Serum copeptin levels at day two after pituitary surgery and ratio to baseline predict postoperative central diabetes insipidus

Role of Early Postoperative Measurement of Copeptin in Prediction of Diabetes Insipidus Following Pituitary Surgery in Adults: A Systematic Review Plus Meta-analysis

BACKGROUND

Early diagnosis of diabetes insipidus (DI), a complication following pituitary surgery, can avoid catastrophic results such as lethargy or even death. Measurement of arginine vasopressin (AVP) may help the early diagnosis, but its direct assaying is challenging. Copeptin, which is co-secreted in equimolar quantities to AVP, is suggested to be a reliable marker in prediction of postoperative DI. Therefore, this systematic review plus meta-analysis aims to discover this possible role.

METHODS

Google Scholar, PubMed, Scopus, Web of Science, Embase, and Cochrane library were systematically searched up to August 2024. The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) and Problem/Population, Intervention, Comparison, and Outcome (PICO) guidelines were used. Two authors independently reviewed the eligible articles and assessed the quality of them. A meta-analysis was conducted to assess the discriminative performance of copeptin.

RESULTS

In total, 8 cohort studies including 1255 participants met the inclusion criteria. The median copeptin levels were significantly lower in DI groups compared with non-DI groups in all included studies (P < 0.005). Meta-analysis of areas under the curve demonstrated that early measurement of copeptin level had an accuracy of 0.791 (standard error: 0.0198, 95% CI: 0.752 to 0.830), which was statistically significant (P < 0.001).

CONCLUSIONS

Copeptin level was significantly lower in DI patients than in non-DI patients who underwent pituitary surgery. Early measurement, as soon as possible (from the first hour to 48 hours after the operation) of copeptin after pituitary surgeries has good, but not excellent, accuracy to exclude postoperative DI.

Impact Factors of Blood Copeptin Levels in Health and Disease States

OBJECTIVE

Copeptin, the C-terminal glycopeptide of provasopressin, is released into the circulation in an equimolar manner with arginine vasopressin (AVP) when fluid homeostasis changes or has somatic stress. Copeptin is considered a potential alternative to AVP due to its advantages in facilitating assays. Although there have been several studies and reviews that have focused on the marker potential of copeptin in diseases involving changes in AVP, studies on its characteristics and factors that may influence its secretion have not been reviewed before.

METHODS

We summarize the influencing factors associated with copeptin levels in healthy and disease states, show the changes in copeptin levels under different physiologic and pathophysiologic conditions, calculate the changes in copeptin levels under different physiologic and pathophysiologic conditions, and compare them according to the type of stimuli. We also report research advances in copeptin changes in the diagnosis and prognosis of endocrine-related diseases.

RESULTS

Males have higher copeptin levels. Decreased copeptin levels are mainly caused by reduced blood volume and some diseases (eg, obesity). Under normal physiologic conditions, the effects of stress, endocrine axis stimulation, and blood volume increase on copeptin levels gradually increase. Under severe disease conditions (eg, sepsis), copeptin would remain at consistently high levels under compound stimuli and these elevated levels are associated with a poor prognosis of the disease.

CONCLUSION

Summarizing the influencing factors of copeptin can help us better understand the biologic features of copeptin and the similarities and differences between AVP and copeptin.

Updates in hyponatremia and hypernatremia

PURPOSE OF REVIEW

Hyponatremia and hypernatremia are commonly encountered electrolyte abnormalities that require timely and careful intervention, as they can be associated with significant morbidity and mortality.

RECENT FINDINGS

This review article addresses the etiology, presentation, diagnosis, and management of both hyponatremia and hypernatremia, emphasizing the latest advancements and emerging trends in pediatric care.

SUMMARY

A methodical approach is needed to accurately assess and treat hyponatremia and hypernatremia. Both conditions continue to rely on serum and urine testing, however newer tests such as copeptin and stimulated testing may hold promise to further refine testing in the future.

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

BACKGRUOUND

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.

Copeptin analysis in endocrine disorders

Copeptin is cleaved from the same precursor as arginine vasopressin and is released in equimolar amounts with arginine vasopressin from the posterior pituitary in response to the same stimuli. Its level of stability in the blood, quick and simple analysis, and ease of automation make it much easier to analyze than arginine vasopressin, thereby offering a suitable alternative to measuring arginine vasopressin in endocrine disorders. Research has demonstrated the suitability of copeptin in adults for the differentiation of arginine vasopressin resistance and arginine vasopressin deficiency from primary polydipsia, in addition to the early identification of arginine vasopressin deficiency following pituitary surgery; however, further research is still required in the Syndrome of Inappropriate Antidiuretic Hormone (SIADH) and the pediatric population.