Patients affected by
nephrogenic diabetes insipidus (NDI) can present with hypernatremic
dehydration, and first-line
rehydration schemes are completely different from those largely applied in usual conditions determining a mild to severe
hypovolemic dehydration/
shock. In reporting the case of a patient affected by NDI and presenting with severe
dehydration triggered by acute pharyngotonsillitis and
vomiting, we want to underline the difficulties in managing this condition. Restoring the free-water plasma amount in patients affected by NDI may not be easy, but some key points can help in the first line management of these patients: (1) hypernatremic
dehydration should always be suspected; (2) even in presence of severe
dehydration, skin turgor may be normal and therefore the skinfold recoll should not be considered in the
dehydration assessment; (3) decreased thirst is an important red flag for
dehydration; (4) if an incontinent patient with NDI appears to be dehydrated, it is important to place the
urethral catheter to accurately measure urine output and to be guided in parenteral fluid administration; (5) if the intravenous route is necessary, the more appropriate fluid replenishment is 5%
dextrose in water with an infusion rate that should slightly exceed the urine output; (6) the
0.9% NaCl solution (10 mL/kg) should only be used to restore the volemia in a shocked NDI patient; and (7) it could be useful to stop
indomethacin administration until complete restoration of hydration status to avoid a possible worsening of a potential prerenal
acute renal failure.