At a Glance

Why It's Ordered
To answer ED, ICU and transport questions about electrolyte disturbance, acute kidney injury, glucose derangement, acid-base status and liver injury in patients with altered mental status, weakness, arrhythmia, vomiting, diuretic use or medication toxicity.
Check First
K⁺, HCO₃⁻ with the anion gap, glucose and creatinine: the four values that change management in minutes.
Critical Values
K⁺ <2.5 or ≥6.5 mEq/L · Na⁺ <120 or >160 mEq/L · Glucose <40 or >450 mg/dL · Total Ca <6.0 or >13 mg/dL
Don't Miss
A hemolyzed or fist-clenched sample gives pseudohyperkalemia. Repeat on a clean draw, but treat now if the ECG shows peaked T waves, PR prolongation or QRS widening.
Field & Transport
i-STAT CHEM8+ gives electrolytes, ionized calcium, glucose, BUN and creatinine in minutes, but no liver tests; eGFR depends on analyzer setup. Glucometers read falsely in shock. Send the lab CMP and repeat K⁺ and glucose after any treatment en route.

Panel Overview

The Comprehensive Metabolic Panel (CMP) measures 14 analytes: glucose, calcium, sodium, potassium, chloride, total CO₂, BUN, creatinine, albumin, total protein, alkaline phosphatase (ALP), AST, ALT and total bilirubin. Anion gap, eGFR and BUN:Cr are calculated from these results and are not counted as components. The CMP is one of the most commonly ordered panels in acute care, drawn at ED triage, on ICU morning labs and before interfacility transfer.

The Basic Metabolic Panel (BMP) is the 8-analyte subset of the CMP (glucose, BUN, creatinine, sodium, potassium, chloride, CO₂, calcium). The Renal Panel adds phosphorus and albumin to the BMP. The Liver Panel is the CMP's liver subset (AST, ALT, ALP, bilirubin, albumin, total protein) plus GGT and direct bilirubin.

When to Order:
  • Sepsis or shock: baseline kidney function, electrolytes and acid-base status
  • Altered mental status or seizure: sodium, glucose and calcium as first-line causes
  • Weakness, palpitations or arrhythmia: potassium, calcium and kidney function
  • Diabetic ketoacidosis or hyperosmolar state: glucose, CO₂, anion gap and creatinine
  • Overdose or medication toxicity: electrolytes, kidney function and liver tests, plus the toxicology panel as indicated
  • Pre-procedure or pre-transfer: baseline kidney function, potassium and glucose

Electrolytes

Sodium (Na⁺)

Normal: 135–145 mEq/L

Main extracellular cation that sets serum osmolality. Low values come from water excess, SIADH or diuretics; high values from water loss or hypertonic intake.

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Potassium (K⁺)

Normal: 3.5–5.0 mEq/L

Sets resting membrane potential. Hemolysis or delayed processing can falsely raise it; ECG changes and rhythm matter more than the number alone.

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Chloride (Cl⁻)

Normal: 96–106 mEq/L

Main extracellular anion. Interpret with sodium and CO₂: a high chloride with low CO₂ suggests a non-gap acidosis.

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Total CO₂ (HCO₃⁻)

Normal: 22–29 mEq/L

Serum bicarbonate plus dissolved CO₂. Low values indicate metabolic acidosis or compensated respiratory alkalosis; high values suggest contraction or vomiting.

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Kidney Function

BUN

Normal: 8–23 mg/dL

Urea from protein catabolism. Rises with volume depletion, GI bleeding, high-protein intake and steroids as well as kidney injury; interpret with creatinine.

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Creatinine

Normal: M 0.7–1.3 | F 0.6–1.1 mg/dL

Muscle-derived marker of GFR. Rises late after kidney injury, and a normal value can mask low GFR in older adults or low muscle mass.

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Glucose & Calcium

Glucose

Normal: 70–99 mg/dL (fasting)

Main energy substrate and the first value to check in any altered patient. Low values need treatment before other causes are considered; high values need ketones and osmolality.

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Calcium (Total)

Normal: 8.5–10.5 mg/dL

Total calcium includes protein-bound fractions. Correct for albumin, or measure ionized calcium when albumin is abnormal or during transfusion or critical illness.

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Liver & Proteins

Albumin

Normal: 3.5–5.0 g/dL

Main plasma protein that holds oncotic pressure. Low values reflect liver synthesis, malnutrition or protein loss; albumin is a slow marker, not a measure of acute liver failure.

