The Top 100 NCLEX Lab Values You Must Memorize in 2026

Lab values show up on nearly every NCLEX-RN. You do not need to memorize 400 ranges — focus on the 100 that appear most often. This cheat sheet is organized by system so you can drill in 15-minute blocks.

Electrolytes (highest yield)

Sodium 135–145 mEq/L. Potassium 3.5–5.0 mEq/L. Calcium 8.5–10.5 mg/dL. Magnesium 1.5–2.5 mEq/L. These four alone appear in dozens of prioritization questions — critical highs and lows are the fastest way to identify an unstable client.

Arterial blood gases

pH 7.35–7.45. PaCO₂ 35–45. HCO₃ 22–26. PaO₂ 80–100. SaO₂ 95–100%. Learn the Tic-Tac-Toe method (linked in our ABG article) to name respiratory vs metabolic, compensated vs uncompensated in under 20 seconds.

Kidney panel

BUN 10–20 mg/dL. Creatinine 0.6–1.2 mg/dL. GFR ≥ 90. A rising creatinine on the NCLEX almost always means hold nephrotoxic meds (aminoglycosides, contrast dye, NSAIDs) and notify the provider.

Anticoagulation

INR 0.9–1.2 normal, 2.0–3.0 therapeutic for most warfarin indications. aPTT 30–40 seconds normal, 1.5–2× control for therapeutic heparin. Platelets 150k–400k. Below 50k = bleeding precautions, below 20k = spontaneous bleeding risk.

Drug levels

Digoxin 0.5–2.0 ng/mL. Lithium 0.6–1.2 mEq/L. Phenytoin 10–20 mcg/mL. Vancomycin trough 10–20 mcg/mL. Above therapeutic = hold and call.

Cardiac markers

Troponin < 0.04 ng/mL. BNP < 100 pg/mL (heart failure). If troponin rises with chest pain — treat as MI.

The full 100-lab printable is inside the NCLEXVault dashboard. Every value is paired with the nursing action NCLEX expects you to take.

Why Lab Values are Your Secret Weapon on the Next-Gen NCLEX

Welcome back, future nurses! When you sit down for your exam, you will quickly realize that NCLEX lab values are not just random numbers you need to memorize for a matching game. The Next-Generation NCLEX focuses heavily on your clinical judgment, which means you must interpret these values within realistic patient scenarios. Whether you are analyzing a client with worsening heart failure or evaluating a child with severe dehydration, these numbers guide your immediate nursing interventions. Do not let the massive list of values overwhelm you. We have broken down the most crucial nursing lab values so you can build a solid foundation and confidently tackle those complex case studies.

Mastering the Electrolytes: Potassium and Sodium

Let us start with the heavy hitters of the fluid and electrolyte world. Potassium is your absolute priority because even tiny fluctuations outside the normal range of 3.5 to 5.0 mEq/L can trigger lethal cardiac arrhythmias. If you see a patient on furosemide with a potassium level of 2.8, your nursing intuition should immediately scream hypokalemia, prompting you to check for flat T-waves and muscle weakness. On the flip side, sodium levels, which should sit comfortably between 135 and 145 mEq/L, primarily affect the central nervous system. When a client presents with severe hyponatremia below 120, you need to implement seizure precautions and monitor their neurological status closely.

Renal Function Markers: BUN and Creatinine

When you are assessing kidney function on the exam, you must always look at blood urea nitrogen and serum creatinine together. Serum creatinine, with a normal range of 0.6 to 1.2 mg/dL, is the highly specific golden standard for renal clearance because it only rises when the kidneys are genuinely struggling. On the other hand, blood urea nitrogen, or BUN, normally ranges from 10 to 20 mg/dL and can easily fluctuate based on dehydration, high-protein diets, or gastrointestinal bleeding. If you see an isolated high BUN with a perfectly normal creatinine, think dehydration first. However, if both numbers are soaring, your patient is likely experiencing acute kidney injury or chronic renal failure, which requires immediate medical intervention.

