Golang: cast an interface to a typed variable dynamically

In go, is it possible to cast variables dynamically somehow?

For example, if a simple cast would be:

var intAge  = interfaceAge.(int)

What if I do not know that age is an int in advance? A simple way of writing it would be

var x = getType()
var someTypeAge = interfaceAge(.x)

Is there a way of achieving something like this? The reflect package gives some ways of determining or casting a type at runtime - but I couldn't find anything like the above mentioned (a generic scheme that would work for all types).