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Total Protein

Normal: 6.0–8.3 g/dL

Albumin plus globulins. Low values follow malnutrition, liver disease or nephrotic losses; a high value with low albumin suggests a globulin rise.

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ALP

Normal: 30–120 U/L

Alkaline phosphatase from liver, bone and placenta. Rises in cholestasis and bone disease; a raised level in pregnancy can be normal.

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ALT

Normal: 10–40 U/L

Liver-specific aminotransferase. Rises with hepatocellular injury, hepatitis and drug or toxin injury; very high values suggest acute injury.

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AST

Normal: 10–30 U/L

Aminotransferase found in liver, heart and skeletal muscle. Raised in rhabdomyolysis and myocardial injury as well as liver injury, so interpret with ALT.

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Total Bilirubin

Normal: total 0.3–1.2 mg/dL

Hemoglobin breakdown product. Fractionate (direct vs indirect) to separate hemolysis, hepatocellular injury and biliary obstruction.

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Calculated Values

Anion Gap

Normal: 8–12 mEq/L (without K⁺; analyzer-dependent)

Na⁺ − (Cl⁻ + total CO₂). Raised in high-anion-gap acidosis (lactate, ketones, uremia, toxic alcohols, salicylate); normal in non-gap acidosis.

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eGFR

Normal: ≥90 mL/min/1.73 m²

Estimated GFR from creatinine, age and sex using the race-free CKD-EPI 2021 equation. Less accurate in acute kidney injury, where the value is not at steady state.

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BUN:Cr Ratio

Normal: 10:1 to 20:1

Helps separate prerenal azotemia (ratio above 20:1) from intrinsic kidney injury. Unreliable with GI bleeding, steroids or high-protein intake.

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Chemistry Add-Ons (Not CMP Analytes)

Magnesium (Mg²⁺)

Normal: 1.6–2.6 mg/dL (1.3–2.1 mEq/L; 0.65–1.05 mmol/L)

Not a CMP analyte, but often added to it. Low Mg²⁺ brings torsades and potassium that will not correct, and high levels can stop breathing.

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Serum Osmolality

Normal: 275–295 mOsm/kg

Not a CMP analyte, but ordered with it. Measured osmolality, compared with the value calculated from the same draw's sodium, glucose and BUN. A gap above 10 mOsm/kg with an unexplained anion-gap acidosis: consider toxic alcohols.

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Beta-Hydroxybutyrate (BHB)

Normal: lab-specific (mmol/L)

Not a CMP analyte. The main DKA ketone, which a urine dipstick does not measure. At 3.0 mmol/L or higher with glucose ≥11.1 mmol/L or known diabetes, check venous pH and K⁺.

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Lipase

Normal: at or below the lab ULN (U/L)

Not a CMP analyte. A pancreatic enzyme, not a liver test. Above 3 times the ULN with typical pain or imaging supports acute pancreatitis, and a normal value does not rule it out.

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Creatine Kinase (Total CK)

Expected: lab-specific (sex- and assay-dependent)

Not a CMP analyte. Rises with skeletal muscle injury, including rhabdomyolysis; not a cardiac-specific marker. Check potassium, creatinine and urine myoglobin when it is rising.

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Reference Ranges & Critical Values

CMP components: adult reference intervals and typical critical values
TestAdult Normal (conventional)SI UnitsCritical LowCritical HighNotes
Sodium
135–145 mEq/L
135–145 mmol/L
<120
>160
Serum osmolality-linked
Potassium
3.5–5.0 mEq/L
3.5–5.0 mmol/L
<2.5
≥6.5
Hemolysis-prone
Chloride
96–106 mEq/L
96–106 mmol/L
—
—
Interpret with Na⁺ and CO₂
Total CO₂
22–29 mEq/L
22–29 mmol/L
<10
>40
Arterial HCO₃⁻ is 22–26
BUN
8–23 mg/dL
2.9–8.2 mmol/L (urea)
—
—
Age- and protein-dependent
Creatinine
M 0.7–1.3 | F 0.6–1.1 mg/dL
M 62–115 | F 53–97 µmol/L
—
—
Sex-specific; lab-dependent
Glucose
70–99 mg/dL (fasting)
3.9–5.5 mmol/L
<40
>450
Fasting interval
Total Calcium
8.5–10.5 mg/dL
2.12–2.62 mmol/L
<6.0
>13.0
Albumin-dependent
Albumin
3.5–5.0 g/dL
35–50 g/L
—
—
Slow marker
Total Protein
6.0–8.3 g/dL
60–83 g/L
—
—
Albumin + globulin
ALP
30–120 U/L
30–120 U/L
—
—
Pregnancy and bone raise it
ALT
10–40 U/L
10–40 U/L
—
—
ACG healthy ULN 33 M | 25 F
AST
10–30 U/L
10–30 U/L
—
—
Also muscle and heart
Total Bilirubin
0.3–1.2 mg/dL
5–21 µmol/L
—
—
Fractionate if raised
Lab Variation: Intervals and critical lists shift with the lab, the analyzer and the assay. Work from your lab's reported interval and its critical-call policy.

