Disease Correlation

Electrolyte imbalances are commonly encountered in clinical practice and can be indicative of a wide range of underlying disease states. Accurate assessment of electrolyte levels, along with consideration of the patient’s clinical presentation and medical history, is crucial for proper diagnosis and management

• Sodium Imbalances
• Potassium Imbalances
• Chloride Imbalances
• Calcium Imbalances
• Magnesium Imbalances
• Phosphorus Imbalances

Sodium Imbalances

• Hyponatremia: Serum Sodium < 136 mmol/L
  • Hypovolemic Hyponatremia: Both total body water (TBW) and total body sodium (TBNa) are decreased, but TBNa is decreased to a greater extent than TBW
    • Causes: Diuretic use (thiazides), vomiting, diarrhea, third spacing
  • Euvolemic Hyponatremia: TBW is increased, while TBNa remains normal
    • Causes: Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH), hypothyroidism, glucocorticoid deficiency, psychogenic polydipsia
  • Hypervolemic Hyponatremia: Both TBW and TBNa are increased, but TBW is increased to a greater extent than TBNa
    • Causes: Heart failure, cirrhosis, nephrotic syndrome
• Disease State Correlation
  • Congestive Heart Failure (CHF): Reduced cardiac output leads to activation of the renin-angiotensin-aldosterone system (RAAS) and increased water retention, resulting in hypervolemic hyponatremia
  • Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH): Excessive ADH secretion leads to increased water reabsorption in the kidneys, resulting in euvolemic hyponatremia
  • Chronic Kidney Disease (CKD): Impaired sodium and water excretion by the kidneys can lead to hypervolemic hyponatremia
  • Diarrhea: Loss of sodium-rich intestinal secretions can lead to hypovolemic hyponatremia
• Hypernatremia: Serum Sodium > 145 mmol/L
  • Hypovolemic Hypernatremia: Both TBW and TBNa are decreased, but TBW is decreased to a greater extent than TBNa
    • Causes: Diuretics, diarrhea, vomiting, sweating
  • Euvolemic Hypernatremia: TBW is decreased, while TBNa remains normal
    • Causes: Diabetes Insipidus (DI), decreased water intake
  • Hypervolemic Hypernatremia: Both TBW and TBNa are increased, but TBNa is increased to a greater extent than TBW
    • Causes: Sodium bicarbonate administration, hypertonic saline infusion
• Disease State Correlation
  • Diabetes Insipidus (DI): Deficiency of ADH (central DI) or resistance to ADH (nephrogenic DI) leads to excessive water loss and hypernatremia
  • Dehydration: Insufficient water intake or excessive water loss leads to hypernatremia
  • Hypertonic Saline Infusion: Administration of hypertonic saline can lead to hypervolemic hypernatremia
  • Cushing’s Syndrome: Excessive cortisol levels can lead to an increase in sodium levels and decrease potassium levels

Potassium Imbalances

• Hypokalemia: Serum Potassium < 3.5 mmol/L
  • Decreased Intake: Poor dietary intake, starvation
  • Increased Loss: Diuretics (loop and thiazide), vomiting, diarrhea
  • Cellular Shift: Insulin administration, alkalosis, beta-adrenergic agonists
• Disease State Correlation
  • Diuretic Use: Loop and thiazide diuretics increase potassium excretion in the kidneys, leading to hypokalemia
  • Gastrointestinal Losses: Vomiting and diarrhea lead to potassium loss and hypokalemia
  • Insulin Administration: Insulin promotes potassium uptake into cells, leading to hypokalemia
  • Metabolic Alkalosis: Alkalosis promotes cellular uptake of potassium, leading to hypokalemia
• Hyperkalemia: Serum Potassium > 5.1 mmol/L
  • Decreased Excretion: Kidney failure, hypoaldosteronism, potassium-sparing diuretics
  • Cellular Release: Tissue damage, hemolysis, acidosis, insulin deficiency
  • Increased Intake: Excessive potassium supplementation
• Disease State Correlation
  • Kidney Failure: Impaired potassium excretion leads to hyperkalemia
  • Hypoaldosteronism: Deficiency of aldosterone leads to decreased potassium excretion and hyperkalemia
  • Potassium-Sparing Diuretics: These diuretics block sodium reabsorption in the kidneys, leading to increased potassium retention and hyperkalemia
  • Acidosis: Acidosis promotes cellular release of potassium, leading to hyperkalemia
  • Rhabdomyolysis: The breakdown of muscle tissue releases potassium into the bloodstream, leading to hyperkalemia

