A free NCLEX-RN® lab values cheat sheet for 2026, covering potassium, sodium, calcium, magnesium, chloride, creatinine, BUN and eGFR.
Every row gives you three things: the reference range, what the reading means, and the first nursing action. The whole sheet is on this page. Print it or save it as a PDF from your browser.
Mariano Alfred Acevedo, PhD, RNFounder and Curriculum Director · Jade NursingPrep™Updated September 6, 2026
On the NCLEX-RN®, an item that gives you a numeric lab value also gives you its normal reference range. NCSBN® states this on the exam's own site.
“Do items provide the candidate with normal reference ranges?”
“Beginning with the launch of the Next Generation NCLEX, items that contain a numeric laboratory value will include the corresponding normal reference range.”
Cardiac monitor and ECG. Anticipate IV calcium gluconate to stabilize the myocardium — it does not lower the potassium, it buys time.
5.1–6.0 mEq/L
Hyperkalemia
Look for tall, peaked T waves — the earliest change. Hold potassium supplements and salt substitutes; review contributing medications.
3.5–5.0 mEq/L
Normal
—
3.0–3.4 mEq/L
Hypokalemia
Flattened T waves, ST depression, prominent U waves. Check the magnesium and the digoxin toxicity risk.
Below 3.0 mEq/L
Critical low
Cardiac monitor, ECG, notify the provider. Replace only by pump, never by IV push, with urine output confirmed.
Potassium ranges vary slightly by laboratory and testing program; some sources list 3.5–5.1 mEq/L. Full guide: Potassium for the NCLEX-RN®.
Sodium
Normal serum sodium about 135–145 mEq/L
Reading
What it means
First nursing action
Above 145 mEq/L
Hypernatremia
Read the water first — dry mouth, thirst and weight loss point to water deficit; edema and weight gain point to sodium excess. Correct slowly per order; too fast risks cerebral edema.
135–145 mEq/L
Normal
—
Below 135 mEq/L
Hyponatremia
Branch on volume status: dry, euvolemic (think SIADH), or overloaded. Fluid restriction for SIADH and overload.
Below about 125 mEq/L, or any level with a new seizure or falling level of consciousness
Severe
Protect the brain — seizure precautions, frequent neuro checks, airway, stay with the client. Anticipate 3% hypertonic saline only as ordered, by pump, with serial sodium checks.
Sodium is corrected slowly — providers commonly hold the rise to roughly 8–10 mEq/L over 24 hours, and even less in higher-risk patients. Full guide: Sodium for the NCLEX-RN®.
Calcium
Total calcium ~8.5–10.5 mg/dL · ionized calcium ~4.5–5.5 mg/dL
Reading
What it means
First nursing action
Above ~14 mg/dL
Severe high calcium
Treated as an emergency, especially with confusion, dehydration, or rhythm changes. IV normal saline first — rehydration is the first step; a loop diuretic is used only after fluids are running.
Above the upper limit (total)
Hypercalcemia
Assess for the Stones, Bones, Groans, and Psychic Moans cluster and notify with the full picture. QT shortened is the cardiac change — keep continuous monitoring.
Total ~8.5–10.5 mg/dL · ionized ~4.5–5.5 mg/dL
Normal
Check the albumin so a low albumin does not read as a “false low.” Ionized calcium is the more reliable read when albumin is abnormal.
Below ~8.8 mg/dL (total)
Hypocalcemia
Assess for symptoms (CATS go numb) and notify with the full picture. QT prolonged is the cardiac change. A low magnesium keeps calcium low; calcium may not recover until magnesium is corrected.
IV calcium safety
Administration
Given slowly, never into muscle or under the skin; calcium chloride is preferred through a central line; watch the IV site for leaking (extravasation).
A thiazide raises calcium (flag it for the provider); a loop diuretic helps lower it after rehydration.
Magnesium
Normal serum magnesium about 1.5–2.5 mEq/L
Direction
The bedside picture
First nursing action
High — above about 2.5 mEq/L
Reflexes diminish then disappear, weakness, flushing and warmth, falling blood pressure, drowsiness, slowed breathing
Stop the magnesium source. Support breathing. Notify the provider. Prepare and administer the ordered IV calcium — commonly calcium gluconate. Dialysis when the level is very high or the kidneys cannot clear it.
About 1.5–2.5 mEq/L
Normal
—
Low — below about 1.5 mEq/L
Hyperactive reflexes, tremor, twitching, prolonged QT that can slide into Torsades de Pointes
Monitor the rhythm. Replace magnesium slowly by pump, only as ordered, watching for overshoot. Check the potassium and calcium riding along with it.
Some laboratories report the normal range as about 1.6–2.2 mg/dL — ranges vary by laboratory; use your facility's values. Full guide: Magnesium for the NCLEX-RN®.
Chloride
Published example normal serum chloride ~97–107 mEq/L
Number / threshold
Clinical meaning
~97–107 mEq/L
A published example normal serum chloride range. Below it is hypochloremia; above it is hyperchloremia. Always read the facility's printed range, which varies by lab and assay.
Critical: below ~80 or above ~115 mEq/L
Example critical-reporting values — results this far outside the range are reported promptly per facility policy. A critical-value reporting point, not a severity scale.
The inverse rule
Chloride and bicarbonate move in opposite directions. High chloride → expect low bicarbonate → acidosis. Low chloride → expect high bicarbonate → alkalosis. Read them together and report the pattern.
0.9% normal saline = 154 mEq/L chloride
0.9% saline carries 154 mEq/L of sodium and 154 mEq/L of chloride — well above the body's normal chloride. Large-volume infusion can drive a hyperchloremic acidosis; monitor the trend and report it.
Anion gap ~8–16 (conceptual)
Sodium minus (chloride plus bicarbonate); the traditional reference range is about 8–16 and varies by assay. Reasoning context, not a bedside calculation — the provider interprets it.
Creatinine
Published adult example 0.74–1.35 mg/dL (men) · 0.59–1.04 mg/dL (women)
What you are looking at
What it means
First nursing action
Rise of 0.3 mg/dL within 48 hours
AKI Stage 1
The criterion is met even when the current value still reads inside the printed range. Document both values with their draw times side by side. Begin or confirm hourly urine output, and flag nephrotoxic medications for provider review.
Rise to 1.5–1.9× a known or presumed baseline within 7 days
AKI Stage 1
Pull the outpatient or admission creatinine before interpreting today's value. Report the change against baseline, not the absolute number, and confirm the next serial draw.
Urine output under 0.5 mL/kg/hr for 6–12 hours
AKI Stage 1
This meets a Stage 1 trigger on its own, and output moves faster than creatinine does. Measure and document hourly, with the time on every check. Flag any hour under 30 mL.
Creatinine at or below 1.0 mg/dL with an eGFR under 60
The bedside trap
Low muscle mass, frailty, amputation or severe liver disease lowers production, so a “normal-looking” number sits on reduced function. Read the laboratory-reported eGFR, not the lone creatinine, and verify renally cleared medications were dosed against it.
A rise on an already-reduced baseline
Acute-on-chronic AKI
The highest-risk picture, because reserve was low before the acute hit. Escalate faster. Reconcile for a nephrotoxic stack, trend creatinine and potassium together, and hand over the baseline eGFR at every shift change.
A note on reference ranges: lab reference ranges vary slightly by laboratory and testing program. Always follow the values provided by your facility or testing source. This sheet is for educational NCLEX-RN® preparation and is not medical advice.
