What do abnormal serum osmolality results suggest about a patient with an elevated osmolal gap?

An elevated osmolal gap indicates that there are unmeasured osmotically active substances present in the serum. In clinical practice, this often suggests the presence of substances such as drugs or alcohol that can influence serum osmolality but are not accounted for in the routine measurements of electrolytes or glucose.

In cases of drug or alcohol intoxication, particularly with substances such as methanol or ethylene glycol, these compounds can lead to significant increases in serum osmolality, resulting in a higher osmolal gap. This finding necessitates further investigation and potential treatment, as these substances can have serious toxic effects on the body.

Other options may not align with the interpretation of an elevated osmolal gap. For instance, laboratory errors or specimen misidentification typically would not result in a systemic increase in osmolality unless there was a consistent error across multiple tests, which is uncommon. Successful rehydration of a patient is also less likely to cause an elevated osmolal gap, as rehydration generally leads to a dilution of serum osmolality rather than an increase. Therefore, when evaluating abnormal serum osmolality with an elevated osmolal gap, drug or alcohol intoxication stands out as the most plausible explanation.