What electrolytes does this tool cover?

This reference covers the four most commonly replaced electrolytes in adult inpatient care: potassium (K+), magnesium (Mg2+), phosphate (PO4), and sodium (Na+).

Are these dose recommendations specific to my patient?

No. These are typical adult reference ranges and protocol examples based on standard US clinical practice. Actual dosing must be determined by a physician based on renal function, comorbidities, medications, and clinical context.

Why is the sodium correction rate important?

Correcting hyponatremia too quickly (more than 8–10 mEq/L per 24 hours) risks osmotic demyelination syndrome (ODS), a serious neurological complication. The rate limit shown is a guideline — always individualize with nephrology input for severe cases.

Can I use this for pediatric patients?

No. These values apply to adult patients only. Pediatric electrolyte ranges and replacement doses differ significantly by age and weight.

What sources are these guidelines based on?

Data reflects commonly cited adult protocols from US clinical practice, including standard pharmacology references and institutional guidelines. Always verify against your institution's protocols and current evidence.

Electrolyte Replacement Reference

Name: Electrolyte Replacement Reference
Availability: InStock
Author: Nham Vu

Clinical reference for electrolyte replacement guidelines: normal ranges, deficiency thresholds, and IV/oral protocols for K+, Mg2+, PO4, and Na+.

Clinical Reference Only

Electrolyte replacement must be guided by a physician. Doses depend on renal function, patient weight, comorbidities, and clinical context. This tool shows typical adult reference ranges and protocols — not individualized recommendations.

Potassium (K+)

Normal serum range: 3.5 – 5.0 mEq/L

Deficiency Thresholds

Severity	Serum K+	Typical Symptoms
Mild	3.0 – 3.5 mEq/L	Often asymptomatic; mild weakness, fatigue
Moderate	2.5 – 3.0 mEq/L	Muscle cramps, weakness, EKG changes (flattened T, U waves)
Severe	< 2.5 mEq/L	Paralysis, rhabdomyolysis, life-threatening arrhythmias

Replacement Protocols

Route	Agent	Typical Dose / Rate	Notes
Oral	KCl (tab/liquid)	20 – 80 mEq/day in divided doses	Preferred for mild/moderate; give with food to reduce GI upset
IV — peripheral	KCl in NS or D5W	10 mEq/hr; max 40 mEq/L concentration	Higher concentrations cause phlebitis and pain; use central line for concentrated infusions
IV — central	KCl concentrated	10 – 20 mEq/hr; up to 200 mEq/L concentration	Continuous cardiac monitoring required at rates >10 mEq/hr; recheck K+ after each 40 mEq infused

Monitoring: Recheck serum K+ 2–4 hours after IV replacement. Correct concurrent hypomagnesemia — refractory hypokalemia often resolves only after Mg2+ is repleted.

Magnesium (Mg2+)

Normal serum range: 1.7 – 2.2 mg/dL (0.7 – 0.9 mmol/L)

Deficiency Thresholds

Severity	Serum Mg2+	Typical Symptoms
Mild	1.2 – 1.7 mg/dL	Often asymptomatic; anorexia, nausea, fatigue
Moderate	0.8 – 1.2 mg/dL	Muscle tremors, weakness, refractory hypokalemia/hypocalcemia
Severe	< 0.8 mg/dL	Tetany, seizures, cardiac arrhythmias, Torsades de Pointes

Replacement Protocols

Route	Agent	Typical Dose / Rate	Notes
Oral	Mg oxide / Mg gluconate	400 – 800 mg/day elemental Mg in divided doses	Diarrhea is dose-limiting; use lower doses for outpatient repletion
IV — moderate	MgSO4 in NS or D5W	1 – 2 g IV over 1 – 2 hours	Monitor BP and deep tendon reflexes; loss of DTRs signals toxicity
IV — severe/symptomatic	MgSO4	2 – 4 g IV over 5 – 15 min (emergent); then 1 g/hr infusion	Only in setting with cardiac monitoring and calcium gluconate immediately available for reversal

Monitoring: Recheck serum Mg2+ 4–6 hours after IV. Reduce dose in renal impairment (GFR < 30 mL/min). Hypomagnesemia commonly co-occurs with hypokalemia and hypocalcemia; check and correct all three.

