Influenza as a Cause of SIADH Related Hyponatremia: A Case Report

Abstract

Syndrome of Inappropriate Secretion of Antidiuretic Hormone (SIADH) is one of the most common causes of hyponatremia in hospitalized patients. The distinct aetiologies and co-morbidities associated with hyponatremia pose substantial challenges in identifying and managing this disorder. Several infectious causes of SIADH are reported but hyponatremia associated with SIADH and influenza virus infection is less commonly seen. We present a case of hyponatremia associated with influenza, which was subsequently diagnosed as SIADH. CAsE REPORtA 75-year-old paraplegic male presented to the Emergency Department complaining of non productive cough and chest pain for one day. Chest pain was generalized, moderate in intensity and exacerbated by cough. No additional symptoms were reported. He did not take any medications and denied smoking, alcohol consumption or drugs. He was paraplegic due to a gunshot wound injury at lumbar region of the back several years ago. He was afebrile, had a blood pressure of 107/69 mmHg, heart rate of 87 beats per minute and respiratory rate of 18 breaths per minute with oxygen saturation of 98% on room air. Physical exam was only significant for diminished muscle strength 0/5 in lower extremities bilaterally and absent deep tendon reflexes. Laboratory findings were significant for a white blood cell count of 19,340/µl with a left shift deviation (87.2% neutrophils) and serum sodium (Na) of 130 mEq/l. Baseline serum Na was 137 mEq/l noted on prior admission for a urinary tract infection four months ago. Kidney function test was normal. A chest x-ray did not show any infiltrates or masses. Urine legionella antigen test was negative. Electrocardiogram showed no abnormality. Rapid flu test was positive for influenza type A. Cultures of urine, sputum and blood were negative for any microbial pathogen. He was started on oseltamivir 75 mg twice daily and fluid restriction was recommended for hyponatremia. Urine work up was significant for a high urine osmolarity of 631 mOsm/kg, low serum osmolality of 261 mOsm/kg with normal urine electrolytes including urinary sodium 46mEq/l. Thyroid stimulating hormone and morning cortisol levels were normal. Chest and brain computed tomography scans were unremarkable. Since all workup for pulmonary and central nervous system disorders remained negative, the patient was diagnosed as having SIADH due to underlying Influenza A virus infection. Patient was followed up after three weeks in the clinic. Leukocytosis was resolved and repeat sodium levels were found to be normal.

COVID-19 Pneumonia: An Emerging Cause of Syndrome of Inappropriate Antidiuretic Hormone

“…Common lung pathologies such as pulmonary malignancy, severe obstructive lung disease, acute respiratory failure, and pneumonia are the prevalent disorders that can lead to SIADH [9]. Among viral infections, influenza has been identified as an underlying cause of SIADH [13][14]. In recent times, COVID-19 pneumonia has emerged as a causative factor for SIADH.…”

Rhinovirus infection presenting with symptomatic hyponatremia—Atypical presentation of a common infection

“…9 Additionally, secretion of other inflammatory cytokines like IL-1 beta, IL-2, and tumor necrosis factor alpha has been observed to enhance ADH release by stimulating parvocellular and magnocellular arginine vasopressin neurons. 10 The unique aspect of this case report is that the patient solely exhibited symptoms of hyponatremia, without typical respiratory symptoms like cough or shortness of breath associated with rhinovirus infections. Furthermore, no evidence suggested concurrent bacterial infection, which usually elevates inflammatory markers and cytokines that influence ADH release.…”

“…While hyponatremia has been linked to viral infections such as influenza, 3,10 the precise mechanisms for rhinovirus‐induced hyponatremia remain less understood. An inferred mechanism involves the induced inflammatory response often seen in viral infections 9 .…”

“…Inflammation has been correlated with elevated interleukin (IL)‐6 levels, known to stimulate hypothalamic magnocellular neurons to release ADH 9 . Additionally, secretion of other inflammatory cytokines like IL‐1 beta, IL‐2, and tumor necrosis factor alpha has been observed to enhance ADH release by stimulating parvocellular and magnocellular arginine vasopressin neurons 10 …”

Covıd-19 pnomonisi ile ilişkili uygunsuz antidiüretik hormon salınım sendromu olgusu

“…Akciğer malignitesi, şiddetli obstrüktif akciğer hastalığı, akut respiratuar hastalık ve pnömoni gibi sık görülen akciğer hastalıkları UADHSS ile birliktelik gösterebilir [8]. Viral enfeksiyonlar arasında influenza da tanımlanmıştır [9]. Varicella zoster virüs (VZV), sitomegalovirüs (CMV), herper simplex virüs (HSV) gibi viral enfeksiyonlarda da UADHSS görülebilmektedir.…”