Frequency and severity of hyponatremia in healthy children with acute illness.

Background: Hyponatremia can occur in the acute phase of any illness through various mechanisms. However, the frequency and severity of hyponatremia are not well known across a broad range of illnesses including medical and surgical diseases and trauma.

Methods: The present, retrospective chart review was conducted at Tokyo Metropolitan Children's Medical Center from 2018 to 2019. Included were healthy children aged < 16 years with an acute illness, who were urgently admitted, and had their serum sodium level measured on arrival.

Results: In total, 2717 patients were urgently admitted and had their serum sodium level measured. Of these, 1890 were included. Hyponatremia was found in 260 patients (13.8%). The most common hyponatremic disease was type 1 diabetes mellitus (69%) followed by acute infectious encephalopathy (60%), pyogenic arthritis (60%), and Kawasaki disease (51%). Kawasaki disease, seizure, urinary tract infection, acute appendicitis, lower respiratory tract infection, and acute gastroenteritis were associated with a significantly lower serum sodium value than cases of fracture comprising a control group. Conversely, acute bronchial asthma exacerbation (3%), anaphylaxis (0%), intussusception (0%), acute scrotal disease (0%), head injury (1%), and fracture (0%) were very infrequently associated with hyponatremia.

Conclusions: The present study determined the frequency and severity of hyponatremia in various, acute, pediatric illnesses, including medical and surgical diseases and trauma. Despite reports of respiratory distress and pain inducing vasopressin secretion, hyponatremia was rarely observed on arrival in patients with acute bronchial asthma exacerbation, anaphylaxis, intussusception, acute scrotal diseases, head injury, or fracture.