A 50-year-old male presents with lethargy and difficulty concentrating. His blood test shows a sodium level of 125 mEq/L. What could be the potential causes, and what are the next steps?
This patient's low sodium level indicates hyponatremia, which can cause symptoms like lethargy and confusion. It can be due to a variety of conditions, including heart failure, liver cirrhosis, kidney disease, SIADH, or excessive water intake. Further assessment of the patient's fluid status, urine electrolytes, and assessment of the patient's medications (such as diuretics, antidepressants) would be helpful in determining the cause and appropriate treatment.