Systematic Interpretation

  1. Sodium and osmolality: Na⁺ tells you whether it is hyponatremia or hypernatremia. Calculated serum osmolality = 2 × Na⁺ + glucose/18 + BUN/2.8 (normal 275–295 mOsm/kg). Correct the sodium for glucose. Add about 1.6 mEq/L for every 100 mg/dL above 100 (up to 2.4 at high glucose).
  2. Potassium with the ECG: K⁺ 6.5 mEq/L or higher is an emergency, and so is any hyperkalemic ECG change, however the number was measured. Before you treat a mild rise, check for hemolysis.
  3. Bicarbonate and anion gap: Anion gap = Na⁺ − (Cl⁻ + total CO₂). Normal is 8–12 mEq/L (analyzer-dependent). A high gap with low CO₂ means a high-anion-gap metabolic acidosis. A normal gap with low CO₂ suggests a non-gap cause.
  4. BUN, creatinine and eGFR: Read creatinine against the baseline. A rise of 0.3 mg/dL within 48 hours, or 1.5 times baseline within 7 days, defines KDIGO AKI. Use BUN:Cr to tell prerenal causes from intrinsic ones.
  5. Glucose: Hypoglycemia gets treated before any other step. In hyperglycemia, check the anion gap, the ketones and the osmolality for a hyperosmolar state.
  6. Calcium corrected for albumin: Corrected Ca = Ca + 0.8 × (4.0 − albumin). Confirm with ionized calcium whenever the albumin is abnormal, the patient is critically ill, or blood has been transfused.
  7. Liver subset: Set ALT and AST against ALP and bilirubin. The R-factor ([ALT/ULN] ÷ [ALP/ULN]) reads above 5 in hepatocellular injury, below 2 in cholestasis, and 2–5 in mixed injury.
Anion gap
Na⁺ − (Cl⁻ + total CO₂); normal 8–12 mEq/L
Corrected calcium
Ca + 0.8 × (4.0 − albumin)
Corrected sodium (glucose)
Na⁺ + 1.6 × [(glucose − 100) ÷ 100]
Worked Example: Run one case through the steps. Start with Na⁺ 130, Cl⁻ 96, total CO₂ 16, glucose 320 mg/dL, BUN 40, creatinine 2.4 mg/dL, Ca 8 mg/dL and albumin 2.5 g/dL. The gap comes out to 130 − (96 + 16) = 18, which is high. Corrected Na⁺ = 130 + 1.6 × 2.2 = 133.5 mEq/L, so the translocational hyponatremia from hyperglycemia is small here. Corrected Ca = 8.0 + 0.8 × 1.5 = 9.2 mg/dL, which is normal. BUN:Cr = 40 ÷ 2.4 = 16.7, which is intermediate.

Patterns & Differential

Each pattern below is a combination of CMP results. Check it against the clinical picture, then run the next test listed.

PatternKey FindingsCommon CausesNext Step
Prerenal AKI
Creatinine up, BUN:Cr above 20:1, low urine sodium
Volume loss, low perfusion, NSAIDs, ACE inhibitor or ARB
Volume status, urine studies, fluid challenge
Intrinsic AKI
Creatinine up, BUN:Cr near 10–15:1, muddy casts
Ischemic or toxic tubular injury, sepsis, contrast
Urinalysis, urine sodium, nephrology if persistent
High-anion-gap acidosis
Anion gap above 12 with low CO₂
Lactate, ketones (DKA, starvation), uremia, toxic alcohols, salicylate
Lactate, beta-hydroxybutyrate, osmolar gap, toxicology
Normal-anion-gap acidosis
Normal gap, high chloride, low CO₂
Diarrhea, renal tubular acidosis, saline-heavy fluids
Urine anion gap, stool or urine electrolytes
Hypovolemic hyponatremia
Low Na⁺, low serum osmolality, low urine sodium
Diuretics, GI losses, third-spacing
Volume exam, urine sodium and osmolality
SIADH
Low Na⁺ and osmolality, urine osmolality inappropriately high, normal volume
Medications, CNS disease, pulmonary disease, malignancy
Exclude hypothyroidism and adrenal insufficiency first
Hypercalcemia
Corrected Ca above 10.5 mg/dL, often with low phosphorus
Hyperparathyroidism, malignancy, thiazides, vitamin D excess
Ionized calcium, PTH, medication review
Cholestatic pattern
ALP and bilirubin up, ALT near normal, R-factor below 2
Biliary obstruction, drug-induced cholestasis, infiltrative liver disease
Liver ultrasound, GGT, refer to the liver panel

