NBME Lab Values Reference Table

Q: Do you get lab values on USMLE Step 1?

Yes. A laboratory reference values table is available during USMLE exams and NBME exams, accessible from the exam interface.

Q: Are the NBME lab values the same for Step 1, Step 2 CK and Step 3?

The NBME publishes one laboratory reference values sheet used across its exams. The values on this page follow the current published version.

Q: Should I memorise normal lab values for Step 1?

Memorising the high-yield values – electrolytes, kidney function, glucose, calcium, CBC, coagulation and ABG – saves time. Rarer values can be looked up.

Q: Is the NBME lab sheet the same as real clinical ranges?

No. The sheet is simplified for exams. Real laboratories use their own reference intervals, and some tests, such as HbA1c and LDL, are interpreted with guideline thresholds.

Q: What is the normal anion gap on the NBME?

The anion gap is not listed on the sheet; it is calculated as Na − (Cl + HCO₃). With NBME values, a typical gap is about 8–12 mEq/L.

Q: What is the NBME normal range for HbA1c?

The sheet lists HbA1c as ≤ 6% (≤ 42 mmol/mol). Clinically, the ADA defines 5.7–6.4% as prediabetes and 6.5% or more as diabetes – see the [A1C calculator](/a1c-calculator).

Q: Are the NBME values in SI units too?

Yes, for most tests. The NBME sheet lists most analytes in conventional (US) units with SI equivalents alongside, so you can practise reading both systems, which is useful if you plan to train or work outside the US. The [lab unit converter](/lab-unit-converter) shows the conversion factors.

Q: What BMI does the NBME list as normal?

Adult 19–25 kg/m². The WHO definition of a normal BMI is 18.5–24.9 kg/m² – see the [BMI calculator](/bmi-calculator).

By AskDr Editorial Team · Medically reviewed against cited guidelines · Last reviewed October 15, 2026

Filter the NBME laboratory reference values by test or section. Values are transcribed from the NBME Laboratory Reference Values document (April 2026) in both conventional and SI units.

