What laboratory test is commonly performed first for diagnosing hyponatremia?

The Basic Metabolic Panel (BMP) is commonly performed first for diagnosing hyponatremia because it includes measurements of sodium levels, along with other electrolytes such as potassium, chloride, bicarbonate, blood urea nitrogen (BUN), and creatinine. When hyponatremia is suspected, evaluating the sodium concentration is crucial, as it directly confirms the presence of the electrolyte imbalance. The BMP is a standard test that provides a quick and comprehensive assessment of various metabolic parameters, thereby serving as an essential initial step in determining the cause and potential implications of hyponatremia.

While other tests like the Complete Blood Count, Coagulation Profile, and Liver Function Tests have their respective roles in evaluating a patient's overall health and can provide important information about other conditions, they do not specifically assess sodium levels and therefore are not the most effective first-line tests when hyponatremia is in question. The BMP's focus on key electrolytes makes it the most relevant and valuable initial test for diagnosing this condition.