Chloride Imbalances

• Hypochloremia: Serum Chloride < 98 mmol/L
  • Increased Loss: Vomiting, nasogastric suctioning, diuretics
  • Increased Bicarbonate: Metabolic alkalosis
  • Water Retention: SIADH, heart failure
• Disease State Correlation
  • Vomiting: Loss of hydrochloric acid (HCl) in gastric secretions leads to hypochloremia and metabolic alkalosis
  • Diuretics: Thiazide diuretics increase chloride excretion in the kidneys, leading to hypochloremia
  • SIADH: Excessive water retention dilutes the chloride concentration in the blood, leading to hypochloremia
• Hyperchloremia: Serum Chloride > 107 mmol/L
  • Chloride Excess: Excessive saline infusion
  • Bicarbonate Loss: Diarrhea, renal tubular acidosis
  • Dehydration: Water deficit
• Disease State Correlation
  • Excessive Saline Infusion: Administration of large volumes of saline can lead to hyperchloremia
  • Diarrhea: Loss of bicarbonate-rich intestinal secretions leads to hyperchloremic metabolic acidosis
  • Renal Tubular Acidosis (RTA): Impaired bicarbonate reabsorption by the kidneys leads to hyperchloremic metabolic acidosis
  • Dehydration: Loss of water leads to increased chloride concentration and hyperchloremia

Calcium Imbalances

• Hypocalcemia: Serum Calcium < 8.6 mg/dL
  • Decreased Intake: Poor dietary intake
  • Vitamin D Deficiency: Leads to decreased calcium absorption
  • Hypoparathyroidism: Decreased parathyroid hormone
• Disease State Correlation
  • Hypoparathyroidism: Decreased PTH production leads to decreased bone resorption and decreased calcium reabsorption in the kidneys
  • Vitamin D Deficiency: Impaired calcium absorption in the intestine leads to hypocalcemia
  • Chronic Kidney Disease (CKD): Decreased kidney function leads to decreased vitamin D activation, increased phosphate levels, and hypocalcemia
• Hypercalcemia: Serum Calcium > 10.2 mg/dL
  • Malignancy: Leads to increased bone resorption due to the release of chemicals that affect serum albumin
  • Hyperparathyroidism: Increased calcium absorption and calcium release by bones

Magnesium Imbalances

• Hypomagnesemia: Serum Magnesium < 1.7 mg/dL
  • Decreased Intake: Poor dietary intake
  • Losses by the Kidneys: Magnesium is depleted
  • Renal Loss: Alcohol and diabetes can affect magnesium balances
• Disease State Correlation
  • Alcoholism: Poor dietary intake, impaired magnesium absorption, and increased urinary magnesium excretion
  • Diabetes Mellitus: Increased urinary magnesium excretion due to osmotic diuresis
  • Diarrhea: Large amounts of magnesium may be lost
• Hypermagnesemia: Serum Magnesium > 2.2 mg/dL
  • Increased intake: In conjunction with kidney function
  • Decreased Kidney Output: Inability for magnesium to release

Phosphorus Imbalances

• Hypophosphatemia: Serum Phosphorus < 2.5 mg/dL
  • Decreased Intake: Poor dietary intake
  • Shift of phosphate to the intracellular space
  • Kidney Issues: Excessive losses of phosphorus can occur due to impaired kidney reabsoption
• Disease State Correlation
  • Refeeding Syndrome: Carbohydrate reintroduction in malnourished patients can lead to a rapid shift of phosphorus into cells, resulting in hypophosphatemia
  • Alcohol Use Disorder: Inadequate dietary intake
  • Hyperparathyroidism: Increased urinary phosphate excretion
  • Use of Phosphate-Binding Antacids: Reduces intestinal phosphate absorption
• Hyperphosphatemia: Serum Phosphorus > 4.5 mg/dL
  • Decreased excretion via the kidneys
  • Shift of Phosphate to the extracellular space
  • Increased Phosphorus Intake: Can occur from increased phosphorus absorption
• Disease State Correlation
  • Kidney Failure: Decreased phosphate excretion leads to hyperphosphatemia
  • Hypoparathyroidism: Decreased parathyroid hormone leads to decreased phosphate excretion
  • Tumor Lysis Syndrome: Rapid cell breakdown releases phosphate into the bloodstream

