R – Only updating filled in properties

Is there a way to have NHibernate only update the fields that don't have the default value filled in? Say we have this simple class:

public class Person
{
    public int Id { get; set; }
    public string Name { get; set; }
    public int Age { get; set; }
}

We also have a standard NHibernate mapping using properties for each field and Id for the Id field.

Say we want a page to just update the Name, so we send down the Id, store it in a hidden field, and show a text box for the name. The user modifies the name and hits save. We POST back, new up a Person object, and assign the incoming Id and Name. We then tell NHibernate to update the database.

Problem is, the Age obviously gets set back to 0 in the database as it wasn't filled in coming back from the POST. The most obvious way around this is to send the Age value to the page, store it in a hidden field, and fill it back in before saving. That works fine until you get quite a few more properties on your object and only want to modify a hand full of them on the screen (or a large list of Person objects, which might require storing lots of values in hidden fields).

So back to the subject of the question: is there a way to tell NHibernate to basically ignore the Age property since it'd have a default value (0) before being updated, or am I stuck with a metric ton of hidden fields to keep the existing values?