Calcium (Ca2+)
8.5-10.5 mg/dL |
Hypocalcemia
- Signs and symptoms
- Tetany (neuromuscular irritability) is the hallmark symptom (may include paresthesia, bronchospasm, laryngospasm, carpopedal spasm [Trousseau’s sign], Chvostek’s sign [facial muscle contractions elicited by tapping facial nerve on ipsilateral side], tingling sensations of the fingers, mouth, and feet, increased deep tendon reflexes [DTRs], generalized seizures).
- Psychiatric manifestations such as emotional instability, depression, anxiety, hallucinations and psychosis.
- ECG changes may include prolonged QT interval and arrhythmias.
- Papilledema with or without intracranial hypertension.
- Anxiety, depression, fatigue.
- Can also be asymptomatic.
- Implement seizure precautions and close monitoring for cardiac arrhythmias and respiratory depression.
- Treatment: initiate intravenous calcium repletion
Hypercalcemia
- Signs and symptoms
- Lethargy, confusion, nausea, vomiting, anorexia, constipation, muscle weakness, depressed DTRs, polyuria, polydipsia, dehydration
- Severe hypercalcemia can provoke supraventricular or ventricular arrhythmias. Monitor cardiac rate and rhythm.
- Increase mobilization, provide adequate hydration either with IV fluids or encouragement of oral intake.
- Watch for digitalis toxicity.
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Chloride (Cl-)
97-107 mEq/L |
Hypochloremia
- Signs and symptoms
- Muscle spasms, alkalosis, and depressed respirations
- May be precipitated or exacerbated by GI losses (vomiting, diarrhea).
Hyperchloremia
- Monitor for metabolic acidosis.
- Associated with large volume 0.9% normal saline resuscitation.
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Magnesium (Mg2+)
1.8-3 mg/dL |
Hypomagnesemia
- Signs and symptoms
- Cardiac/ventricular arrhythmias (ventricular arrythmias (torsades de pointes) and atrial fibrillation), tetany, tremor, weakness, apathy, delirium, seizures, and coma
- Risk factors: chronic diarrhea, PPI use, alcoholism, diuretic use
- Monitor cardiac rate and rhythm.
- Monitor for digitalis toxicity.
- Often associated with hypokalemia. Treat both simultaneously.
Hypermagnesemia
- Signs and symptoms
- Early symptoms: nausea, vomiting, flushing
- Cardiac manifestations: hypotension, bradycardia, complete heart block, cardiac arrest
- Neurologic manifestations: lethargy/somnolence, decreased DTRs, muscle paralysis, coma, respiratory muscle weakness (shallow respirations, apnea)
- Avoid magnesium-containing medications in patients with compromised renal function.
- Monitor cardiac rate and rhythm.
- Monitor neurologic status, including DTRs.
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Phosphate (PO4-)
2.5-4.5 mg/dL |
Hypophosphatemia
- Signs and symptoms (rare unless PO4- less than 1mg/dL)
- Muscle weakness, rhabdomyolysis
- Treatment indicated when PO4- less than 2mg/dL.
- Oral replacement preferred.
- IV indicated if PO4- less than 1mg/dL; administer slowly.
- When administering IV phosphate products, measure serum phosphate levels every 6-8 hours.
- Monitor for hypocalcemia, renal failure, arrhythmias, and diarrhea (with oral replacement).
- Acute or chronic hypophosphatemia can cause rhabdomyolysis.
Hyperphosphatemia
- Signs and symptoms
- Typically asymptomatic
- Clinical features are due to accompanying hypocalcemia (see above)
- Severe hyperphosphatemia can be life threatening.
- Risk factors include advanced renal insufficiency, rhabdomyolysis, tumor-lysis syndrome, and over ingestion of phosphate containing laxatives.
- Soft tissue calcification can be a long-term complication of chronically elevated serum phosphate levels.
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Potassium (K+)
3.5-5 mEq/L |
Hypokalemia
- Signs and symptoms
- Muscle cramps/weakness, rhabdomyolysis, respiratory muscle weakness, decreased bowel motility, cardiac arrhythmias, hypotension, mental status changes, speech changes
- Characteristic ECG findings include ST segment depression, flattened T wave and U wave.
- Monitor cardiac rate and rhythm.
- Common causes include GI losses (diarrhea/vomiting) and diuretic therapy.
- Educate patient on using laxatives and diuretics only as prescribed.
- Monitor potassium levels in patients on digoxin; hypokalemia will potentiate its effects.
- Prolonged hypokalemia can lead to structural and functional changes in the kidneys.
Hyperkalemia
- Signs and symptoms
- Irritability/anxiety, paresthesia, ascending muscle weakness, cardiac arrhythmias, cardiac conduction abnormalities, lethargy, GI symptoms (nausea and intestinal colic)
- Characteristic ECG findings include tall, peaked T waves with shortened QT interval, prolonged PR interval, wide QRS complex and in severe cases, ventricular standstill.
- Monitor cardiac rate and rhythm.
- Avoid potassium-sparing diuretics, potassium supplements, or salt substitutes in patients with renal insufficiency.
- Use ACE inhibitors cautiously, as they cause K+ retention.
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Sodium (Na+)
135-145 mEq/L |
Hyponatremia
- Signs and symptoms
- Neurologic: lethargy, weakness, irritability, confusion, tremors, myoclonus, seizures
- Other: hypotension, GI symptoms (anorexia, nausea, vomiting, abdominal cramping)
- Cerebral edema can occur in rapid reduction of serum sodium concentration
- Correction should be slow (4 to 6 mEq/L in first 24 hours) to avoid osmotic demyelination syndrome; monitor serum Na+ levels and neurologic status frequently.
- Avoid large water supplements to patients receiving isotonic tube feedings.
- Implement seizure precautions in severe cases.
- Monitor fluid losses and gains.
Hypernatremia
- Signs and symptoms
- Excessive thirst, dehydration, dry mucous membranes, oliguria, mental status changes including lethargy, disorientation, restlessness, elevated body temperature.
- Can cause rapid decrease in brain volume potentially leading to rupture of the cerebral veins, subarachnoid hemorrhages and possibly irreversible neurologic damage.
- Monitor fluid losses and gains; urine and plasma osmolality may assist in establishing etiology.
- Give sufficient free water with tube feedings or salt-free IV fluids to keep serum Na+ and BUN within normal limits.
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