It is pretty through. It consists of testing done by doctors for ,
Height
Weight
Vision
Hearing
Blood analysis
Urine analysis
Electrocardiogram
Chest x-ray
Drug screening
Blood pressure
if these are normal, then overall one can assess that the person is healthy.
Beyond this, everybody has some genetic disorder or other.
Still not that comprehensive to diagnose rare disorders like Gigantism, you need to consult specialized experts of this field to determine its presence.