Potassium is the major cation of the intracellular fluid of the human body. Is involved in the maintenance of normal water balance, osmotic equilibrium between the cells and the fluid intersticial3 and acid-base balance, determined by the pH of the body. Potassium is also involved in muscle contraction and regulation of neuromuscular activity by participating in the transmission of nerve impulses through the action potentials of the human organism. Due to the nature of their electrostatic properties and chemical potassium ions are larger than sodium ions, so that ion channels and pumps cell membranes can distinguish between the two types of ions actively or passively pump allowing one of these ions pass, while blocking the another.4 Potassium promotes cell growth and partly stored at muscular level, thus if the muscle is being formed (periods of growth and development) an adequate supply potassium is essential. A significant decrease in serum potassium levels (less than 3.5 mEq / L) can cause potentially fatal condition known as hypokalemia, resulting often in situations such as diarrhea, increased diuresis, vomiting and dehydration. Deficiency symptoms include muscle weakness, fatigue, weakness, cramps, gastrointestinal level: ileus, constipation, abnormal electrocardiogram, cardiac arrhythmias, and in severe cases respiratory paralysis and alcalosis.5
Hyperkalemia, or increased potassium levels above 5.5 mEq / L, is one of the most serious electrolyte disturbances may be caused by increased contribution (oral or parenteral: bloodstream), redistribution (intracellular fluid the extracellular) or reduced renal excretion. Generally, clinical manifestations appear with levels greater than 6.5 mEq / L, the main: Cardiovascular changes in the electrocardiogram, ventricular arrhythmias and asystole (cardiac arrest), neuromuscular level: paresthesia, weakness, respiratory failure nausea and gastrointestinal level and vómitos.5
[Edit] absorption, filtration and excretion
Potassium is quickly absorbed from the small intestine. Between 80 and 90% of the potassium intake is excreted in the urine, the rest is lost in the stool. The kidneys maintain normal levels of serum potassium through their ability to filter, absorb and excrete potassium under the influence of the hormone aldosterona.6 Together with sodium, both regulate fluid and electrolyte balance in the body, as are the principal intracellular cation of fluid (potassium) and extracellular (sodium) total body fluid of the organism. The sodium concentration in the plasma is about 145 mEq / L, while potassium is from 3.5 to 4.5 meq / L (in plasma). The plasma is filtered through the glomeruli of the kidneys in huge amounts, about 180 L/día.7 sodium and potassium daily ingested in the diet should be reabsorbed, the sodium should be reabsorbed as necessary to keep the volume plasma osmotic pressure and correctly, while potassium must be reabsorbed to maintain serum concentrations of the cation in 4.8 meq / L (about 190 mg) (6). Sodium pump must always operative to retain sodium. Potassium must sometimes be conserved, but since the plasma potassium amounts are so small, and the potassium concentration at the cellular level is about three times larger, the situation is not so critical for potassium. Since potassium is transported pasivamente8 9 in response to a flow opposite to sodium, urine can never decrease the serum potassium concentrations, except sometimes is observed where active excretion of water. Potassium is secreted and reabsorbed doubly three times before reaching the urine collecting ducts of riñón.10 At this point it is usually reached in plasma concentration. If potassium was removed from the diet, the kidney require a minimum of potassium excretion about 200 mg / day when the serum potassium decline to 3.0 meq / L at one week aproximadamente.11 pump sodium / potassium is a mechanism which can achieve the required concentrations of K + ions and Na + into the cell and out-K + ion concentrations higher inside the cell than outside, to allow the transmission of nerve impulses.
[Edit] Potassium in diet
Adequate intake of potassium can generally be guaranteed by eating a variety of foods containing potassium and deficiency is rare in individuals who eat a balanced diet. Foods that are high sources of potassium include vegetables (broccoli, beets, eggplant and cauliflower) and fruits (bananas, bananas and bone, as grape, apricot, peach, cherry, plum, etc..) potasio.12 are rich in Potassium is the third most abundant mineral in our body. It is involved in the reaction of nerves, muscle movement and healthy maintenance.
Foods that have more potassium are beans or beans that provides 1300 mg of potassium c / 100 g, wheat germ that gives us about 842 mg of potassium c / 100 g, avocado or avocado called in some countries it provides c 600 mg / 100 g, 515 mg soy contributes c / 100 g nuts provide us with 441 mg of potassium c / 100 g, banana or plantain called c provide 396 mg / 100 G.13
Diets high in potassium can reduce the risk of hypertension and potassium deficiency combined with an inadequate thiamine intake has produced deaths in mice experimentales.14
Potassium supplements are used in medicine in most in conjunction with loop diuretics and thiazides, a class of diuretics to decrease sodium levels and body water when this is necessary, but in turn also cause loss of potassium in urine . Individuals nephropathy or renal disease, may suffer adverse health effects from consuming large amounts of potassium. In chronic renal failure, patients are being treated renal dialysis should receive a strict diet in potassium content provided since the kidneys control potassium excretion, serum potassium accumulation by renal failure, can cause problems fatal and fatal cardiac arrhythmia. Acute hyperkalemia may be reduced by treatment with soda oral glucose 15, 16 17 and perspiración.19 hiperventilación18