These results may be significant of disease or they may be within normal limits (you haven't given the figures).
The low creatinine is not that significant in itself, but the low calcium does need some explanation and the first port of call to explain this would be parathyroid investigations as suggested by you doctor.
Unusual, but one can have disorders of the parathyroid glands which are four small glands attached to the thyroid glands in the neck which control amongst other things calcium in the body.
Nothing drastic comes to mind at this stage.