Serial Testing & Kinetics

AnalyteChanges AfterPeak or NadirRepeat IntervalMonitoring Target
Potassium
Insulin, beta-agonist or binder treatment
Early effect, then rebound
1, 2, 4, 6 and 24 hr after treatment (UKKA 2026 guideline)
K⁺ below 6.0 mEq/L and no ECG change
Glucose
Insulin infusion or insulin-glucose bolus
Falls within 1 hr; late hypoglycemia possible
Before the dose, then at 30, 60, 90, 120, 180, 240, 300 and 360 min (at least 6 hr; UKKA 2026 guideline). Extend beyond 6 hr after repeat doses or in high-risk patients (see Pitfall)
Glucose above 70 mg/dL
Sodium
Hypertonic saline bolus
Rise within 1 hr of a bolus
After each bolus; every 2–4 hr while infusing
Rise limited to 8–12 mEq/L per 24 hr by ODS risk (see Critical Findings)
Creatinine
Kidney injury
Rises over 24–48 hr
Every 24 hr until stable
Stable or falling creatinine
Ionized calcium
IV calcium or massive transfusion
Effect within minutes, lasts 30–60 min
After each dose and with each blood gas during transfusion
Ionized calcium within the lab range

Critical Findings & Emergency Actions

Hyperkalemia with ECG changes or K⁺ 6.5 mEq/L or higher

Recognize: peaked T waves, PR prolongation, lost P waves, QRS widening, bradycardia or sine wave. When the ECG changes are present, treat now. Don't wait for a repeat level.

  1. Protect the heart (Paramedic/RN/CCT): with a pulse and hyperkalemic ECG changes or arrhythmia, calcium gluconate 10%, 30 mL (3 g) IV over 10 min through a large vein (a peripheral vein will do). Use calcium chloride 10%, 10 mL (1 g) IV over 5 min for peri-arrest only, or through a central or large proximal vein, since a leak out of the vein does more harm than with gluconate. For cardiac arrest or peri-arrest, give calcium chloride 10%, 10 mL (1 g) IV/IO push (UKKA 2026 guideline). Look at the ECG again about 3 min after the dose. If the ECG changes persist, or K⁺ is still high after about 60 min, repeat the same dose. Keep calcium out of the same line as bicarbonate or phosphate. In suspected digoxin toxicity, IV calcium is for life-threatening hyperkalemia only, per medical direction. Differs from FDA label: US labels cover only hypocalcemia and cap the rate (calcium gluconate 200 mg/min for adults, so 3 g takes at least 15 min, and calcium chloride 1 mL/min through a central or deep vein with no bolus). The rate used on this page (gluconate 30 mL over 10 min, chloride 10 mL over 5 min) comes from UKKA 2026. It is off-label.
  2. Shift K⁺ into cells: High-alert regular insulin 10 units IV, drawn up into the dextrose syringe along with dextrose 25 g (50 mL D50, or 125 mL D20, or 250 mL D10) and pushed over 5–15 min into a large vein. Recommended at K⁺ 6.5 or higher. Suggested at 6.0–6.4. Always give the dextrose. Do not swap in glucose alone. If K⁺ is still not below 6.0 at 2 hr, consider a second dose, and stretch out the glucose checks (UKKA 2026 guideline).
  3. Prevent hypoglycemia: when pre-treatment glucose is under 126 mg/dL (7 mmol/L), run D10 50 mL/hr for 5 hr (UKKA 2026 guideline). Glucose gets checked before the dose and then at 30, 60, 90, 120, 180, 240, 300 and 360 min (at least 6 hr). Keep checking past 6 hr after repeat insulin doses, or in high-risk patients (low pre-dose glucose, kidney impairment, low body weight, older age). Glucose under 70 mg/dL gets the hypoglycemia steps below.
  4. Adjunct: nebulized albuterol 10–20 mg (UKKA 2026: an adjunct only, not monotherapy for severe hyperkalemia). Stay at 10 mg in ischemic heart disease. Off-label dose (label nebulized dose is 2.5 mg for asthma). The 10–20 mg figure comes from UKKA 2026. High-dose albuterol drives the heart rate up and can provoke ischemia or arrhythmia. Go carefully in patients with ischemia or tachyarrhythmia. In cardiac arrest, the 2025 AHA Guidelines for CPR and ECC, Part 10 advise against inhaled beta-2 agonists (class 3: No Benefit, LOE C-EO).
  5. Remove K⁺ and recheck: sodium zirconium cyclosilicate (Lokelma) 10 g PO three times daily for up to 48 hr, added on to calcium and insulin-glucose (US label; UKKA 2026 allows up to 72 hr). Differs from FDA label: the label warns against SZC as emergency treatment for life-threatening hyperkalemia, because it acts slowly. UKKA 2026 backs it as an add-on to calcium and insulin-glucose in severe hyperkalemia. A hemodialysis patient with K⁺ 6.5 or higher needs urgent dialysis (UKKA 2026 guideline). In any life-threatening or treatment-resistant case, ask for an urgent nephrology or critical-care decision on dialysis. Recheck K⁺ at 1, 2, 4, 6 and 24 hr. Rebound is common.

