PES Syndrome Presenting as Severe Hyponatremia in an Asymptomatic Septuagenarian

BACKGROUND: Hyponatremia is commonly seen in hospitalized patients. In euvolemic individuals, syndrome of inappropriate antidiuretic hormone secretion (SIADH) is a common differential. However, before establishing a diagnosis of SIADH, it is imperative to evaluate for hypocortisolism and hypothyroidism. The finding of endocrine abnormalities determined to be of pituitary origin should prompt evaluation by brain MRI. Furthermore, primary empty sella (PES) is commonly seen as an incidental neuroradiological finding. However, PES in association with endocrine abnormalities is recognized as a separate entity called primary empty sella syndrome (PESS). Case Presentation. We report the case of a 71-year-old male sans neurological symptoms who presented to us with severe hyponatremia in whom we used a stepwise approach which led us to the diagnosis of PESS. This methodical approach was crucial for timely correction of the endocrine abnormalities which in turn rectified hyponatremia. Intriguingly, the presence of an ectopic pituitary which is a very rare entity and the sudden manifestation of his underlying endocrine deficiencies in the 8th decade of life make this clinical scenario highly unusual. CONCLUSION: Clinicians should be aware that absence of an orderly approach to workup presumed SIADH or an assumption of PES (instead of PESS) could both lead to serious consequences in the face of missed endocrine deficiencies.