ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Endocrine Abstracts (2019) 63 EP93 | DOI: 10.1530/endoabs.63.EP93

Etiology of syndrome of inappropriate antidiuretic in patients on parenteral nutrition: prospective multicenter study

Ana Ortolá Buigues1, Emilia Gómez Hoyos1, María Dolores Del Olmo García2, Ana Herrero Ruiz3, Julia Álvarez Hernández4, Cristina Tejera Pérez5, Sandra Herranz Antolín6, Irene Bretón Lesmes7, Miguel Angel Martínez Olmos8 & Daniel De Luis Román1

1Hospital Clínico Universitario de Valladolid, Valladolid, Spain; 2Hospital Universitario Severo Ochoa, Leganés, Spain; 3Hospital Universitario de Salamanca, Salamanca, Spain; 4Hospital Universitario Príncipe de Asturias, Alcalá de Henares, Spain; 5Complejo Hospitalario Universitario de Ferrol, Ferrol, Spain; 6Hospital General Universitario de Guadalajara, Guadalajara, Spain; 7Hospital General Universitario Gregorio Marañón, Madrid, Spain; 8Complejo Hospitalario Universitario de Santiago de Compostela, Santiago de Compostela, Spain.

Introduction: Syndrome of Inappropriate Antidiuretic (SIAD) is the most frequent cause of hyponatremia in parenteral nutrition (PN) patients. Moreover, SIAD may be caused by multiple etiologies (drugs; pulmonary, neurological or abdominal disorders; malignant disease; idiopathic…). Our objective was to evaluate the main etiologies of SIAD in patients receiving PN.

Methods: Prospective, non-interventional, multicenter study in 19 Spanish hospitals. Forty- seven patients with SIAD-induced hyponatremia while receiving PN over a 9-month period were recruited. Hyponatraemia was defined as a Serum Na level (SNa) <135 mmol/l. Patient data collected included sex, age, prior comorbidities, use of drugs, cause of hospital admission and serum sodium levels (SNa) before and following PN initiation. Parameters for study of hyponatremia were also included, such as clinical volemia, the presence of pain, nausea, gastrointestinal losses, edema, measurement of creatinine, plasma and urine Osmolality, urinary electrolytes, cortisolemia, and thyroid stimulating hormone.

Results: 59.6% were men. The average age was 66.9 (S.D. 11.5). 53.2% had hyponatremia before PN initiation. All patients had diagnostic criteria for the SIAD. Most probable etiologies of SIAD were: malignant disease (55.3%), drugs (23.4%: antidepressants, pregabalin/gabapentin, opiatas,\..), abdominal disorders (10.6%), pulmonary disorders (2.1%), and idiopathic (2.1%). Etiology of SIAD could not be assessed in 3 patients. No patient had SIAD caused by neurologic disorder.

Conclusions: The diagnostic approach of etiology of SIAD is complex. Multiple clinical factors must be taken into account. In our series of patients receiving PN, paraneoplasic secretion of antidiuretic hormone was the most frequent cause of SIAD-induced hyponatremia. Other etiologies were different than in the general population, probably related to specific clinical features of patients on PN.