NCLEX lab values cheat sheet
Searchable NCLEX lab values: electrolytes, CBC, coagulation, ABGs, renal and therapeutic drug levels, with nursing pearls and a quick quiz to lock them in.
These are standard, widely taught adult reference ranges. Every laboratory sets its own ranges, so books and facilities differ slightly. In clinical practice, always use your facility's values.
Electrolytes
Low sodium can cause confusion and seizures. Correct it slowly.
Either direction can cause dysrhythmias. Never give IV potassium by IV push.
Usually moves with sodium.
Low calcium: tetany, positive Chvostek and Trousseau signs. Some labs use 8.5–10.5.
Some labs report 1.5–2.5 mg/dL. Watch reflexes and respirations with IV magnesium.
Moves opposite to calcium. Often high in chronic kidney disease.
Blood counts
Female range is about 12–16 g/dL.
Ranges are lower in pregnancy.
Roughly three times the hemoglobin. Rises with dehydration.
Falls with bleeding or fluid overload.
Low WBC: neutropenic precautions. Some labs use 4,500–11,000.
Low platelets: bleeding precautions, soft toothbrush, no IM injections when possible.
Coagulation
Monitors warfarin, together with the INR.
On warfarin the usual target is about 2–3 (higher for some valves). Antidote: vitamin K.
Monitors IV heparin; therapeutic is often 1.5–2.5 times control. Antidote: protamine.
ABGs
Below 7.35 is acidosis, above 7.45 is alkalosis.
The respiratory part. High CO2 = respiratory acidosis.
The metabolic part. Low bicarbonate = metabolic acidosis.
Ranges are lower for older adults.
Targets may be lower in COPD, as ordered.
Renal & metabolic
Under 70 is hypoglycemia: treat with fast-acting carbohydrate if the client can swallow. Many NCLEX books use 70–110.
Reflects about 3 months of glucose. 6.5% or higher is in the diabetes range.
Rises with dehydration and kidney injury.
The best routine marker of kidney function. Slightly lower in females.
Low albumin points to poor nutrition or liver disease, and causes edema.
High = concentrated urine (dehydration). Low = dilute.
Drug levels
Toxicity: nausea, vision changes (yellow-green halos), bradycardia. Low potassium raises the risk.
Narrow range. Dehydration and low sodium push levels up.
Toxicity: nystagmus, ataxia, slurred speech. Gingival hyperplasia with long-term use.
Toxicity: tachycardia, restlessness, seizures. Many references now aim lower (5–15).
Is it low, normal or high? Five random labs, about a minute.
How to learn lab values for the NCLEX
You don't need every lab in the hospital. NCLEX questions lean on a high-yield set: the electrolytes, blood counts, coagulation studies, ABGs, kidney function and a handful of drugs with narrow therapeutic ranges. Those are the ones on this page.
Memorizing the number is only half the job. The exam rarely asks "what's the normal sodium?". It asks what you'd do when the value is off: which finding to expect, which order to question, which client to see first. So learn each lab as a pair: the range, and the nursing action when it's high or low.
Three patterns worth knowing cold
- Potassium and the heart. High or low, potassium changes the cardiac rhythm, which is why abnormal potassium values are so often the priority.
- Anticoagulant monitoring. PT/INR goes with warfarin (antidote vitamin K); aPTT goes with IV heparin (antidote protamine).
- Narrow-range drugs. Digoxin and lithium have small gaps between helpful and toxic, and dehydration or electrolyte shifts can push a stable client into toxicity.
Quiz yourself instead of rereading
Reading this table feels productive, but retrieval practice beats rereading for long-term memory. Use the quick quiz above a few times a week: each round picks five random labs and a value that's low, normal or high. Saying "high potassium, peaked T waves, cardiac monitor" out loud after each answer turns a number into something you can use on the exam. For the science behind this, see Stop rereading: 3 study techniques with real science.
Frequently asked questions
Which lab values do I need to memorize for the NCLEX?
Focus on the high-yield set: sodium, potassium, calcium, magnesium, glucose, BUN and creatinine, hemoglobin and hematocrit, WBC, platelets, PT/INR and aPTT, ABGs, and the therapeutic ranges for drugs like digoxin and lithium.
Why do lab value ranges differ between books?
Every laboratory sets its own reference ranges based on its equipment and methods, so textbooks and facilities differ slightly. On the exam, values far outside the range are what matter, and questions usually give enough context. In practice, always use your facility's ranges.
What's the best way to memorize lab values?
Quiz yourself instead of rereading the table. Retrieval practice, spaced over several days, works better than reviewing a chart. Pair each value with what you'd do as the nurse if it were high or low.
For study purposes only. Always follow your program, your facility's policies and your board of nursing. Mars AI isn't affiliated with NCSBN.