Electrolyte imbalance

Hypernatremia means that the concentration of sodium in the blood is too high. An individual is considered to be have high sodium at levels above 145 mEq/L of sodium. Hypernatremia is not common in individuals with no other health concerns.[2] Most individuals with this disorder have either experienced loss of water from diarrhea, altered sense of thirst, inability to consume water, inability of kidneys to make concentrated urine, or increased salt intake.[2][8]

There are three types of hypernatremia each with different causes.[2] The first is dehydration along with low total body sodium. This is most commonly caused by heatstroke, burns, extreme sweating, vomiting, and diarrhea.[2] The second is low total body water with normal body sodium. This can be caused by Diabetes insipidus, renal disease, Hypothalamic dysfunction, Sickle cell disease, and certain drugs.[2] The third is increased total body sodium which is caused by increased ingestion, Conn's Disease, or Cushing's syndrome.[2]

Symptoms of hypernatremia may vary depending on type and how quickly the electrolyte disturbance developed.[8] Common symptoms are dehydration, nausea, vomiting, fatigue, weakness, increased thirst, excess urination. Patients may be on medications that caused the imbalance such as Diuretics or Nonsteroidal anti-inflammatory drugs.[8] Some patients may have no obvious symptoms at all.[8]

It is crucial to first assess the stability of the patient. If there are any signs of shock such as Tachycardia or Hypotension, these must be treated immediately with IV saline infusion.[2][8]  Once the patient is stable, it is important to identify the underlying cause of hypernatremia as that may affect the treatment plan.[2][8] The final step in treatment is to calculate the patients free water deficit, and to replace it at a steady rate using a combination of oral or IV fluids.[2][8]  The rate of replacement of fluids varies depending on how long the patient has been hypernatremic. Lowering the sodium level too quickly can cause cerebral edema.[8]

Hyponatremia means that the concentration of sodium in the blood is too low. It is generally defined as a concentration lower than 135 mEq/L.[9] This relatively common electrolyte disorder can indicate the presence of a disease process, but in the hospital setting is more often due to administration of Hypotonic fluids.[10][9] The majority of hospitalized patients only experience mild hyponatremia, with levels above 130 mEq/L. Only 1-4% of patients experience levels lower than 130 mEq/L.[10]

Hyponatremia has many causes including Heart failure, Chronic kidney disease, Liver disease, treatment with Thiazide diurectics, Psychogenic polydipsia, Syndrome of inappropriate antidiuretic hormone secretion.[9] It can also be found in the postoperative state, and in the setting of accidental water intoxication as can be seen with intense exercise. [9] Common causes in pediatric patients may be diarrheal illness, frequent feedings with dilute formula, water intoxication via excessive consumption, and Enemas.[9] Pseudohyponatremia is a false low sodium reading that can be caused by high levels of fats or proteins in the blood.[10][9] Dilutional hyponatremia can happen in diabetics as high glucose levels pull water into the blood stream causing the sodium concentration to be lower.[10][9] Diagnosis of the cause of hyponatremia relies on three factors: volume status, Plasma osmolality, urine sodium levels and Urine osmolality.[10][9]

Many individuals with mild hyponatremia will not experience symptoms. Severity of symptoms is directly correlated with severity of hyponatremia and rapidness of onset.[9] General symptoms include loss of appetite, nausea, vomiting, confusion, agitation, and weakness.[10][9] More concerning symptoms involve the Central nervous system and include seizures, coma, and death due to Brain herniation.[10][9] These usually do not occur until sodium levels fall below 120 mEq/L.[9]

Severity of symptoms, time to onset, volume status, and sodium concentration all dictate appropriate treatment.[10] The patient is immediately treated with Hypertonic saline where the sodium level is <120 mEq/L, the patient is experiencing severe neurological symptoms, or the onset was rapid.[10] In non-emergent situations, it is important to correct the sodium slowly to minimize risk of Osmotic demyelination syndrome.[10][9] Method of correction depends on the underlying cause of the imbalance. If a patient has low total body water and low sodium they are typically given an IV fluid called Normal saline.[9] If a patient has high total body water due to heart failure or kidney disease, they may be placed on fluid and salt restriction or treated with a Loop diuretic.[9] If a patient has a normal volume of total body water, they are placed on fluid restriction alone.[9]

