What if ADH-ditionally there’s Mycoplasma pneumoniae?

The inappropriate antidiuretic hormone syndrome (SIADH) is characterized by an abnormal increase in ADH release without the appropriate physiological stimuli, leading to dilutional hyponatremia, decreased serum osmolality, and increased urinary osmolality and sodium excretion. We describe the case of a 12-year-old girl who developed incomplete SIADH during her Intensive Care Unit (ICU) admission in the context of community-acquired pneumonia with a positive PCR for M. pneumoniae. SIADH is a common cause of transient hyponatremia in children with respiratory infections. It has been associated with more severe disease, prolonged hospital stays, and a higher likelihood of ICU admission, making it essential to consider electrolyte imbalances in the management of these patients.