What complication is most associated with excess potassium in a neonate?

Excess potassium in a neonate can lead to notable cardiac changes, one of which is the presence of peaked T waves on an electrocardiogram (ECG). Elevated potassium levels, or hyperkalemia, can significantly impact cardiac muscle function and electrical conduction. The T wave changes are a direct consequence of altered repolarization of cardiac myocytes, which manifests as the characteristic peaked appearance on the ECG.

In neonates, monitoring electrolyte levels is crucial since they have a limited physiological reserve and may not tolerate imbalances well. Hyperkalemia can also lead to serious arrhythmias, muscle weakness, and potential cardiovascular collapse if not addressed promptly, which is why identifying peaked T waves is vital for early intervention.

Other options may relate to potassium levels but do not reflect the immediate and specific complications associated with hyperkalemia as clearly as peaked T waves do. In this case, the peaked T wave is a direct reflection of the hyperkalemic state and is critical for the clinical management of affected neonates.