Note: Outside arrest, IV sodium bicarbonate is not routine for acute hyperkalemia (UKKA 2026 guideline). Calcium does not lower K⁺ at all. It protects the heart muscle while the K⁺ is being shifted. In cardiac arrest from suspected hyperkalemia (2025 AHA Guidelines for CPR and ECC, Part 10, Electrolyte Abnormalities: Hyperkalemia): For IV calcium (calcium chloride 10 mL, 1 g IV/IO push), the class is 2b (LOE C-LD), and IV sodium bicarbonate and IV insulin with glucose are also class 2b (LOE C-EO), since their effectiveness is still poorly established. In arrest without a suspected hyperkalemic cause, routine calcium is not recommended (2025 AHA Part 9, COR 3: No Benefit). Bicarbonate runs at 50 mEq IV/IO, repeated every 5–10 min guided by blood gas (US label; UKKA 2026 suggests, 2C). Inhaled beta-2 agonists sit at class 3: No Benefit. For adults in arrest, AHA Table 3 gives regular insulin 10 units IV over 15–30 min with D50 50 g. Differs from UKKA 2026 and ERC: They give 25 g, plus D10 50 mL/hr if glucose is under 126 mg/dL. AHA 2025 Table 3 gives 50 g. In hyperkalemic arrest, AHA rates insulin-glucose COR 2b, with effectiveness not well established. Some US protocols give 5 units or 0.1 units/kg instead. A pooled analysis of 10 retrospective studies found less hypoglycemia with lower doses, and the K⁺ fall did not differ (see References). A later study found that 10 units lowered K⁺ more (0.9 vs 0.63 mmol/L, see References). UKKA 2026 says more study is needed before 5 units can be recommended. The glucose rules above come with the 10 units this site uses.

Severe symptomatic hyponatremia (seizure, coma or respiratory distress)

Recognize: Think hypotonic hyponatremia with neurologic symptoms. Acute or chronic, treat now. If a sample is quick to draw, check the sodium and serum osmolality. Don't hold treatment for the result.

  1. Airway and perfusion (Paramedic/RN/CCT): protect the airway, check the glucose, and give oxygen as needed.
  2. High-alert 3% NaCl: 100–150 mL IV over 10–20 min. The US expert panel gives 100 mL over 10 min, repeated up to 3 times. The European guideline gives 150 mL over 20 min, repeated once or twice. Repeat as the protocol says.
  3. Recheck sodium after each bolus. Aim for a 4–6 mEq/L rise to reverse the symptoms. In high-risk patients, cap the rise at 8 mEq/L per 24 hr (hypokalemia, alcohol use disorder, malnutrition, advanced liver disease). The US standard-risk limit is 10–12 mEq/L per 24 hr. The European limit is 10 mEq/L in the first 24 hr, then 8 mEq/L per later 24 hr. These limits are there to prevent osmotic demyelination.
  4. Do not free-flow hypertonic saline: Run it as a timed bolus or per pump protocol.
  5. If overcorrected or the limit is exceeded: shut off the hypertonic saline. Call for a consult on D5W and/or desmopressin to lower sodium again.

