What causes high potassium and sodium levels in blood?

Q: The potassium and sodium levels in my blood are high. What food should I avoid to lower it down? How should I manage it? Sodium: -149 mmol/L (normal value-135-145); Potassium - 6.7 mmol/L (normal value-3.5-5.5). Please advise.

A:Potassium (K+) and sodium (Na+) are major ions of the body. Virtually all (98%) of K+ is found within cells and the concentration difference within and outside the cells determines the cellular membrane potential. Even minor changes in the blood level of K+ can have profound effect on the heart, nerves and muscles. Potassium levels are maintained by a balance between oral intake and its excretion by the kidneys. Its normal blood level is 3.5-5.0 mEq/L. Water and Na+ is regulated by the balance between water intake and the combined water loss from kidneys, lungs, skin, and intestine with the kidneys playing a major role by adjusting urine concentration to match salt intake and loss. Its levels are tightly controlled by regulation of urine concentration and our thirst response. Hypernatremia (increased blood level of sodium) results from disequilibrium of one or both of these balances. Most commonly, the disorder is caused by a relative free water loss, although it can be caused by salt loading. It is defined as a serum sodium level >145 mEq/L and is rather rare. When hypernatremia does occur, it is associated with a high mortality rate (>50% in most studies). It may be due to a) derangement of the thirst response or individuals who are unable to respond to thirst (infants, psychiatric patients and elderly); b) diseases affecting kidney or those affecting its neuro-hormonal control (diabetes insipidus or c) conditions causing loss of free water. Hyperkalemia (raised blood levels of potassium) is a potentially life-threatening condition, which can lead to sudden death from cardiac arrhythmias and is often difficult to diagnose because of absence of distinctive signs and symptoms. Hyperkalemia is defined as a potassium level greater than 5.5 mEq/L and can be mild (5.5 - 6.0 mEq/L), moderate (6.1 - 7.0 mEq/L) or severe (>7.0 mEq/L). It may be caused by a) Reduced or impaired potassium excretion (acute or chronic renal failure, potassium-sparing diuretics, urinary obstruction, Addison disease); b) Use of potassium supplements, severe muscle injury, hemolysis, burns, blood transfusions; c) Acidosis or drugs. Factitious elevation or pseudohyperkalemia should always be excluded and this may be caused by improper blood collection, laboratory error, or high white blood cell or platelet counts. Please consult a physician and have the tests repeated in a reputed lab before anything can be advised.