Filter

NBME laboratory reference values (conventional and SI units)
Section	Test	Reference range	SI reference interval
Serum – electrolytes	Sodium (Na⁺)	136–146 mEq/L	136–146 mmol/L
Serum – electrolytes	Potassium (K⁺)	3.5–5.0 mEq/L	3.5–5.0 mmol/L
Serum – electrolytes	Chloride (Cl⁻)	95–105 mEq/L	95–105 mmol/L
Serum – electrolytes	Bicarbonate (HCO₃⁻)	22–28 mEq/L	22–28 mmol/L
Serum – general chemistry	Urea nitrogen	7–18 mg/dL	2.5–6.4 mmol/L
Serum – general chemistry	Creatinine	0.6–1.2 mg/dL	53–106 µmol/L
Serum – general chemistry	Glucose, fasting	70–100 mg/dL	3.8–5.6 mmol/L
Serum – general chemistry	Glucose, random (non-fasting)	<140 mg/dL	<7.77 mmol/L
Serum – general chemistry	Calcium	8.4–10.2 mg/dL	2.1–2.6 mmol/L
Serum – general chemistry	Magnesium (Mg²⁺)	1.5–2.0 mg/dL	0.75–1.0 mmol/L
Serum – general chemistry	Phosphorus (inorganic)	3.0–4.5 mg/dL	1.0–1.5 mmol/L
Serum – hepatic	Alanine aminotransferase (ALT)	10–40 U/L	10–40 U/L
Serum – hepatic	Aspartate aminotransferase (AST)	12–38 U/L	12–38 U/L
Serum – hepatic	Alkaline phosphatase	25–100 U/L	25–100 U/L
Serum – hepatic	Bilirubin, total	0.1–1.0 mg/dL	2–17 µmol/L
Serum – hepatic	Bilirubin, direct	0.0–0.3 mg/dL	0–5 µmol/L
Serum – hepatic	Proteins, total	6.0–7.8 g/dL	60–78 g/L
Serum – hepatic	Albumin	3.5–5.5 g/dL	35–55 g/L
Serum – hepatic	Globulin	2.3–3.5 g/dL	23–35 g/L
Serum – other	Amylase	25–125 U/L	25–125 U/L
Serum – other	Lipase	13–60 U/L	13–60 U/L
Serum – other	Creatinine clearance	Male 97–137 mL/min; female 88–128 mL/min	Same
Serum – other	Creatine kinase	Male 25–90 U/L; female 10–70 U/L	Same
Serum – other	Lactate dehydrogenase	45–200 U/L	45–200 U/L
Serum – other	Osmolality	275–295 mOsmol/kg H₂O	275–295 mOsmol/kg H₂O
Serum – other	Troponin I	≤0.04 ng/mL	≤0.04 µg/L
Serum – other	Uric acid	3.0–8.2 mg/dL	0.18–0.48 mmol/L
Lipids	Total cholesterol	Normal <200 mg/dL; high >240 mg/dL	<5.2 mmol/L; >6.2 mmol/L
Lipids	HDL cholesterol	40–60 mg/dL	1.0–1.6 mmol/L
Lipids	LDL cholesterol	<160 mg/dL	<4.2 mmol/L
Lipids	Triglycerides	Normal <150 mg/dL; borderline 151–199 mg/dL	<1.70 mmol/L; 1.71–2.25 mmol/L
Iron studies	Ferritin	Male 20–250 ng/mL; female 10–120 ng/mL	Male 20–250 µg/L; female 10–120 µg/L
Iron studies	Iron	Male 65–175 µg/dL; female 50–170 µg/dL	Male 11.6–31.3 µmol/L; female 9.0–30.4 µmol/L
Iron studies	Total iron-binding capacity	250–400 µg/dL	44.8–71.6 µmol/L
Iron studies	Transferrin	200–360 mg/dL	2.0–3.6 g/L
Endocrine	Follicle-stimulating hormone	Male 4–25 mIU/mL; female premenopause 4–30, midcycle peak 10–90, postmenopause 40–250 mIU/mL	Same values in IU/L
Endocrine	Luteinizing hormone	Male 6–23 mIU/mL; female follicular 5–30, midcycle 75–150, postmenopause 30–200 mIU/mL	Same values in IU/L
Endocrine	Growth hormone – arginine stimulation	Fasting <5 ng/mL; provocative stimuli >7 ng/mL	<5 µg/L; >7 µg/L
Endocrine	Prolactin (hPRL)	Male <17 ng/mL; female <25 ng/mL	<17 µg/L; <25 µg/L
Endocrine	Cortisol	0800 h 5–23 µg/dL; 1600 h 3–15 µg/dL; 2000 h <50% of 0800 h	138–635 nmol/L; 82–413 nmol/L; fraction of 0800 h <0.50
Endocrine	TSH	0.4–4.0 µU/mL	0.4–4.0 mIU/L
Endocrine	Triiodothyronine (T3) (RIA)	100–200 ng/dL	1.5–3.1 nmol/L
Endocrine	T3 resin uptake	25%–35%	0.25–0.35
Endocrine	Thyroxine (T4)	5–12 µg/dL	64–155 nmol/L