Hypoglycemia (glucose below 70 mg/dL with symptoms)

Recognize: Watch for sweating, confusion, seizure or unresponsiveness. Check glucose first in every altered patient, before you consider any other cause.

  1. Alert and able to swallow: take 15–20 g of fast-acting carbohydrate by mouth (ADA Standards of Care, Section 6), then check glucose again per protocol.
  2. Cannot swallow safely (Paramedic/RN/CCT): dextrose 10 g IV (100 mL of D10), given in 5 g steps, rechecking glucose after each step until alert. The field maximum is 25 g per dosing episode, then per medical direction (E3 dextrose page).
  3. No IV or IO access: use glucagon 1 mg IM or subcutaneous (labeled routes), or intranasal or autoinjector glucagon where stocked, per protocol.
  4. Sulfonylurea or long-acting insulin: expect it to come back, so keep watching for several hours after treatment.

Symptomatic hypocalcemia (tetany, seizure, QT prolongation or hypotension)

Recognize: carpopedal spasm, laryngospasm, seizure, QT prolongation. Check both ionized calcium and magnesium.

  1. Calcium chloride 10%: 200–1,000 mg (2–10 mL) IV, go slowly, no faster than 1 mL/min. Maximum 1,000 mg per dose; repeat as the ionized calcium directs (labeled dose). A central or large vein is preferred.
  2. Treat hypomagnesemia if it is present. Replace calcium without fixing magnesium and the hypocalcemia stays.
  3. Massive transfusion: during massive transfusion, check ionized calcium with each blood gas and treat per the transfusion protocol.

Severe hypercalcemia or severe metabolic acidosis

Recognize: total Ca above 13 mg/dL (critical high) with confusion, vomiting or polyuria; or pH below 7.20 with low CO₂.

  1. Hypercalcemia (RN/CCT): isotonic saline per protocol. Stop thiazides and other calcium-raising drugs. Transfer for definitive treatment.
  2. Acidosis (ICU): start with the cause (insulin and fluids in DKA, perfusion in shock, toxic ingestion). Whether to give sodium bicarbonate depends on the protocol. It is not a routine step for hyperkalemia (UKKA 2026 guideline).

Severe hypokalemia (K⁺ below 2.5) or severe hypernatremia (Na⁺ above 160)

Recognize: hypokalemia with arrhythmia, weakness or paralysis; hypernatremia with confusion, seizure or altered consciousness. Treat per local protocol and medical direction.

  1. Hypokalemia (ICU/CCT): Monitor the ECG continuously. Check and replace magnesium. IV potassium chloride through a pump at a controlled rate per protocol, never as a bolus, and repeat the level and ECG during replacement.
  2. Hypernatremia (ICU): work out the free-water deficit and replace it by whatever route is open, correcting slowly (about 10–12 mEq/L per 24 hr, per protocol) so the brain does not swell. Recheck sodium at the protocol interval.
Pitfall: Insulin alone drops the glucose, and the low shows up late. Give the dextrose, and check glucose at 30, 60, 90, 120, 180, 240, 300 and 360 min after insulin, for at least 6 hr. Keep going past that after repeat doses or in high-risk patients.

Prehospital & Transport Considerations

Point-of-Care Testing

Device / MethodAnalytesSpecimenLimitations
i-STAT CHEM8+
Na⁺, K⁺, Cl⁻, iCa, glucose, BUN, creatinine, TCO₂
Whole blood, heparinized
No liver tests; eGFR reporting depends on analyzer configuration; cartridge temperature and storage limits
i-STAT CG8+ or blood-gas cartridge
Electrolytes, iCa, glucose, lactate, Hct
Whole blood, heparinized
Used for arterial or venous samples; follow the cartridge insert
Glucometer
Glucose only
Capillary blood
Unreliable in shock or hypoperfusion; interference from maltose, icodextrin and high-dose vitamin C

Interfacility Transfer & Handoff

  • Send the results and the times they were drawn, with any pending CMP components and the most recent creatinine trend.
  • Record active treatment: insulin or dextrose infusions, calcium doses, and any hypertonic saline volume and the time of the next sodium check.
  • Repeat K⁺ and glucose on arrival and after any treatment en route, per the protocol timing above.
  • Specimen handling: send lab samples on ice when the analyte is unstable, and follow lab rules for air transport (temperature and pressure effects on tubes).

