A Case Report of Atypical Hyponatremia Caused by Diarrhea Following a Course of Ferrous Sulfate Supplements

Hyponatremia, defined as a serum sodium level less than 135 mg/mL, can be euvolemic, hypovolemic, or hypervolemic. Its presentation can be subtle or severe depending on whether the hyponatremia is acute or chronic. This case investigates a geriatric patient who suffered diarrhea and hyponatremia following a course of ferrous sulfate pills for anemia treatment. Given that ferrous sulfate pills usually result in constipation, this presentation was abnormal. Literature review and comparison to prior atypical situations resulted in the conclusion that the patient’s diarrhea was likely a result of her Crohn’s diagnosis. The subsequent resulting hyponatremia was likely due to this diarrhea coupled with her prescription thiazide diuretic which can cause hyponatremia as a common side effect. This report allows for physicians to understand potential causes behind atypical electrolyte abnormalities in their patients and hence, find an effective treatment plan.