Any medication can cause nausea and/or decreased appetite.  The ones
mentioned are not special in this area.  As far as I know, there is
nothing specific about these medications which would cause decreased
rate of growth.  However, a baby who goes to the breast every two
hours does not sound as if he has a decreased appetite.

The baby is best to get more breastmilk, not fortifier, unless this
cannot be avoided.  In the first place, the fortifiers are relatively
high in mineral content (that's why they are given, for the extra
calcium, for example), which a baby with some renal insufficiency can
do without, though it may not make much difference in his situation.
But, if this baby is allergic to cow's milk, fortifier is made with
that.  That is why we have to push neonatologists to insist on human
milk based fortifiers.  If the companies feel they can make money with
it, we will have it.  If it is not possible for the baby to get more
breastmilk, the mother could supplement (with an SNS), something like
polycose (which is starch, essentially).

The mother could increase the baby's intake of breastmilk by using
breast compression to keep up the flow of milk.  Metoclopramide
(Reglan) is also a possibility.

The mother's milk has enough calories in it for a baby at five months
of age.  GRRRR.

If the baby's one kidney only is involved, the baby can have a
perfectly normal life with one good kidney.  It is quite possible that
the hypertension will disappear with removal of the affected kidney,
though this is not guaranteed.

Jack Newman, MD, FRCPC