not, the patron also lost another item. This item was marked lost from the Item Detail page
catalogue/moredetail.pl

This action changed the Checkout Status to Not Checked out and charged
the patron account the replacement cost.