Endocrine	Free T4	0.9–1.7 ng/dL	12.0–21.9 pmol/L
Endocrine	Thyroidal iodine (¹²³I) uptake	8%–30% of administered dose/24 h	0.08–0.30/24 h
Endocrine	Intact PTH	10–60 pg/mL	10–60 ng/L
Endocrine	17-Hydroxycorticosteroids (urine)	Male 3.0–10.0 mg/24 h; female 2.0–8.0 mg/24 h	Male 8.2–27.6 µmol/24 h; female 5.5–22.0 µmol/24 h
Endocrine	17-Ketosteroids, total (urine)	Male 8–20 mg/24 h; female 6–15 mg/24 h	Male 28–70 µmol/24 h; female 21–52 µmol/24 h
Immunoglobulins	IgA	76–390 mg/dL	0.76–3.90 g/L
Immunoglobulins	IgE	0–380 IU/mL	0–380 kIU/L
Immunoglobulins	IgG	650–1500 mg/dL	6.5–15.0 g/L
Immunoglobulins	IgM	50–300 mg/dL	0.5–3.0 g/L
Arterial blood gases (room air)	PO₂	75–105 mm Hg	10.0–14.0 kPa
Arterial blood gases (room air)	PCO₂	33–45 mm Hg	4.4–5.9 kPa
Arterial blood gases (room air)	pH	7.35–7.45	[H⁺] 36–44 nmol/L
Cerebrospinal fluid	Cell count	0–5/mm³	0–5 × 10⁶/L
Cerebrospinal fluid	Chloride	118–132 mEq/L	118–132 mmol/L
Cerebrospinal fluid	Gamma globulin	3%–12% total proteins	0.03–0.12
Cerebrospinal fluid	Glucose	40–70 mg/dL	2.2–3.9 mmol/L
Cerebrospinal fluid	Pressure	70–180 mm H₂O	70–180 mm H₂O
Cerebrospinal fluid	Proteins, total	<40 mg/dL	<0.40 g/L
Hematologic – CBC	Hematocrit	Male 41%–53%; female 36%–46%	Male 0.41–0.53; female 0.36–0.46
Hematologic – CBC	Hemoglobin, blood	Male 13.5–17.5 g/dL; female 12.0–16.0 g/dL	Male 135–175 g/L; female 120–160 g/L
Hematologic – CBC	Mean corpuscular hemoglobin (MCH)	25–35 pg/cell	0.39–0.54 fmol/cell
Hematologic – CBC	Mean corpuscular hemoglobin concentration (MCHC)	31%–36% Hb/cell	4.8–5.6 mmol Hb/L
Hematologic – CBC	Mean corpuscular volume (MCV)	80–100 µm³	80–100 fL
Hematologic – CBC	Plasma volume	Male 25–43 mL/kg; female 28–45 mL/kg	Male 0.025–0.043 L/kg; female 0.028–0.045 L/kg
Hematologic – CBC	Red cell volume	Male 20–36 mL/kg; female 19–31 mL/kg	Male 0.020–0.036 L/kg; female 0.019–0.031 L/kg
Hematologic – CBC	Leukocyte count (WBC)	4500–11,000/mm³	4.5–11.0 × 10⁹/L
Hematologic – CBC	Neutrophils, segmented	54%–62%	0.54–0.62
Hematologic – CBC	Neutrophils, bands	3%–5%	0.03–0.05
Hematologic – CBC	Lymphocytes	25%–33%	0.25–0.33
Hematologic – CBC	Monocytes	3%–7%	0.03–0.07
Hematologic – CBC	Eosinophils	1%–3%	0.01–0.03
Hematologic – CBC	Basophils	0%–0.75%	0.00–0.0075
Hematologic – CBC	Platelet count	150,000–400,000/mm³	150–400 × 10⁹/L
Hematologic – coagulation	Partial thromboplastin time (activated)	25–40 seconds	25–40 seconds
Hematologic – coagulation	Prothrombin time (PT)	11–15 seconds	11–15 seconds
Hematologic – coagulation	D-dimer	≤250 ng/mL	≤1.4 nmol/L
Hematologic – other	Reticulocyte count	0.5%–1.5%	0.005–0.015
Hematologic – other	Erythrocyte count (RBC)	Male 4.3–5.9 million/mm³; female 3.5–5.5 million/mm³	Male 4.3–5.9 × 10¹²/L; female 3.5–5.5 × 10¹²/L
Hematologic – other	Erythrocyte sedimentation rate (Westergren)	Male 0–15 mm/h; female 0–20 mm/h	Same
Hematologic – other	CD4⁺ T-lymphocyte count	≥500/mm³	≥0.5 × 10⁹/L
Hematologic – endocrine	Hemoglobin A1c	≤6%	≤42 mmol/mol
Urine	Calcium	100–300 mg/24 h	2.5–7.5 mmol/24 h
Urine	Osmolality	50–1200 mOsmol/kg H₂O	50–1200 mOsmol/kg H₂O
Urine	Oxalate	8–40 µg/mL	90–445 µmol/L
Urine	Proteins, total	<150 mg/24 h	<0.15 g/24 h
Body mass index	BMI (adult)	19–25 kg/m²	19–25 kg/m²

