Endocrinol Metab.  2024 Feb;39(1):164-175. 10.3803/EnM.2023.1792.

Preoperative Serum Copeptin Can Predict Delayed Hyponatremia after Pituitary Surgery in the Absence of Arginine Vasopressin Deficiency

• Kang H
• Park SS
• Kim YH
• Lim HS
• Lee MK
• Lee KR
• Kim JH
• Kim YH

• KMID: 2552807
• DOI: http://doi.org/10.3803/EnM.2023.1792

Abstract

Background
Delayed postoperative hyponatremia (DPH) is the most common cause of readmission after pituitary surgery. In this study, we aimed to evaluate the cutoff values of serum copeptin and determine the optimal timing for copeptin measurement for the prediction of the occurrence of DPH in patients who undergo endoscopic transsphenoidal approach (eTSA) surgery and tumor resection.
Methods
This was a prospective observational study of 73 patients who underwent eTSA surgery for pituitary or stalk lesions. Copeptin levels were measured before surgery, 1 hour after extubation, and on postoperative days 1, 2, 7, and 90.
Results
Among 73 patients, 23 patients (31.5%) developed DPH. The baseline ratio of copeptin to serum sodium level showed the highest predictive performance (area under the curve [AUROC], 0.699), and its optimal cutoff to maximize Youden’s index was 2.5×10^–11, with a sensitivity of 91.3% and negative predictive value of 92.0%. No significant predictors were identified for patients with transient arginine vasopressin (AVP) deficiency. However, for patients without transient AVP deficiency, the copeptin-to-urine osmolarity ratio at baseline demonstrated the highest predictive performance (AUROC, 0.725). An optimal cutoff of 6.5×10^–12 maximized Youden’s index, with a sensitivity of 92.9% and a negative predictive value of 94.1%.
Conclusion
The occurrence of DPH can be predicted using baseline copeptin and its ratio with serum sodium or urine osmolarity only in patients without transient AVP deficiency after pituitary surgery.

Keyword

Copeptins; Arginine vasopressin protein; Hyponatremia; Pituitary neoplasms

Figure

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  Fig. 1. Serum copeptin concentration according to the time points of sample collection and the occurrence of delayed postoperative hyponatremia (DPH) (A) before surgery (baseline), (B) 1 hour after extubation, (C) postoperative day 1, (D) day 2, (E) day 7, and (F) day 90.

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  Fig. 2. Receiver operating curve analysis for the prediction of delayed postoperative hyponatremia. (A) Predictive performance and cutoff of the absolute value and ratio of preoperative copeptin to serum sodium and urine osmolarity in overall patients (n=73) and (B) in patients with no transient central diabetes insipidus (n=46). AUC, area under curve.

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