Trace Elements

• Iron (Fe)
  • Iron Deficiency Anemia: Microcytic, hypochromic anemia, fatigue, weakness, pallor, low serum iron, low ferritin, high TIBC
    • Poor dietary intake, impaired absorption, or chronic blood loss
  • Hemochromatosis: Fatigue, joint pain, abdominal pain, elevated serum iron, elevated ferritin, elevated transferrin saturation
    • Genetic disorder leading to excessive iron absorption
• Copper (Cu)
  • Wilson’s Disease: Liver disease, neurological symptoms, Kayser-Fleischer rings in the eyes, low serum ceruloplasmin, elevated urine copper
    • Genetic disorder leading to copper accumulation in the liver, brain, and other organs
• Iodine (I)
  • Iodine Deficiency: Goiter, hypothyroidism, developmental abnormalities
    • Inadequate dietary iodine intake

Summary Table of Key Findings

Disorder	Na	K	Cl	Ca	Mg	P	Fe	TIBC
CHF	↓	N	↓	N	N	N	N	N
Diabetes Insipidus	↑	N	↑	N	N	N	N	N
Vomiting	↓	↓	↓	N	N	N	N	N
Diuretics	↓	↓/↑	↓/↑	↑	↓	↓/↑	N	N
Alcoholism	N	N	N	N	↓	↓	N	N
Chronic Kidney Disease	N	↑/N	N/↑	↓/N	↑	↑	N/↓	N/↓
Hyperparathyroidism	N	N	N	↑	↑	↓	N	N

• ↑ = Increased, ↓ = Decreased, N = Normal

Key Terms

• Electrolyte: A substance that produces an electrically conducting solution when dissolved in a polar solvent, such as water
• Ion: An atom or molecule with a net electric charge due to the loss or gain of electrons
• Cation: A positively charged ion
• Anion: A negatively charged ion
• mmol/L: A concentration unit, expressing the amount of a substance in a solution
• mg/dL: A concentration unit, expressing the amount of a substance in a solution
• μg/dL: A concentration unit, expressing the amount of a substance in a solution
• μmol/L: A concentration unit, expressing the amount of a substance in a solution
• mg/L: A concentration unit, expressing the amount of a substance in a solution
• Nephrogenic Diabetes Insipidus: A disease in which the kidneys are unable to concentrate urine
• Heart Failure: A chronic progressive condition in which the heart muscle is unable to pump enough blood through to meet the body’s needs for blood and oxygen
• Hypoparathyroidism: A disease in which the parathyroid glands in the neck do not produce enough parathyroid hormone (PTH)
• Hormone: A regulatory substance produced in an organism and transported in tissue fluids such as blood or sap to stimulate specific cells or tissues into action
• Acrodermatitis Enteropathica: A genetic disorder that affects zinc absorption, leading to skin lesions, diarrhea, and growth retardation
• Wilson’s Disease: A genetic disorder that causes copper to accumulate in the liver, brain, and other organs, leading to liver disease and neurological symptoms
• SIADH: Syndrome of Inappropriate Antidiuretic Hormone Secretion, a condition in which the body retains too much water
• In Vitro: Taking place in a test tube, culture dish, or elsewhere outside a living organism
• In Vivo: Occurring within a living organism
• Homeostasis: The process by which organisms maintain a relatively stable internal environment
• Hypovolemia: The medical term for a decrease in blood volume which results in decreased oxygen delivery to the body
• Transfusion: The process of transferring blood or blood products from one person to another
• Lethargy: A state of tiredness, weariness, fatigue, or lack of energy
• Ischemia: An inadequate blood supply to an organ or part of the body
• Hypoxia: An inadequate oxygen supply to the cells and tissues of the body
• Hypercapnia: The presence of abnormally high levels of carbon dioxide in the blood
• Hypoventilation: The state in which a reduced amount of air enters the lungs
• Hyperventilation: The state of breathing too fast or too deeply
• Paresthesias: An abnormal sensation, typically tingling or pricking (“pins and needles”), caused chiefly by pressure on or damage to peripheral nerves
• Carpopedal Spasm: Cramps in the hands and feet
• Hemodialysis: A way to remove waste products from the blood when the kidneys can no longer function properly
• Anabolic: Pertaining to or promoting the synthesis of complex molecules from simpler ones