On this page

About the NBME lab values sheet
How the NBME sheet is organised
The high-yield values to know by heart
Unit traps on exam questions
Calculations that build on NBME values
Classic lab patterns worth recognising
How exam ranges differ from real-world ranges
Exam-day tips for using the lab values
Frequently asked questions

About the NBME lab values sheet

The NBME Laboratory Reference Values sheet is the standard table of "normal" lab values provided during USMLE Step 1, Step 2 CK and Step 3, NBME subject (shelf) exams and NBME self-assessments. Whenever a question gives you a laboratory result, you can open the lab values reference to compare it with the range – so knowing how the sheet is laid out and which values matter most saves real time on exam day.

The searchable table above reproduces the values from the NBME's current published sheet (April 2026 version) in both conventional (US) units and SI units. Type any analyte – "ferritin", "PTT", "CSF glucose", "cortisol" – to filter instantly. Below, you will find how the sheet is organised, which ranges are most worth memorising, common traps with units, and how the NBME ranges compare with what you will see on real clinical reports.

Important: these are exam reference values. Real laboratories set their own reference intervals, which can differ. For interpreting your own blood test, use the range on your report – our how to read a blood test guide explains how.

How the NBME sheet is organised

The sheet groups analytes by specimen and system. Knowing the order means you can jump straight to the right section:

Section	What it contains	Examples
Serum – general chemistry	Electrolytes, kidney, glucose, minerals	Na, K, Cl, HCO₃, BUN, creatinine, glucose, Ca, Mg, phosphorus
Serum – hepatic	Liver enzymes and proteins	ALT, AST, ALP, bilirubin, total protein, albumin, globulin
Serum – other	Pancreas, muscle, misc.	Amylase, lipase, CK, LDH, osmolality, troponin I, uric acid, creatinine clearance
Lipids	Cholesterol fractions	Total, HDL, LDL, triglycerides
Iron studies	Iron panel	Ferritin, iron, TIBC, transferrin
Endocrine	Pituitary, thyroid, adrenal, PTH	FSH, LH, prolactin, cortisol, TSH, T3, T4, free T4, PTH
Immunoglobulins	IgA, IgE, IgG, IgM
Arterial blood gases	Room air	pH, Pco₂, Po₂
Cerebrospinal fluid	Lumbar puncture	Cell count, glucose, protein, pressure
Haematologic	CBC and differential, volumes	Hb, Hct, MCV, MCH, MCHC, WBC, differential, platelets
Coagulation and other haematologic	Clotting, reticulocytes, ESR	PT, PTT, D-dimer, reticulocyte count, RBC count, ESR, CD4
Urine and BMI	24-hour urine values, BMI	Urine calcium, osmolality, oxalate, protein; adult BMI

The high-yield values to know by heart

You can always look values up, but every click costs time – and many questions hinge on recognising an abnormal value instantly. These are the ranges most worth memorising:

Analyte	NBME range	Why it is high-yield
Sodium	136–146 mEq/L	Hypo/hypernatraemia, SIADH, diabetes insipidus
Potassium	3.5–5.0 mEq/L	ECG changes, renal tubular acidosis, diuretics
Chloride	95–105 mEq/L	Anion gap, contraction alkalosis
Bicarbonate	22–28 mEq/L	Acid–base questions
BUN	7–18 mg/dL	Pre-renal vs intrinsic AKI (BUN/Cr ratio)
Creatinine	0.6–1.2 mg/dL	Kidney function
Glucose (fasting)	70–100 mg/dL	Diabetes, hypoglycaemia, insulinoma
Calcium	8.4–10.2 mg/dL	Hyperparathyroidism, malignancy
Magnesium	1.5–2.0 mg/dL	Refractory hypokalaemia
Phosphorus	3.0–4.5 mg/dL	CKD-mineral bone disease, hypoparathyroidism
ALT / AST	10–40 / 12–38 U/L	Hepatitis patterns, AST:ALT ratio
Haemoglobin	M 13.5–17.5 / F 12.0–16.0 g/dL	Anaemia
MCV	80–100 fL	Classifying anaemia
WBC	4,500–11,000/mm³	Infection, leukaemia
Platelets	150,000–400,000/mm³	ITP, TTP, HIT, DIC
PT / PTT	11–15 / 25–40 s	Coagulation pathway questions
ABG pH / Pco₂	7.35–7.45 / 33–45 mm Hg	Acid–base compensation
TSH	0.4–4.0 µU/mL	Thyroid disease
HbA1c	≤ 6%	Diabetes

A good habit is to know these well enough that you only open the sheet for less common values – CSF, immunoglobulins, urine studies and hormones.

Unit traps on exam questions

Most USMLE questions use conventional units, but values are sometimes given in SI units, and the sheet shows both. Common pitfalls:

Haemoglobin in g/L vs g/dL – 120 g/L is 12.0 g/dL.
Glucose in mmol/L – multiply by about 18 to get mg/dL (5.6 mmol/L ≈ 100 mg/dL).
Creatinine in µmol/L – divide by 88.4 to get mg/dL (106 µmol/L ≈ 1.2 mg/dL).
Blood gases in kPa – multiply by 7.5 to get mm Hg (5.3 kPa ≈ 40 mm Hg).
WBC and platelets – "/mm³" and "× 10⁹/L" differ by a factor of 1,000: 11,000/mm³ = 11.0 × 10⁹/L.
TSH – µU/mL and mIU/L are numerically identical.

