I have the following
clarifications to offer:
1. The first query was
regarding adequacy/inadequacy of milk production. The mother
"felt" that feeding was adequate. The baby however had lost
38% of birth weight. Subsequently, the baby needed supplementary feeds.
These factors indicate that the feeding and breast milk was inadequate.
2. As mentioned, low
urine osmolality in the presence of dehydration made us suspect diabetes
insipidus (DI) and therefore the child was investigated further.
3. (a) We agree that
fluid deprivation should have caused increase in serum osmolality. Our
impression is that water deprivation test was inadequate and therefore
there was no increase in serum osmolality. The decrease from 294 to 290
mosm/kg is marginal and may not be significant. (b) Water deprivation
test was terminated as we felt that it was not safe for the neonate.
Infact water deprivation and vasopression test should not be done in
neonates. We attempted to do both under supervision and monitoring
because we felt that this baby had DI. We agree that no change in urine
osmolality after fluid deprivation and vasopresin could suggest
nephrogenic DI. However, there was nothing to suggest nephrogenic DI and
the baby did well on follow up without any treatment and hence we have
ruled out nephrogenic DI. The renal scan was also normal. (c) The timing
of the two sets of investigations could have been different - hence the
discrepancy between actual and calculated osmolality.
4. We entirely agree
regarding the author’s suggestion that baby went into shock possibly
due to water deprivation rather than vasopression administration -
infact we reiterate that these tests should not be done in neonates. We,
however, do not agree that hypernatremia with elevated serum osmolality
and low urine osmolality is sufficient to diagnose DI.
5. We have mentioned that
we could not do the breast milk sodium. We ourselves were not very
convinced that this could be due to inadequate breast feeding initially
- hence the detailed evaluation. We still maintain that the
hypernatremia in this child was due to inadequate breast milk. The
polyuria could be due to a high output renal failure. What favored the
diagnosis was a normal follow up and literature review.
