using DotNetNuke.Entities.Profile;

string _value = GetUserProfilePropertyValue("MyCustomProfileField").ToString();

        public string GetUserProfilePropertyValue(string propertyName)
        {
            string value = null;
            ProfilePropertyDefinition ppd = UserInfo.Profile.GetProperty(propertyName);

            if (ppd == null)
            {
                value = "";
            }
            else
            {
                value = ppd.PropertyValue;
                if (value == null)
                {
                    if (string.IsNullOrEmpty(ppd.DefaultValue))
                    {
                        value = string.Empty;
                    }
                    else
                    {
                        value = ppd.DefaultValue;
                    }
                }
            }
            return value;
        }