Cause | Underlying condition |
Hypoproteinemia | Cirrhosis Gastroenteropathy Malnutrition Nephrotic syndrome |
Increased endothelial permeability | Allergic or immunologic reactions Burns Inflammation Trauma |
Increased hydrostatic pressure | Cirrhosis Constrictive pericarditis Heart failure Venous thrombosis |
Lymphatic obstruction | Cancer Inflammatory scarring Radiation |
Sodium retention | Excessive salt intake Increased tubular reabsorption of sodium Reduced renal perfusion |
Blood pressure | Fluid and electrolyte status |
Normal | ♦ Hemodynamic stability ♦ Initial hemodynamic instability |
Hypotension | ♦ Fluid volume deficit ♦ Potassium imbalance ♦ Calcium imbalance ♦ Magnesium imbalance ♦ Acidosis |
Hypertension | ♦ Fluid volume excess ♦ Hypernatremia |
oliguria. Blood pressure may be increased or decreased. (See Fluid and electrolyte implications of blood pressure findings.) The GI tract is particularly susceptible to electrolyte imbalance:
Electrolyte imbalance | Signs and symptoms | Diagnostic test results |
Hyponatremia | ♦ Muscle twitching and weakness due to osmotic swelling of cells ♦ Lethargy, confusion, seizures, and coma due to altered neurotransmission ♦ Hypotension and tachycardia due to decreased extracellular circulating volume ♦ Nausea, vomiting, and abdominal cramps due to edema affecting receptors in the brain or vomiting center of the brain stem ♦ Oliguria or anuria due to renal dysfunction | ♦ Serum sodium < 135 mEq/L ♦ Decreased urine specific gravity ♦ Decreased serum osmolality ♦ Urine sodium > 100 mEq/24 hours ♦ Increased red blood cell count |
Hypernatremia | ♦ Agitation, restlessness, fever, and decreased level of consciousness due to altered cellular metabolism ♦ Hypertension, tachycardia, pitting edema, and excessive weight gain due to water shift from intracellular to extracellular fluid ♦ Thirst, increased viscosity of saliva, rough tongue due to fluid shift ♦ Dyspnea, respiratory arrest, and death from dramatic increase in osmotic pressure | ♦ Serum sodium > 145 mEq/L ♦ Urine sodium < 40 mEq/24 hours ♦ High serum osmolality |
Hypokalemia | ♦ Dizziness, hypotension, arrhythmias, electrocardiogram (ECG) changes, and cardiac arrest due to changes in membrane excitability ♦ Nausea, vomiting, anorexia, diarrhea, decreased peristalsis, and abdominal distention due to decreased bowel motility ♦ Muscle weakness, fatigue, and leg cramps due to decreased neuromuscular excitability | ♦ Serum potassium < 3.5 mEq/L ♦ Coexisting low serum calcium and magnesium levels not responsive to treatment for hypokalemia usually suggest hypomagnesemia ♦ Metabolic alkalosis ♦ ECG changes include flattened T waves, elevated U waves, depressed ST segment |
Hyperkalemia | ♦ Tachycardia changing to bradycardia, ECG changes, and cardiac arrest due to hypopolarization and alterations in repolarization ♦ Nausea, diarrhea, and abdominal cramps due to smooth-muscle hyperactivity in the GI tract ♦ Muscle weakness and flaccid paralysis due to inactivation of membrane sodium channels | ♦ Serum potassium > 5 mEq/L ♦ Metabolic acidosis ♦ ECG changes include tented and elevated T waves, widened QRS complex, prolonged PR interval, flattened or absent P waves, depressed ST segment |
Hypochloremia | ♦ Muscle hypertonicity and tetany due to increased neuromuscular irritability ♦ Shallow, depressed breathing as the body attempts to compensate for alkalosis ♦ Usually associated with hyponatremia and its characteristic symptoms, such as muscle weakness and twitching | ♦ Serum chloride < 98 mEq/L ♦ Serum pH > 7.45 (supportive value) ♦ Serum carbon dioxide (CO2) > 32 mEq/L (supportive value) |
Hyperchloremia | ♦ Major signs and symptoms are due to metabolic acidosis ♦ Deep, rapid breathing ♦ Weakness ♦ Diminished cognitive ability, possibly leading to coma | ♦ Serum chloride > 108 mEq/L ♦ Serum pH < 7.35, serum CO2 < 22 mEq/L (supportive values) |
Hypocalcemia | ♦ Anxiety, irritability, twitching around the mouth, laryngospasm, seizures, positive Chvostek’s and Trousseau’s signs due to enhanced neuromuscular irritability ♦ Hypotension and arrhythmias due to decreased calcium influx | ♦ Serum calcium < 8.5 mg/dl ♦ Low platelet count ♦ ECG shows lengthened QT interval, prolonged ST segment, arrhythmias ♦ Possible changes in serum protein because half of serum calcium is bound to albumin |
Hypercalcemia | ♦ Drowsiness, lethargy, headaches, irritability, confusion, depression, or apathy due to decreased neuromuscular irritability (increased threshold) ♦ Weakness and muscle flaccidity due to depressed neuromuscular irritability and release of acetylcholine at the myoneural junction ♦ Bone pain and pathological fractures due to calcium loss from bones ♦ Heart block due to decreased neuromuscular irritability ♦ Anorexia, nausea, vomiting, constipation, and dehydration due to hyperosmolarity ♦ Flank pain due to kidney stone formation | ♦ Serum calcium > 10.5 mg/dl ♦ ECG shows signs of heart block and shortened QT interval ♦ Azotemia ♦ Decreased parathyroid hormone level ♦ Sulkowitch urine test shows increased calcium precipitation |
Hypomagnesemia | ♦ Nearly always coexists with hypokalemia and hypocalcemia ♦ Hyperirritability, tetany, leg and foot cramps, positive Chvostek’s and Trousseau’s signs, confusion, delusions, and seizures due to alteration in neuromuscular transmission ♦ Arrhythmias, vasodilation, and hypotension due to enhanced inward sodium current or concurrent effects of calcium and potassium imbalance | ♦ Serum magnesium < 1.5 mEq/L ♦ Coexisting low serum potassium and calcium levels |
Hypermagnesemia | ♦ Hypermagnesemia is uncommon, caused by decreased renal excretion (renal failure) or increased intake of magnesium ♦ Diminished reflexes, muscle weakness to flaccid paralysis due to suppression of acetylcholine release at the myoneural junction, blocking neuromuscular transmission and reducing cell excitablity ♦ Respiratory distress secondary to respiratory muscle paralysis ♦ Heart block, bradycardia due to decreased inward sodium current ♦ Hypotension due to relaxation of vascular smooth muscle and reduction of vascular resistance by displacing calcium from the vascular wall surface | ♦ Serum magnesium > 2.5 mEq/L ♦ Coexisting elevated potassium and calcium levels |
Hypophosphatemia | ♦ Muscle weakness, tremor, and paresthesia due to deficiency of adenosine triphosphate ♦ Peripheral hypoxia due to 2,3-diphosphoglycerate deficiency | ♦ Serum phosphate < 2.5 mg/dl ♦ Urine phosphate > 1.3 g/24 hours |
Hyperphosphatemia | ♦ Usually asymptomatic unless leading to hypocalcemia, with tetany and seizures | ♦ Serum phosphate > 4.5 mg/dl ♦ Serum calcium < 9 mg/dl ♦ Urine phosphorus < 0.9 g/24 hours |