Hematology Essentials: Decoding the Complete Blood Count

The complete blood count is a staple of daily nursing practice, and the NCLEX expects you to know exactly when to worry. For white blood cells, the standard range is 5,000 to 10,000 cells/mm3, and a drop below 4,000 should immediately put your neutropenic precautions plan into action. When evaluating red blood cells, keep your eyes on hemoglobin, which ranges from 12 to 18 g/dL depending on biological sex, and hematocrit, which sits between 37 percent and 52 percent. If these hematology markers plummet, your patient is at risk for tissue hypoxia, so watch for fatigue and shortness of breath. Finally, platelets must range from 150,000 to 400,000; anything under 50,000 puts your patient at severe risk for spontaneous bleeding.

Coagulation Panels and Medication Safety

Understanding coagulation times is crucial for safe medication administration, making these numbers some of the most tested nursing lab values on the board. When your patient is on a continuous heparin infusion for a deep vein thrombosis, you must monitor the activated partial thromboplastin time, aiming for a therapeutic range of 46 to 70 seconds. For patients taking oral warfarin, you will instead track the international normalized ratio, where a therapeutic target is typically 2.0 to 3.0. Always keep the respective antidotes in mind while reviewing these labs, specifically protamine sulfate for heparin and vitamin K for warfarin. If an exam question presents an INR of 5.5, your immediate nursing action is to hold the drug and assess for bleeding.

Navigating Arterial Blood Gases Without the Confusion

Arterial blood gas interpretation can feel intimidating, but you can master it by remembering a few key reference points. First, memorize the normal pH of 7.35 to 7.45, where anything lower is acidic and anything higher is alkalotic. Next, look at carbon dioxide, managed by the lungs, which should range from 35 to 45 mmHg, and bicarbonate, regulated by the kidneys, which ranges from 22 to 26 mEq/L. If you encounter a COPD patient with a pH of 7.31 and a carbon dioxide level of 52, you should quickly identify respiratory acidosis. Understanding these relationships allows you to anticipate whether a patient needs oxygen therapy, mechanical ventilation adjustments, or sodium bicarbonate administration.

Hepatic and Pancreatic Enzymes: Assessing the Abdomen

When a patient presents with severe abdominal pain, you need to look at specific liver and pancreatic enzymes to locate the source of the problem. Liver function is primarily assessed using alanine aminotransferase and aspartate aminotransferase, which should both remain under 40 units per liter. Significantly elevated liver enzymes often point to hepatitis or drug-induced toxicity from medications like acetaminophen. Meanwhile, if you suspect acute pancreatitis, you must evaluate amylase and lipase. Lipase is the more specific marker for pancreatic damage, and levels that exceed three times the normal limit of 160 units per liter confirm active inflammation. Your immediate nursing priorities here will involve keeping the patient strictly nothing by mouth and managing their severe pain.

Cardiac Markers and Glycemic Control

To round out your ultimate NCLEX cheat sheet, you must memorize critical cardiac markers and long-term metabolic indicators. When a patient reports crushing chest pain, troponin is your go-to diagnostic lab, as any value above 0.03 ng/mL suggests myocardial injury. For long-term diabetic management, look past daily fingersticks and evaluate the glycated hemoglobin, or HbA1c, which should ideally remain below 7 percent for diabetic patients. A high HbA1c indicates poor glycemic control over the past three months, prompting you to educate the patient on diet and insulin compliance. Memorizing these distinct values ensures you can quickly differentiate an acute cardiac emergency from chronic metabolic issues during your exam.

Managing Narrow Therapeutic Drug Levels

Some medications have incredibly narrow safety margins, meaning you must monitor their serum levels meticulously to prevent severe toxicity. For example, digoxin, a common cardiac glycoside, has a narrow therapeutic range of 0.5 to 2.0 ng/mL, and toxicity often manifests as bradycardia and visual halos. Similarly, lithium, used for bipolar disorder, must be kept between 0.6 and 1.2 mEq/L to prevent neurological damage. Dilantin, an anticonvulsant, requires blood levels of 10 to 20 mcg/mL to effectively prevent seizures without causing toxicity. When you see these drugs on your exam, always check the lab results first to ensure your patient is in the safe zone before administering the next dose.