Scope Notes

  • EMS: Point-of-care glucose is the baseline, and i-STAT electrolytes are there where they are stocked. Calcium and insulin availability varies by EMS system. Where they are not carried, the answer is early transfer per protocol.
  • Transport (CCT): the transport team runs the infusions and the repeat labs. For suspected hyperkalemia, calcium gluconate 10%, 30 mL (3 g) IV over 10 min is the default for a patient with a pulse; calcium chloride 10%, 10 mL (1 g) is used for arrest or peri-arrest, or through central, deep or large proximal access (UKKA 2026 guideline). Calcium-channel-blocker toxicity runs on its own toxicology protocol. This hyperkalemia rule does not apply to it.
  • Scope varies: follow local protocols and medical direction for every drug in this section.

Special Populations

Pediatrics

Several analytes have age-specific reference intervals in children. The age-band tables are not on this page, so use the laboratory's pediatric table. The weight-based doses are listed below (see weight-based dosing and pediatric vital signs).

IndicationPediatric DoseMax / RepeatNotes
Hyperkalemia with ECG changes
Calcium chloride 10%: 20 mg/kg (0.2 mL/kg of 10%) IV/IO slowly; push in arrest
Max 1 g per dose; repeat if ECG toxicity persists
Equivalent calcium gluconate 60 mg/kg (0.6 mL/kg of 10%), max 3 g. Per-kg dose not verified in a primary source
Hyperkalemia (insulin)
Regular insulin 0.1 units/kg IV with dextrose 0.5 g/kg
Max 10 units per dose
Cardiac arrest dosing per 2025 AHA Guidelines for CPR and ECC, Part 10 (Table 3): regular insulin 0.1 units/kg IV over 15–30 min with D10W 5 mL/kg; maximum 10 units for severe hyperkalemia. Outside arrest, per pediatric protocol with glucose checks as adult
Hypoglycemia
Dextrose 0.5–1 g/kg IV/IO (D10 5–10 mL/kg preferred)
Max 25 g per dose; reassess after each dose
D10 preferred at every age
Severe symptomatic hyponatremia
3% NaCl 2 mL/kg IV over 10 min
Max 100 mL per dose; recheck Na⁺
High-alert; never free-flow
Symptomatic hypocalcemia
Calcium chloride 10%: protocol range 10–20 mg/kg IV slowly
Max 1 g per dose
Per-kg range not verified in a primary source; check a pediatric formulary

Pregnancy

Pregnancy changes the picture. Dilution lowers hemoglobin and sodium. A respiratory alkalosis is normal here, with PaCO₂ around 28–32 mmHg and HCO₃⁻ around 18–21 mEq/L. The placenta pushes ALP up. Creatinine above 0.8 mg/dL is abnormal. A pregnant patient with headache, hypertension or right-upper-quadrant pain needs ALT, AST and platelets checked. Think HELLP syndrome or preeclampsia. Treat hyperkalemia and hypoglycemia in pregnancy as you would in non-pregnant adults.

Older Adults

A normal creatinine can hide a markedly reduced GFR when muscle mass is low. Use eGFR, and cystatin C where the lab offers it (2021 race-free CKD-EPI creatinine-cystatin equation). In this group, the usual causes of hyperkalemia, hyponatremia and AKI are volume depletion and polypharmacy (diuretics, ACE inhibitors, ARBs, potassium-sparing drugs).

CKD and Dialysis

Read K⁺ and HCO₃⁻ against the dialysis schedule. The pre-dialysis sample is the reference. RAAS inhibitors, mineralocorticoid antagonists and tissue breakdown all push hyperkalemia risk up. Dialysis patients with severe hyperkalemia need urgent dialysis. IV calcium should still go in for ECG changes while dialysis is being arranged (UKKA 2026 guideline). Low albumin and fluid overload both change the calcium and sodium readings.

Specimen Collection & Interfering Factors

  • Tube: gold or green (lithium heparin or serum separator) for the CMP. Tube color depends on the institution, so follow your lab's label.
  • Fill: fill the tube to the line. An under-filled tube reads falsely low for some analytes.
  • Handling: separate serum or plasma from cells within the lab's time limit. Waiting too long lowers glucose and raises potassium.
  • Order of draw (CLSI GP41): blood cultures, light blue (citrate), red or gold (serum), green (heparin), lavender (EDTA), gray (fluoride).
InterferentEffect on ResultsPrevention
Hemolysis
Falsely high K⁺, AST, LDH, phosphorus
Avoid fist clenching and prolonged tourniquet; repeat on a clean draw
Drawing above an IV line
Dilution: low values for sodium, glucose and protein; high K⁺ if K⁺ is in the fluid
Draw from the opposite arm or stop infusion and flush per protocol
EDTA contamination
Falsely high K⁺, low calcium and ALP
Correct order of draw; do not pour between tubes
Delayed processing
Low glucose, high K⁺ and phosphorus
Process promptly or separate serum from cells
Lipemia or icterus
Analyzer interference, especially for some enzymes and bilirubin
Check the lab's hemolysis, lipemia and icterus indices
Biotin
Interferes with streptavidin-biotin immunoassays (for example, some troponin and TSH assays); routine CMP chemistries are generally unaffected
Ask about supplements; hold biotin 2–3 days before the draw if the lab advises

