How to get Hidden Column Value in GridView

protected void btnSelect_Click(object sender, EventArgs e)
{

    Button btn = (Button)sender;
    DataControlFieldCell dfc = (DataControlFieldCell)btn.Parent;
    GridViewRow gvr = (GridViewRow)dfc.Parent;
    Label lblAddressId = (Label) gvr.FindControl("lblAddressId");

    int iAddressId = (int)  lblAddressId.Text;
    lstAddressId.Add(iAddressId);

}