Regexp - Removing From URL

I am weak when it comes to regexp but hoped someone might know in this case.
I am trying to take a url like this :

something.lasso?blah=blah&blah2=blah2&sort=hello&blah3=blah3

And remove the &sort=XXX without hurting the rest of the url. The parameter
to be replaced would be a parameter passed to a function. Here is what I
have so far:

function refresh(item) {
current = document.location.href;
if(current.match(item.name+'='))
//pseudo code here
//current.replace(item.name regexp , '');

return (current + "&" + item.name + "=" + item.value);

This function would be fired like this :

All <input type="radio" name="show" value="all"
onclick="document.location=refresh(this);">
Mine <input type="radio" name="show" value="mine"
onclick="document.location=refresh(this);">