Fluid and Electrolytes Imbalances for Nursing Students - NCLEX Review

Fluid and Electrolyte Imbalances for Nursing Students

Nurse Sarah reviews the roles, usual blood ranges, causes of imbalances, and common signs and symptoms of six major electrolytes. The central lesson is that electrolyte balance is essential for fluid regulation, nerve signaling, muscle function, bone health, and acid–base balance. When levels become too high or too low, the effects can range from mild symptoms to serious neurological or cardiac problems.

How Fluid and Electrolytes Are Regulated

• Water makes up a large portion of the body and helps transport nutrients and oxygen.
• Electrolytes dissolve in body fluids and carry an electrical charge. They support:
  • Muscle contraction and relaxation
  • Nerve impulses
  • Bone formation
  • Fluid movement across cell membranes
  • Blood acid–base balance
• Electrolytes are obtained mainly through food and drink, absorbed through the gastrointestinal tract, and regulated largely by the kidneys.
• Kidney disease can disrupt electrolyte regulation; severe imbalances may require dialysis.
• Vomiting, diarrhea, sweating, burns, blood loss, gastric suction, diuretics, and hormonal disorders can also alter electrolyte levels.

Sodium

Usual range: 135–145 mEq/L

Sodium is concentrated mainly outside cells and helps regulate fluid balance, muscle contraction, and nerve impulses. Water moves toward areas with more sodium:

• High sodium: Water leaves cells, causing them to shrink.
• Low sodium: Water moves into cells, causing them to swell.

Hyponatremia: Sodium Below 135

Possible causes include:

• Thiazide diuretics, which can increase sodium loss in urine
• Vomiting, diarrhea, sweating, or gastric suction
• Addison’s disease, with low aldosterone and increased sodium loss
• SIADH, which causes water retention and dilutes sodium
• Fluid overload, renal failure, or excess hypotonic fluids

Possible signs and symptoms include seizures or stupor, abdominal cramping, lethargy, diminished tendon reflexes, trouble concentrating, reduced urine output or appetite, orthostatic hypotension, overactive bowel sounds, shallow breathing in severe cases, and muscle spasms.

The video’s memory phrase is “SALT LOSS.”

Hypernatremia: Sodium Above 145

Possible causes include:

• Cushing’s syndrome or Conn’s syndrome, which can promote sodium retention
• Hypertonic or sodium-rich fluids, corticosteroids, or high sodium intake
• Not drinking enough water or losing too much water, such as with diabetes insipidus
• Burns

Possible signs and symptoms include fatigue, restlessness or agitation, confusion, increased reflexes, extreme thirst, decreased urine output, and dry skin or mouth.

The video’s memory phrase is “No fried foods for you.”

Chloride

Usual range: 95–105 mEq/L

Chloride works closely with sodium in fluid balance. It also contributes to acid–base balance and is needed to make hydrochloric acid for digestion. The kidneys regulate chloride, and it is also lost through sweat and gastrointestinal fluids.

Hypochloremia: Low Chloride

Possible causes include:

• Vomiting, gastric suction, or high ileostomy output
• Diuretics, burns, or cystic fibrosis
• Fluid overload or SIADH, which can dilute chloride
• Metabolic alkalosis, in which bicarbonate is elevated

Symptoms are often related to the underlying cause and may overlap with hyponatremia. Possible findings include dehydration, increased heart rate, low blood pressure, fever, vomiting, diarrhea, and lethargy.

Hyperchloremia: High Chloride

Possible causes include:

• Sodium or fluid imbalances, including dehydration
• Diarrhea or other causes of low bicarbonate
• Conn’s syndrome, corticosteroids, or renal problems
• Metabolic acidosis

The video notes that symptoms can resemble those of hypernatremia and acidosis.

Potassium

Usual range: 3.5–5 mEq/L

Potassium is concentrated mainly inside cells. It works with sodium in fluid balance and is especially important for nerve impulses and muscle contraction. Potassium levels have a narrow normal range, and abnormalities can affect heart rhythm.

Hypokalemia: Low Potassium

Possible causes include:

• Loop diuretics, such as furosemide
• Corticosteroids or Cushing’s syndrome
• Excess insulin, which shifts potassium into cells
• Starvation, vomiting, or gastric suction

Possible signs and symptoms include lethargy or confusion, shallow breathing, cardiac dysrhythmias, frequent urination, leg cramps, limp muscles, decreased reflexes, low blood pressure, and a slow heart rate. ECG changes may include ST depression, flattened T waves, and a prominent U wave.

The video’s memory aid is “the seven L’s,” emphasizing that many effects are low or slowed.

