$defaults = civicrm_api('Setting', 'getdefaults', $params);
$fields = civicrm_api('Setting', 'getfields', $params);
$fields = $fields['values'];
$defaults = civicrm_api('Setting', 'getdefaults', $params);
$fields = civicrm_api('Setting', 'getfields', $params);
$fields = $fields['values'];