Electrolyte Imbalances Notes

Sodium (Na+)

  • Normal Range: 135-145 mEq/L

  • Abundance: Sodium is the most abundant electrolyte in the extracellular fluid and plays a critical role in maintaining osmotic pressure and fluid balance in the body.

  • Sources: Major dietary sources include table salt (sodium chloride), processed foods, and some natural foods. Sodium is primarily eliminated through kidneys, and its balance is essential for overall health.

  • Functions:

  • Maintains osmolarity and influences cell size, ensuring cells have the right amount of water.

  • Plays a crucial role in water balance since water follows sodium; this is particularly relevant during dehydration or excessive hydration.

  • Essential for the transmission of nerve impulses and muscle contractility, helping with muscle function and overall physical activity.

Hyponatremia

  • Definition: Hyponatremia is defined as a sodium level below 135 mEq/L.

  • Causes:

  • Decreased sodium intake or loss of gastrointestinal fluids (vomiting, sweating, excessive diuresis).

  • Excessive water intake, such as during tap water enemas or excessive hydration practices.

  • Conditions leading to water retention such as congestive heart failure (CHF), cirrhosis, and kidney failure, which prevent sodium from being excreted effectively.

  • Symptoms:

  • Muscle weakness, cramping, and twitching.

  • Neurological symptoms including seizures, flushed skin, dizziness, and profound fatigue.

  • Severe cases may lead to coma and death due to cerebral edema, resulting from hypotonic extracellular fluid that causes water to enter cells, leading to swelling.

Hypernatremia

  • Definition: Hypernatremia is characterized by sodium levels above 145 mEq/L.

  • Causes:

  • Typically arises from the loss of more water than sodium, excessive sodium intake, or inadequate water intake (often seen in elderly or disabled individuals).

  • Symptoms:

  • Notable low urine output, leading to concentrated urine.

  • Neurological symptoms such as restlessness, confusion, irritability, and in severe cases, delirium, coma, or death due to cerebral edema.

Potassium (K+)

  • Normal Range: 3.5-5.0 mEq/L

  • Abundance: Potassium is the major intracellular electrolyte and is primarily obtained through dietary sources, including fruits (like bananas and oranges), vegetables, and nuts.

  • Functions:

  • Essential for maintaining cardiac rhythm and electrical activity of the heart.

  • Vital for nerve impulses and muscle contractions, playing a crucial role in overall muscle function, including heart muscle.

  • Important for glucose utilization in cells and maintenance of acid-base balance.

Hypokalemia

  • Definition: Hypokalemia is defined as potassium levels below 3.5 mEq/L.

  • Causes:

  • Often caused by diuretic use, gastrointestinal losses from vomiting or diarrhea, and dietary deficiency. Conditions like alkalosis can also drive potassium into cells, reducing serum levels.

  • Symptoms:

  • Cardiac arrhythmias, irregular pulse, and notable EKG changes.

  • Symptoms can include weakness, shallow breathing, leg cramps, and lethargy, which may severely impair daily functioning.

Hyperkalemia

  • Definition: Hyperkalemia occurs when potassium levels exceed 5.5 mEq/L.

  • Causes:

  • Commonly due to renal failure, excessive intake through diet or supplementation, or potassium release from cells, particularly during acidosis.

  • Symptoms:

  • Notable EKG changes (such as tall, peaked T-waves), muscle weakness, increased irritability, and gastrointestinal hyperactivity, which can lead to more serious cardiac complications.

Calcium (Ca2+)

  • Normal Range: 9-10.5 mg/dL

  • Abundance: About 99% of calcium is stored in bones, where it is critical for structural support but also plays a vital role in muscle contractions and nerve impulses throughout the body.

  • Regulation: The levels of calcium are tightly regulated by Vitamin D, parathyroid hormone, and calcitonin to maintain bone health and metabolic functions.

Hypocalcemia

  • Definition: Hypocalcemia is defined as calcium levels below 4.5 mg/dL.

  • Causes:

  • Can result from issues related to the parathyroid glands, dietary deficiencies, chronic renal failure, or excessive use of phosphate-based antacids.

  • Symptoms:

  • Symptoms can include muscle spasms or tetany, and increased neurological excitability, which can be assessed using Chvostek's and Trousseau's signs.

Hypercalcemia

  • Definition: Hypercalcemia occurs when calcium levels exceed 5.6 mg/dL.

  • Causes:

  • Commonly caused by hyperparathyroidism, excessive milk intake (milk-alkali syndrome), and prolonged immobilization leading to bone resorption.

  • Symptoms:

  • Symptoms may include depressed central nervous system function, muscle weakness, formation of renal stones, and constipation due to slowed gastrointestinal motility.

Magnesium (Mg2+)

  • Normal Range: 1.5-2.5 mEq/L

  • Functions: Magnesium serves as a cofactor for over 300 enzymatic reactions, regulates calcium and potassium levels, and is crucial for the proper functioning of the central nervous system (CNS).

Hypomagnesemia

  • Definition: Hypomagnesemia is defined as magnesium levels below 1.5 mEq/L.

  • Causes:

  • Can occur due to decreased intake (e.g., poor diet), renal excretion, or gastrointestinal impairment causing malabsorption.

  • Symptoms:

  • Symptoms may include muscle excitability, cardiac dysrhythmias, and shallow respirations where serious cases can affect respiratory function.

Hypermagnesemia

  • Definition: Hypermagnesemia is when magnesium levels exceed 2.5 mEq/L.

  • Causes:

  • Often seen in renal failure or excessive supplementation which can overwhelm renal clearance.

  • Symptoms:

  • Symptoms may include respiratory depression, hypotension, and various central nervous system effects that impair coordination and mental function.

Phosphate (HPO4-3)

  • Normal Range: 2.5-4.5 mg/dL

  • Functions: Phosphate is crucial for maintaining bone health, acts as an acid-base buffer, and is involved in metabolic activities such as energy production (ATP formation).

Hypophosphatemia

  • Causes:

  • Can result from renal failure, excessive dietary phosphate intake, or conditions like hypoparathyroidism.

  • Symptoms:

  • Symptoms can include muscle weakness, joint pain, and confusion, which can significantly impact daily activities.

Hyperphosphatemia

  • Causes:

  • Usually results from dietary excess or urinary losses, often seen in patients with renal failure.

  • Symptoms:

  • Symptoms may include muscle spasms, seizures, and diminished attention span, which can lead to difficulties in concentration and cognitive challenges.

Chloride (Cl-)

  • Normal Range: 95-105 mEq/L

  • Functions: Chloride plays a key role in the regulation of osmotic pressure and is also essential for the formation of hydrochloric acid in the stomach, aiding in digestion.

Hypochloremia & Hyperchloremia

  • Hypochloremia: Often accompanies hyponatremia, indicating a deficiency in chloride levels which may complicate patient management.

  • Hyperchloremia: May arise from bicarbonate loss during metabolic acidosis, further affecting acid-base balance in the body.

Bicarbonate (HCO3-)

  • Normal Range: 22-28 mEq/L

  • Functions: Bicarbonate is a major biochemical base buffer and plays a critical role in regulating the acid-base balance of the body to maintain pH homeostasis.

Regulation

  • The kidneys are responsible for managing bicarbonate levels, which is crucial for maintaining pH balance. Adjustments in bicarbonate reabsorption or excretion directly influence acid-base status in clinical settings.