Phosphate (PO4)

Normal serum range: 2.5 – 4.5 mg/dL (0.8 – 1.45 mmol/L)

Deficiency Thresholds

Severity	Serum PO4	Typical Symptoms
Mild	2.0 – 2.5 mg/dL	Often asymptomatic; mild muscle weakness
Moderate	1.0 – 2.0 mg/dL	Weakness, bone pain, impaired respiratory muscle function, hemolysis
Severe	< 1.0 mg/dL	Respiratory failure, encephalopathy, rhabdomyolysis, cardiac dysfunction

Replacement Protocols

Route	Agent	Typical Dose / Rate	Notes
Oral — mild	Neutra-Phos / Fleet Phos-Soda	250 – 500 mg elemental PO4 TID–QID	Preferred when GI tract functional; diarrhea is common dose-limiting effect
IV — moderate	Na or K phosphate	15 – 30 mmol IV over 2 – 6 hours	Choose K-phosphate cautiously if concurrent hyperkalemia; monitor electrolytes during infusion
IV — severe	Na or K phosphate	30 – 45 mmol IV over 4 – 6 hours	Risk of hypocalcemia, hypotension, metastatic calcification; monitor Ca2+, Mg2+, K+

Monitoring: Recheck serum PO4 4–6 hours after IV dose. Avoid IV phosphate if serum Ca2+ is elevated — risk of calcium phosphate precipitation. Reduce dose in renal impairment.

Sodium (Na+)

Normal serum range: 136 – 145 mEq/L

Correction rate limit: Do not raise serum Na+ by more than 8 – 10 mEq/L per 24 hours (or ~0.5 mEq/L/hr) to avoid osmotic demyelination syndrome (ODS). In patients at high ODS risk (alcoholism, malnutrition, liver disease), limit to 6–8 mEq/L per 24 hours.

Deficiency Thresholds (Hyponatremia)

Severity	Serum Na+	Typical Symptoms
Mild	130 – 135 mEq/L	Often asymptomatic; nausea, malaise, headache
Moderate	125 – 130 mEq/L	Vomiting, confusion, gait instability, falls
Severe	< 125 mEq/L	Seizures, coma, respiratory arrest, herniation

Replacement Protocols

Route / Scenario	Agent	Typical Approach	Notes
Mild / asymptomatic	Fluid restriction / treat underlying cause	Restrict free water to 800 – 1000 mL/day; address SIADH cause	SIADH: demeclocycline or tolvaptan for refractory cases; nephrology consult
Hypovolemic	0.9% NaCl (normal saline)	250 – 500 mL boluses; adjust rate to correct Na+ at ≤ 0.5 mEq/L/hr	Serial Na+ checks every 2–4 hours; adjust rate accordingly
Severe / symptomatic	3% NaCl (hypertonic saline)	100 mL bolus IV over 10 min; repeat up to 3 times PRN for active seizures	ICU or step-down setting; frequent Na+ checks (q1–2hr); goal is symptom control, not full normalization

Monitoring: Check serum Na+ every 2–4 hours during active correction. If Na+ rises faster than the daily limit, administer free water (D5W or oral water) to slow the rate. Nephrology or endocrinology involvement is strongly recommended for severe or refractory cases.

Summary

Clinical reference for electrolyte replacement guidelines: normal ranges, deficiency thresholds, and IV/oral protocols for K+, Mg2+, PO4, and Na+.

How it works

Select an electrolyte tab (K+, Mg2+, PO4, or Na+).
Review the normal serum range and deficiency severity thresholds.
Consult the replacement protocol table for typical IV and oral dosing ranges.
Use the monitoring notes to understand follow-up lab timing.
Always confirm orders with a physician — this tool is reference only.

Use cases

Quick bedside reference for electrolyte deficiency thresholds in adult patients.
Review IV potassium replacement rates and maximum concentrations before ordering.
Look up phosphate replacement options (oral vs IV) based on deficiency severity.
Reference hyponatremia correction rate limits to avoid osmotic demyelination syndrome.
Medical student or resident study aid for electrolyte physiology and management.

Frequently Asked Questions

Last updated: 2026-07-23 · Reviewed by Nham Vu