Which serum laboratory result is the highest priority to report to the healthcare provider?

The highest priority to report to the healthcare provider in this scenario is a sodium level of 120 mEq/L in a patient with small cell lung cancer. This value indicates hyponatremia, which is a critically low level of sodium in the serum. Serum sodium levels below 135 mEq/L can lead to severe neurological symptoms, including confusion, seizures, and even coma, particularly as levels decline further.

In the context of small cell lung cancer, this patient may be experiencing the effects of the syndrome of inappropriate antidiuretic hormone secretion (SIADH), which can cause significant hyponatremia. Because of the potential for rapid clinical deterioration and the serious consequences associated with hyponatremia, this result requires immediate attention.

While the other lab results can indicate significant health concerns—such as the BNP level indicating heart failure and the albumin level reflecting liver function in chronic hepatitis—hyponatremia poses an immediate risk that needs to be addressed promptly to prevent serious complications. The magnesium level of 1.7 mEq/L, while low, does not pose as urgent a risk as the critically low sodium level. Thus, the sodium level holds the highest priority for reporting.