Acute and Chronic Posterior Pituitary Insufficiency Among Traumatic Brain Injury Patients at a Tertiary Care Center

Background: Traumatic brain injury (TBI) is the leading cause of death and disability in young adults. Disorders of salt and water balance are the most commonly recognized medical complications in the immediate post-TBI period and contribute to early morbidity and mortality. Objective: We aimed to evaluate the prevalence of acute (during hospital stay) and chronic posterior pituitary dysfunction in patients of head injury admitted at our tertiary care hospital. Study Design: Prospective, Observational study. Participants: 136 patients, attending tertiary care in North India with TBI with radiological evidence of head injury. Methodology: The severity of brain injury was assessed by the Glasgow Coma Scale (GCS), and Modified Rankin Scale (MRS) score at the time of admission. Lab measurements, apart from routine CBC and biochemical tests, included tests of serum and urinary osmolality, serum sodium, cortisol, and thyroid function test during the hospital stay. All patients were monitored closely during the hospital stay. Surviving patients were evaluated at 3, 6, and 12 months of follow-up. Urinary output and water deprivation tests were done to determine chronic posterior pituitary dysfunction. The results were compared against normative data obtained from 25 matched, healthy controls. Serum & urinary osmolality was measure by the freezing point method. Diabetes insipidus (DI) and Syndrome of inappropriate ADH secretion (SIADH) were diagnosed according to standard criteria. Results: Of 136 patients admitted, 61 (44.85%) had a mild head injury (GCS, ≤8), 47 (35.55%) had a moderate injury (GCS, 9-12), and 27 (19.85%) had a severe injury (GCS, 13-15). DI occurred in 10 patients (7.4%), while SIADH was observed in 4 patients in the immediate TBI period. Risk factors for diabetes insipidus were GCS of ≤ 8 at admission, midline shift, and surgical intervention. DI was an independent risk factor for death. There was a negative correlation between the presence of DI and GCS score (r, -0.367). Most of the patients with DI (8 out of 10) died during the hospital stay. One patient persisted to have partial diabetes insipidus and another one SIADH at three months post-TBI; both patients had recovered at six months of follow-up. No new case of DI or SIADH occurred on the follow up to 12 months. Conclusion: The incidence of acute DI in severe head injury (GCS ≤ 8) could be an indicator of the severity of TBI, and associated with increased mortality as most of our patients died during the hospital stay.