Some pediatric patients with enuresis may still have nocturnal polyuria despite therapy with desmopressin.

Possible causes of nocturnal polyuria:

(1) correctable cause without the need to increase the dose of desmospressin

(2) insufficient dose of desmopressin

(3) desmopressin resistance


Correctable causes:

(1) noncompliance

(2) failure to empty the bladder before going to bed

(3) administration of desmopressin less than 1 hour before last void before sleep

(4) excessive fluid intake after or during the hour after the desmopressin dose

(5) constipation


Causes of desmopressin resistance:

(1) abnormality of maximal concentrating capacity

(2) increased nocturnal osmotic excretion

(3) nycthemeral (24 hour) rhythm of prostaglandins

(4) calciuria

(5) sodium excretion

(6) sleep pattern

(7) dietary intake

(8) increased GFR

(9) nephrogenic diabetes insipidus

(10) psychiatric disorder


Most cases of desmopressin-resistance should be referred to a specialist.

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