Hyperkalemia means the concentration of potassium in the blood is too high. This occurs when the concentration of potassium is >5 mEq/L.[9][10] It can lead to cardiac Arrhythmias and even death.[9] As such it is considered to be the most dangerous electrolyte disturbance.[9]

Hyperkalemia is typically caused by decreased excretion by the kidneys, shift of potassium to the extracellular space, or increased consumption of potassium rich foods in patients with kidney failure.[9] The most common cause of hyperkalemia is lab error due to potassium released as blood cells from the sample break down.[10] Other common causes are kidney disease, cell death, Acidosis, and drugs that affect kidney function.[9]

Part of the danger of hyperkalemia is that it is often asymptomatic, and only detected during normal lab work done by primary care physicians.[9] As potassium levels get higher, individuals may begin to experience nausea, vomiting, and diarrhea.[9] Patients with severe hyperkalemia, defined by levels above 7 mEq/L, may experience muscle cramps, numbness, tingling, absence of reflexes, and paralysis.[9][10] Patients may experience arrhythmias that can result in death.[9][10]

There are three mainstays of treatment of hyperkalemia. These are stabilization of cardiac cells, shift of potassium into the cells, and removal of potassium from the body.[9][10] Stabilization of cardiac muscle cells is done by administering calcium intravenously.[9] Shift of potassium into the cells is done using both insulin and albuterol inhalers.[9] Excretion of potassium from the body is done using either hemodialysis, loop diuretics, or a resin that causes potassium to be excreted in the fecal matter.[9]

The most common electrolyte disturbance, hypokalemia means that the concentration of potassium is <3.5 mEq/L.[9] It often occurs concurrently with low magnesium levels.[9]

Low potassium is caused by increased excretion of potassium, decreased consumption of potassium rich foods, movement of potassium into the cells, or certain endocrine diseases.[9] Excretion is the most common cause of hypokalemia and can be caused by diuretic use, metabolic acidosis, diabetic ketoacidosis, hyperaldosteronism, and renal tubular acidosis.[9] Potassium can also be lost through vomiting and diarrhea.[10]

Hypokalemia is often asymptomatic, and symptoms may not appear until potassium concentration is <2.5 mEq/L.[10] Typical symptoms consist of muscle weakness and cramping. Low potassium can also cause cardiac arrythmias.[9][10]

Hypokalemia is treated by replacing the body's potassium. This can occur either orally or intravenously.[9][10] Because low potassium is usually accompanied by low magnesium, patients are often given magnesium alongside potassium.[10]

Hypercalcemia is when the concentration of calcium in the blood is too high. This occurs above 10.5 mEq/dL.[9] Very high levels of calcium in the blood can cause severe issues.[9]

The most common causes of hypercalcemia are certain types of cancer, hyperparathyroidism, hyperthyroidism, pheochromocytoma, excessive ingestion of vitamin D, sarcoidosis, and tuberculosis.[9] Hyperparathyroidism and malignancy are the predominate causes.[10] It can also be caused by muscle cell breakdown, prolonged immobilization, dehydration.[9]

The predominate symptoms of hypercalcemia are abdominal pain, constipation, kidney stones, extreme thirst, excessive urination, nausea and vomiting.[9][10] In severe cases where the calcium concentration is >14 mEq/dL, individuals may experience confusion, altered mental status, coma, and seizure.[9][10]

Primary treatment of hypercalcemia consists of administering IV fluids.[9] If the hypercalcemia is severe and/or associated with cancer, it may be treated with bisphosphonates.[9][10] For very severe cases, hemodialysis may be considered for rapid removal of calcium from the blood.[9][10]

Hypoparathyroidism and vitamin D deficiency are common causes of hypocalcemia.[9] It can also be caused by malnutrition, blood transfusion, ethylene glycol intoxication, and pancreatitis.[9]

Neurological and cardiovascular symptoms are the most common manifestations of hypocalcemia.[9][10] Patients may experience muscle cramping or twitching, and numbness around the mouth and fingers. They may also have shortness of breath, low blood pressure, and cardiac arrhythmias.[9]

Patients with hypocalcemia may be treated with either oral or IV calcium.[9] Typically, IV calcium is reserved for patients with severe hypocalcemia.[9][10] It is also important to check magnesium levels in patients with hypocalcemia and to replace magnesium if it is low.[10]