Blood serum concentrations are much lowerâonly about 0.4% of the body's potassium is found in blood serum. As noted above, hypokalemia can be caused by the sudden uptake of potassium ions from the bloodstream by muscle or other organs or by an overall depletion of the body's potassium.
Early symptoms of the flu may include conditions such as excessive or sudden fatigue or body aches and chills, according to Healthline. While fatigue can be an early symptom of a cold, in people who have the flu, the fatigue is much worse.
The onset of flu often seems sudden: people describe feeling like they've been hit by a truck.. Common flu symptoms include sudden  onset, fever and chills, cough, muscle and joint pain, headache, fatigue and weakness. Some people also get a stuffy nose and sore throat.