Clinical Pearls

Check glucose in every altered patient: Treat hypoglycemia first. Don't wait for the rest of the panel.
Anion gap first, then the cause: Look at the gap before you chase the cause. Raised gap with low CO₂? Think lactate, ketones, uremia, toxic alcohols or salicylate.
Calcium must be corrected or measured: Total calcium on this panel misleads when albumin is low. In critical illness, measure the ionized calcium.
Creatinine lags: It rises 24–48 hours after kidney injury. A normal value early on does not rule out AKI.
Field and transport: Point-of-care electrolytes are fast. Liver tests still need a lab CMP.
Nursing: IV calcium goes IV or IO, and nowhere else. Never give it IM or subcutaneously. A leak into the tissue causes tissue necrosis.
Critical care: Repeat K⁺ at 1, 2, 4, 6 and 24 hours after treatment. Insulin and beta-agonist effects wear off.
Pitfall: Hemolysis produces pseudohyperkalemia, a falsely high potassium. Repeat the draw, but treat now if the ECG shows toxic changes.
Pitfall: Push the correction past the limit for this patient's risk and it causes osmotic demyelination. Check sodium after every bolus.

References

  1. Inker LA, Eneanya ND, Coresh J, et al. New creatinine- and cystatin C-based equations to estimate GFR without race. N Engl J Med. 2021;385(19):1737–1749. https://www.nejm.org/doi/full/10.1056/NEJMoa2102953
  2. KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease. Kidney Int. 2024;105(4S):S117–S314. https://kdigo.org/guidelines/ckd-evaluation-and-management/
  3. KDIGO Clinical Practice Guideline for Acute Kidney Injury. Kidney Int Suppl. 2012;2(1):1–138. https://kdigo.org/guidelines/acute-kidney-injury/
  4. UK Kidney Association. Clinical practice guideline: management of hyperkalaemia in adults (updated July 2026). https://www.ukkidney.org/sites/default/files/documents/FINAL%20VERSION%20-%20UKKA%20CLINICAL%20PRACTICE%20GUIDELINE%20-%20MANAGEMENT%20OF%20HYPERKALAEMIA%20IN%20ADULTS%20-%20UPDATED%20JULY%202026_0.pdf
  5. Spasovski G, Vanholder R, Allolio B, et al. Clinical practice guideline on diagnosis and treatment of hyponatraemia. Nephrol Dial Transplant. 2014;29(suppl 2):i1–i39. https://doi.org/10.1093/ndt/gfu040
  6. Verbalis JG, Goldsmith SR, Greenberg A, et al. Diagnosis, evaluation, and treatment of hyponatremia: expert panel recommendations. Am J Med. 2013;126(10 suppl 1):S1–S42. https://doi.org/10.1016/j.amjmed.2013.07.006
  7. American Diabetes Association Professional Practice Committee. 6. Glycemic goals, hypoglycemia, and hyperglycemic crises: Standards of Care in Diabetes—2026. Diabetes Care. 2026;49(suppl 1):S132–S149. https://doi.org/10.2337/dc26-S006
  8. 2025 AHA Guidelines for CPR and ECC, Part 10: Adult and Pediatric Special Circumstances of Resuscitation (Electrolyte Abnormalities: Hyperkalemia, Table 3). https://cpr.heart.org/en/resuscitation-science/cpr-and-ecc-guidelines/adult-and-pediatric-special-circumstances-of-resuscitation
  9. Moussavi K, et al. Reduced alternative insulin dosing in hyperkalemia: a meta-analysis of effects on hypoglycemia and potassium reduction. Pharmacotherapy. 2021. doi:10.1002/phar.2596
  10. Finder, et al. 5 versus 10 units of intravenous insulin for hyperkalemia in patients with moderate renal dysfunction. J Emerg Med. 2022. https://doi.org/10.1016/j.jemermed.2021.10.027

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