The kidneys perform the vital job of maintaining the body’s acid-alkaline balance, called its pH. Blood pH needs to be held in a narrow range, slightly alkaline but close to neutral. The kidneys do this job by providing the blood with a buffer solution that compensates for any rise or fall in the level of acidity or alkalinity caused by diet or stress. This buffer solution contains fluids as well as vital salts, called electrolytes, including sodium, potassium and bicarbonate. In a sense body is like a car battery, which also depends on electrolytes to produce electrical current. But a battery is static while body is dynamic. Electrolyte levels of the body are continually adjusted as needed to maintain pH.
Hyperkalemia (Potassium imbalance): The kidneys are responsible for the excretion of potassium from the body and alter the extent of potassium excretion according to the current concentration in the blood. An individual with acute kidney failure may not be able to excrete as much potassium as usual, leading to excess potassium known as hyperkalemia. Hyperkalemia is associated with symptoms such as:
- Abdominal cramping
- Fatigue
- Muscle weakness
- Paralysis
- Cardiac arrest
Hypernatremia (Sodium imbalance): The concentration of sodium is essential for maintaining fluid and acid-base balance and for neuromuscular function. Healthy kidneys alter the excretion of sodium in the urine to prevent hypernatremia. An individual with acute kidney failure may not be able to excrete as much sodium as usual, thus causing hypernatremia, which is associated with symptoms such as:
- Disorientation
- Muscular twitching
- Hypertension
- Weakness
Hypermagnesemia (Magnesium imbalance): Likewise, renal failure can also commonly cause an increase in the levels of magnesium in the blood, due to insufficient excretion of the electrolyte. Hypermagnesemia is associated with symptoms such as:
- Hypotension
- Reduced heart rate
- Cardiac arrest
Hypocalcemia – (phosphorus and calcium imbalance): There is a reciprocal relationship between phosphorus and calcium, and the levels of both of these electrolytes can be affected by kidney failure. It can lead to retention of phosphorus and a reduction in the levels of calcium in the blood. Hypocalcemia is associated with symptoms such as:
- Muscle spasms
- Seizures
- Arrhythmias
- Demineralization of bones
- Cardiac failure
Electrolyte disturbance: The role of the kidneys in maintaining the balance of fluid and electrolytes in the blood becomes clear when considering the outcomes on electrolytes in patients with acute renal failure. The levels of electrolytes such as potassium, sodium, magnesium, phosphorus, and calcium can all be affected and lead to a range of symptoms. Fortunately, if the cause of acute kidney failure is reverse and normal renal function returns, the electrolyte disturbances and related symptoms should improve.
Metabolic Acidosis: Metabolic acidosis is a condition that occurs when the body produces excessive quantities of acid (pH balance <7.35), low bicarbonate (< 22mEq/L), and low hydrogen concentration. It is reflected by breathing trouble, fall in blood pressure, decreased cardiac function, headache and confusion. Treatment of chronic kidney disease associated metabolic acidosis with oral alkali to achieve a normal serum bicarbonate level has been shown in observational studies to slow chronic kidney disease progression. When the bicarbonate level is less than 22 mmol/L as mentioned above, sodium bicarbonate (650mg) may be prescribed 3 times daily. This dose corresponds to approximately 23 mEq daily of sodium and bicarbonate. If this does not result in a serum bicarbonate level of at least 22 mmol/L, a nephrology referral is indicated.
The following table gives the normal range of electrolytes in the body, causes of elevation and decline.
