Copeptin measurement potential tool to predict Diabetes Insipidus after pituitary surgery

Copeptin analysis can be used to predict which patients are at risk of developing Diabetes Insipidus following transsphenoidal adenomectomy (TSA), a recent study has shown

The has been published in Research Square journal

Pituitary gland surgery is often accompanied by a postoperative complication of diabetes insipidus. It could be an immediate after effect or may occur transiently over time.

Efficient diagnosis of Diabetes Insipidus is limited by the challenge of directly assaying arginine vasopressin (AVP),which has a short half-life in vivo, is unstable ex vivo even when frozen. It is also affected by a slow or incomplete separation from platelets.

The study involved collecting plasma samples from 78 patients undergoing elective transsphenoidal adenomectomy (TSA) at the John Radcliffe Hospital (Oxford University Hospitals NHS Foundation Trust, Oxford, UK) between November 2017 and June 2020.

Patients were made to undergo preoperative magnetic resonance imaging (MRI) of the pituitary with contrast and all scans were reported by a Neuroradiologist. Lesions < 1 cm in diameter were classified as microadenomas and those≥ 1 cm in diameter classified as macroadenomas.

A single Neurosurgical team carried out all the transsphenoidal adenomectomies. Operations were carried out under general anesthetic using endoscopic techniques.

It was suspected that the patient may have developed Diabetes Insipidus if their urine output was more than 200 mL/hour for 3 consecutive hours or more than 3 L per day, and this was confirmed with biochemistry showing high plasma sodium (> 145 mmol/L) and osmolality (> 295 mosmol/kg) with inappropriately low urine osmolality.

The researchers found the following  

78 patients undergoing transsphenoidal adenomectomy had a median age of 55 (range 22–85), with 41 of 78 being men (52.6%).

Two patients had estimated glomerular filtration rates < 30 ml/min/1.73m2 , and neither of these developed Diabetes Insipidus.

The majority of lesions  (72/78; 92.3%) were macroadenomas, while histologically gonadotroph tumors were the most common (37/78; 47.4%).

"We confirm that post-pituitary surgery copeptin measurement is useful to exclude Diabetes Insipidus early postoperatively and propose it as a potential tool to identify patients suitable for early discharge. It will be important to conduct future work on earlier sampling times, with real-time assay, and combine these results with other clinical and biochemical parameters to provide a robust dataset at 24 hours post-pituitary surgery enabling selection of patients for safe early discharge", the researchers concluded.

You can read the study by clicking on the following link 

DOI: https://doi.org/10.21203/rs.3.rs-1372750/v1