syndrome of inappropriate secretion of antidiuretic hormone ( siadh ) is a common cause of hyponatremia .
although it has been associated with different pulmonary infections , there have been only few case reports describing the association of siadh with influenza .
we report a case of siadh in a patient with influenza who was successfully treated with fluid restriction .
it is essential for clinicians to be aware of the association between influenza and siadh .
syndrome of inappropriate secretion of antidiuretic hormone ( siadh ) is one of the most common causes of hyponatremia in hospitalized patients , with a prevalence as high as 35% .
it is characterized by the impairment of urinary dilution in the absence of any renal disease or any identifiable nonosmotic stimulus that induces antidiuretic hormone ( adh ) release .
although siadh has been known to be associated with different pulmonary infections , only rarely has it been reported with influenza .
we present a case of hyponatremia associated with influenza , which was subsequently diagnosed as siadh .
a 65-year - oldmale presented to the emergency department with low - grade fever and productive cough for 2 days .
he did not have any neurological symptoms , abdominal pain , nausea , vomiting , change in bowel movements , or loss of appetite or weight .
he did not have any history of recent surgery , central nervous system disorders , malignancy , or known pulmonary disease .
on examination , he had a temperature of 102.4f , heart rate 120/min , respiratory rate 24/min , blood pressure 110/60 mmhg without orthostatic vital signs , and oxygen saturation 96% on room air .
laboratory examination revealed a serum sodium of 122 meq / l ( 135 - 145 ) , blood urea nitrogen ( bun ) 11 mg / dl ( 8 - 24 mg / dl ) , creatinine 1.35 mg / dl ( baseline 1.2 - 1.3 ) , plasma osmolality 276 mosm / kg ( 280 - 290 ) , urine specific gravity of 1.029(1.002 - 1.030 ) , urine osmolality 777 mosm / kg , urine sodium 63 meq / l , thyroid - stimulating hormone ( tsh ) 3.011 iu ( 0.5 - 5.0
mu / l ) , and random serum cortisol 20.2 g / dl ( 7 - 25 g / dl ) .
the chest x - ray did not show any infiltrate , consolidation , or mass .
the nasal swab polymerase chain reaction was positive for influenza a. urinary antigens for legionella , mycoplasma , and streptococcus were negative .
a diagnosis of siadh was made and his hyponatremia was corrected gradually in 3 days with fluid restriction o less than 800 ml / day . at 2 weeks
thus , a careful history to rule out other causes like malignancy , pulmonary conditions , central nervous system lesions , and medications is essential in the evaluation of any patient suspected with siadh .
it has been reported in many pulmonary infections including asthma , atelectasis , acute respiratory failure , and pneumothorax .
influenza has been implicated as a cause of siadh previously , but there is no published data regarding the actual incidence of siadh in these patients .
our patient was diagnosed with siadh based on : 
 hypoosmolar hyponatremia;urine osmolality > 100 mosm / kg;urine sodium concentration > 40 meq / l;euvolemic state ; andnormal renal , thyroid , and adrenal function . 
 
hypoosmolar hyponatremia ; urine osmolality > 100 mosm / kg ; urine sodium concentration > 40 meq / l ; normal renal , thyroid , and adrenal function .
failure of improvement of serum sodium with intravenous normal saline further confirmed the diagnosis of siadh .
although the exact pathogenesis for siadh in influenza is unknown , it is thought to be related to the secretion of proinflammatory cytokines .
interleukin ( il)-2 , il-6 , il-1 , and tumor necrosis factor ( tnf)- have been reported to stimulate parvocellular and magnocellular neurons to secrete more adh ; thus causing siadh .
fluid restriction is the main treatment modality in siadh , with a suggested goal intake of less than 800 ml / day .
further treatment options depend on the severity of hyponatremia and the presence of other related symptoms . in the presence of severe or symptomatic hyponatremia , hypertonic saline
goal should be to raise serum sodium less than 10 - 12 meq / lin 24 h to ovoid the potential complication of osmotic demyelination with rapid correction .
oral salt tablets and loop diuretics may also be added if optimum response is not seen with fluid restriction alone .
our patient 's siadh was thought to be secondary to influenza , which was treated with oseltamivir and led to steady improvement in the patient 's serum sodium levels . in conclusion
, clinicians should be cognizant of the association between influenza and siadh to allow for accurate diagnosis and treatment of this condition .
further studies are needed in future to find out the incidence and pathogenesis of siadh in patients with influenza .
although treatment depends on the severity of hyponatremia and associated symptoms , fluid restriction remains the cornerstone of therapy .
 context : syndrome of inappropriate secretion of antidiuretic hormone ( siadh ) is a common cause of hyponatremia . 
 although it has been associated with different pulmonary infections , there have been only few case reports describing the association of siadh with influenza.case report : we report a case of siadh in a patient with influenza who was successfully treated with fluid restriction.conclusion:it is essential for clinicians to be aware of the association between influenza and siadh . 
Context:
Case Report:
Conclusion:
Introduction
Case Presentation
Discussion