Use of Copeptin Levels to Predict the Resolution of Transient Postoperative SIADH

Abstract

<b><i>Background:</i></b> Copeptin levels reflect vasopressin activity and help classify osmoregulatory disorders. There is limited pediatric experience using copeptin to diagnose and manage diabetes insipidus, syndrome of inappropriate antidiuretic hormone secretion (SIADH), and bi- or tri-phasic postsurgical osmoregulatory disorders. In this report, we describe serial copeptin levels in an infant who developed transient SIADH after neurosurgery. <b><i>Case Description:</i></b> A 4-month-old infant with no prior pituitary dysfunction underwent endoscopic fenestration of a large arachnoid cyst (3.5 × 4.7 × 3.8 cm). He developed SIADH on postoperative day 4 with seizures, hyponatremia (sodium 121 mmol/L), and concentrated urine (535 mOsm/kg). His initial copeptin level was inappropriately high in the context of his hyponatremia. Copeptin levels decreased as his SIADH resolved. Serial copeptin levels correlated to the infant’s increased ability to dilute urine. <b><i>Conclusion:</i></b> Copeptin levels in this infant are consistent with levels described in adults and older children. Obtaining copeptin levels may improve providers’ ability to quickly diagnose and manage SIADH amongst other heterogeneous causes of hyponatremia. Lastly, trending copeptin levels improved providers’ ability to monitor SIADH progression, and may allow preemptive fluid titration for children with bi- or tri-phasic shifts in osmoregulation after neurological procedures.

Copeptin: Utility in Paediatric Patients with Hyponatraemia

“…Copeptin levels will be elevated in patients with sodium depletion [8], and while our patients were not felt to be fluid deplete, in the absence of more sophisticated measures of fluid and sodium status, it is possible that these are also contributing factors to the increased copeptin level. A recent case report has "tracked" the change in copeptin concentrations in SI-ADH with time, although it is not clear whether this affected management directly [9].…”

“…The role of copeptin when investigating hyponatraemic patients is less clear with some authors suggesting that it is of limited value [8], while others suggest that it may be of diagnostic benefit in the context of the syndrome of inappropriate antidiuretic hormone secretion (SIADH) [9]. The extent to which a copeptin value impacts on management is less clear.…”

Fluid management in hospitalized pediatric patients

“…Achieving this fluid restriction yet providing optimal calories for growth is especially challenging in younger children and infants. Often a very high–calorie formula or higher dextrose content is needed in infants with SIADH 92 . Lastly, it is important in a child with chronic hyponatremia to avoid raising the sodium abruptly for risk of central pontine myelinolysis.…”

“…Often a very high-calorie formula or higher dextrose content is needed in infants with SIADH. 92 Lastly, it is important in a child with chronic hyponatremia to avoid raising the sodium abruptly for risk of central pontine myelinolysis.…”