PMC9246092_01
Changes in serum Na and urine output with DDAVP administration in case 1. While receiving vasopressin, this patient maintained a stable serum Na level, but with the discontinuation of vasopressin, hypernatremia and large volume UOP developed, consistent with DI. DDAVP administration began on hospital day 44, followed by normalization of UOP and serum Na. DI = diabetes insipidus; Na = sodium; UOP = urine output.
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F1
The patient was started on DDAVP at 2 mcg intravenously every 6 hours, which resulted in successful correction of his sodium and normalization of UOP over the subsequent 48 hours (Figure 1).
PMC9246092_02
Changes in serum Na and urine output with DDAVP administration in case 2. With the discontinuation of vasopressin, this patient's serum Na level increased by 21 mmol/L in the span of 24 hours with a urine output of almost 5 L. Despite the confounding factor of intravenous Lasix affecting the urine output, the degree of polyuria seen on HD 50 when vasopressin was discontinued is out of proportion to the quantity of Lasix given. DDAVP was given on HD 51, followed by normalization of UOP and serum Na. HD = hospital day; Na = sodium; UOP = urine output.
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F2
UOP was 4.9 L in the 24 hours prior, though may have been augmented by furosemide (Lasix) administration (Figure 2). Uosm at this time was 97 mOsm/kg.