Hyperkalemia: High Potassium

Possible causes include:

• Severe burns or tissue breakdown, such as rhabdomyolysis
• Addison’s disease
• Renal failure
• Potassium-sparing diuretics, ACE inhibitors, or NSAIDs

Possible signs and symptoms include muscle weakness, little or no urine, respiratory weakness or failure, reduced cardiac contractility, weak pulse, slow heart rate, muscle twitching or cramping, and rhythm changes. ECG findings may include tall peaked T waves and a prolonged PR interval.

The video uses “MURDER” as a memory aid for the potentially severe effects.

Calcium

Usual range: 8.5–10.5 mg/dL

Calcium supports bones and teeth, muscle and nerve function, and blood clotting. Calcium is absorbed through the gut, with vitamin D helping absorption. Parathyroid hormone (PTH) and calcitonin help regulate blood calcium. Bones can release calcium when blood levels are low, but continued release can weaken bones.

Hypocalcemia: Low Calcium

Possible causes include:

• Low PTH, including after thyroid surgery that affects the parathyroid glands
• Low calcium intake or low vitamin D
• Chronic kidney disease
• Bisphosphonates, aminoglycosides, or some anticonvulsants

Possible signs and symptoms include convulsions, hyperactive reflexes, arrhythmias with a prolonged QT interval, muscle spasms or tetany, and tingling or numbness (paresthesia).

The video’s memory aid is “CRAMPS.”

Two bedside signs discussed are:

• Trousseau sign: Inflation of a blood pressure cuff may trigger hand and wrist flexion.
• Chvostek sign: Tapping near the facial nerve may cause facial muscle twitching.

Hypercalcemia: High Calcium

Possible causes include:

• Overactive parathyroid glands and excess PTH
• Excess vitamin D or calcium supplements
• Cancer that has spread to bone
• Thiazide diuretics or lithium

Possible signs and symptoms include pronounced muscle weakness, a shortened QT interval, absent reflexes, altered mental status, constipation with abdominal distension, and kidney stones.

The video’s memory aid is “WEAK.”

Magnesium

Usual range: 1.5–2.5 mg/dL

Magnesium supports nerve and muscle function, blood pressure regulation, and the sodium–potassium pump. It helps muscles relax and is absorbed mainly in the small intestine. Magnesium imbalances may occur alongside calcium or potassium imbalances.

Hypomagnesemia: Low Magnesium

Possible causes include:

• Low dietary intake or malabsorption
• Other electrolyte imbalances
• Proton pump inhibitors
• Alcohol use disorder

Possible signs and symptoms include hyperactive reflexes, weakness, muscle twitching or tetany, Trousseau and Chvostek signs, arrhythmias including torsades de pointes, and low calcium or potassium.

The video’s memory aid is “TWITCH.”

Hypermagnesemia: High Magnesium

Possible causes include:

• Excess magnesium replacement
• Magnesium sulfate treatment, including in obstetric care
• Renal dysfunction that reduces magnesium excretion

Possible signs and symptoms, especially in severe cases, include lethargy, prolonged PR and QT intervals or a wide QRS complex, absent or diminished reflexes, low blood pressure, arrhythmias, flushing, nausea or vomiting, impaired breathing, and confusion.

The video’s memory aid is “LETHARGIC.” It emphasizes monitoring magnesium levels and reflexes when magnesium sulfate is being administered.

Phosphate

Usual range: 2.5–4.5 mg/dL

Phosphate contributes to bone and tooth formation. It is absorbed in the gut, stored in bones, and excreted by the kidneys. PTH and vitamin D influence phosphate regulation.

Hypophosphatemia: Low Phosphate

Possible causes include:

• Excess use of aluminum-based antacids, which can reduce phosphate absorption
• Starvation or refeeding syndrome
• Overactive parathyroid glands, which increase phosphate loss through the kidneys
• Low vitamin D

Refeeding syndrome can occur after severe starvation: insulin released when feeding resumes can shift phosphate into cells for glucose metabolism and further lower blood phosphate.

Possible signs and symptoms include bone pain, fractures, osteomalacia, impaired growth or bowed legs in children, irritability or confusion, seizures, and destruction of red blood cells that can lead to hemolytic anemia.

The video’s memory aid is “BONE.”

Hyperphosphatemia: High Phosphate

Possible causes include:

• Phosphate-containing laxatives or enemas
• Renal failure
• Excess vitamin D
• Rhabdomyolysis
• Underactive parathyroid glands

Possible signs and symptoms can resemble hypocalcemia, including convulsions, hyperactive reflexes, arrhythmias, muscle spasms, itching, and positive Trousseau or Chvostek signs.

Speakers and Sources Featured

• Nurse Sarah, speaking for RegisteredNurseRN, is the only speaker identified in the subtitles.
• The video also refers viewers to related lessons and a free quiz from RegisteredNurseRN.