Sodium
From Gomerpedia
Sodium is an electrolyte symbolized by the letters Na. The reason why sodium is so critically important is that it is one of the few words and one of the few electrolytes that rhymes with the word podium and actually rhymes well (unlike cranium, which is a bit of a stretch). Yes, hyponatremia and hypernatremia are somewhat important, but if you're freestylin' and you use the word podium, and sodium was never an electrolyte?? Man... That'd be the worst.