Diabetes insipidus (DI) is a clinical disorder of water metabolism in the human homeostasis, commonly resulting from the deficiency of antidiuretic hormone (ADH) or due to the inability of the kidney to respond normally to ADH. DI manifests as passing diluted copious amount of urine by the patient.1 DI is classified as central or nephrogenic and pregnancy induced. In central DI, posterior pituitary gland fails to secrate ADH resulting in an absolute shortage. In contrast, nephrogenic DI is when the renal receptors do not respond adequately to an adequate level of ADH. Finally, pregnancy induced DI is when placenta consumes most of the secreted ADH, leading to ADH deficency.2 DI is common after the pituitary gland surgeries.3 There are a few case reports of DI after general surgical procedures.4 Although polyuria is common in the post-operative period, it is important to diagnose DI to prevent severe dehydration and life-threatening electrolyte imbalance. We report two unusual cases of DI during the perioperative period requiring hydration and intravenous desmopressin.
Case1: A 49 years old healthy male was diagnosed with cervical vertebral disc prolapse (C5-6) and planned for an elective cervical discectomy and cage fusion. General anaesthesia was induced with etomidate and fentanyl, trachea was intubated under the effect of rocuronium. In addition, the patient received ketamine and cefazolin during induction. Anaesthesia was maintained by propofol and remifentanil target-controlled infusion (TCI) striving for a BIS (Bispectral Index) between 40 and 60. Foley’s catheter was inserted before positioning the patient, for intraoperative measurement of urine output (UOP). UOP was 50 to 70 ml for first two hours. During the procedure his hemodynamics were stable. In the 3rd hour of surgery he became polyuric and passed 700 to 800ml diluted urine in next 2 hours until the surgical procedure was over. He did not receive any diuretic or mannitol. He was started on 50ml/hour of 0.45% saline and shifted to post anaesthesia care unit. Still he remained polyuric and kept passing 300 and 400ml of diluted urine for the next 2 hours (Figure1). Finally, he developed hypernatremia although his renal functions were with in normal range and urine specific gravity was <1005, diagnosed to have central diabetes insipidus and was given intravenous (IV) 2 micrograms (µgrams) of desmopressin. For the next hours his urine became concentrated and urine output dropped to 50, 60 and 70ml/hour respectively (Figure1). Next day he was transferred to high dependency unit (HDU), remained stable, from there discharged home and followed up in neurosurgical outpatient clinics.
Case 2
A 36-year-old healthy male presented with on and off headache. After neuroimaging (Computer tomography-CT and MRI-magnetic resonance tomography) a cyst in the third ventricle was diagnosed. Due to this finding, he underwent right frontal craniotomy and excision of ventricular cyst. Anaesthesia was induced with propofol and remifentanil, trachea was intubated under the effect of rocuronium. He received cefazolin during the induction of anaesthesia. Anaesthesia was maintained with remifentanil and propofol TCI-infusion. Patient remained hemodynamically stable. His urine output remained 50 to 70 ml/hour during the surgical period. After the procedure the patient was transferred to the surgical intensive care unit (SICU) for further monitoring. In the SICU during the 1st and 2nd hour he passed 600ml and 700ml of diluted urine respectively (figure 2). His serum sodium increased to 148 mmol/litre. However, his renal functions were normal and urinary specific gravity was <1005. The patient was started on 100ml/hour of 0.45% saline and desmopressin 2 µgram was administrated intravenously. From the next hour his urine became concentrated and urine output dropped to 50 to 100ml/hour. The patient remained hemodynamically stable and serum sodium became normal. The next day he was transferred to the ward and from there discharged home. He was followed up in the neurosurgical outpatient clinic was without any issues.