If you want to practise conversions, the lab unit converter and mg/dL to mmol/L converter cover the main analytes, and the mg/dL to µmol/L converter handles creatinine, uric acid and bilirubin.

Calculations that build on NBME values

Several exam favourites are derived from values on the sheet rather than listed on it:

Calculation	Formula	Normal	Tool
Anion gap	Na − (Cl + HCO₃)	About 8–12 mEq/L	Anion gap calculator
Serum osmolality	2 × Na + glucose/18 + BUN/2.8	275–295 mOsm/kg	Osmolality calculator
Corrected calcium	Ca + 0.8 × (4 − albumin)	8.4–10.2 mg/dL	Corrected calcium
BUN/creatinine ratio	BUN ÷ Cr	About 10–20	BUN/creatinine ratio
Corrected sodium (hyperglycaemia)	Na + 1.6 to 2.4 × (glucose − 100)/100	–	Corrected sodium
Transferrin saturation	Iron ÷ TIBC × 100	About 20–50%	TIBC blood test
QTc	QT ÷ √RR (Bazett)	Under about 450 ms (men), 460 ms (women)	QTc calculator
A–a gradient	PAo₂ − Pao₂	Rises with age	–

Classic lab patterns worth recognising

Many exam questions hinge on a combination of values rather than any single result. A few classic patterns that use the ranges on the sheet:

Pattern	Key values	Typical association
High anion gap metabolic acidosis	Low HCO₃, gap above about 12	Ketoacidosis, lactic acidosis, kidney failure, toxic alcohols, salicylates
Contraction (metabolic) alkalosis	High HCO₃, low Cl, low K	Vomiting, diuretics
SIADH	Low Na, low serum osmolality, inappropriately concentrated urine	Small-cell lung cancer, CNS disease, some medicines
Primary hyperparathyroidism	High Ca, high or inappropriately normal PTH, low phosphorus	Parathyroid adenoma
Microcytic anaemia with low ferritin	Low Hb, MCV under 80, low ferritin, high TIBC	Iron deficiency
Haemolysis	Low Hb, high reticulocytes, high LDH, high indirect bilirubin	Autoimmune, G6PD, hereditary spherocytosis
Isolated prolonged PT	PT above 15 s, normal PTT	Warfarin, early vitamin K deficiency, liver disease
Isolated prolonged PTT	PTT above 40 s, normal PT	Haemophilia A/B, heparin, lupus anticoagulant
Bacterial meningitis CSF	High cells (neutrophils), low glucose, high protein	Compare with CSF reference values

Recognising these combinations quickly is far more valuable than recalling an isolated number.

How exam ranges differ from real-world ranges

The NBME values are designed to be consistent, simple and stable across exams. Real laboratories differ in several ways:

Analyte	NBME sheet	Common clinical practice	Note
Creatinine	0.6–1.2 mg/dL (single range)	Sex-specific ranges (e.g. MedlinePlus 0.7–1.3 men, 0.5–0.95 women)	eGFR is used clinically
HbA1c	≤ 6%	Under 5.7% normal; 5.7–6.4% prediabetes; 6.5%+ diabetes (ADA)	Diagnostic thresholds
LDL	< 160 mg/dL	Risk-based targets	Guidelines use overall cardiovascular risk
Ferritin (women)	10–120 ng/mL	Many clinicians treat under 30 as iron deficiency	Thresholds vary by context
TSH	0.4–4.0	Upper limits up to 4.5–5.0; age-dependent	Pregnancy uses trimester ranges
Troponin I	≤ 0.04 ng/mL	High-sensitivity assays with sex-specific 99th centiles in ng/L	Assay-dependent
BMI	Adult 19–25 kg/m²	WHO normal 18.5–24.9 kg/m²	Rounded on the sheet

So for clinical work, always use your local laboratory's ranges and current guidelines. For exams, use the sheet.

Exam-day tips for using the lab values

Practise with the sheet open during question banks so you know where each value sits.
Learn the high-yield ranges above so you only need the sheet for rarer values.
Use the search box on the exam interface rather than scrolling; on this page, the search above behaves similarly.
Read the units in the question stem before comparing with the sheet.
Do not over-interpret borderline values – exam questions usually make significant abnormalities obvious.
Remember derived values: an anion gap or A–a gradient is rarely given directly.

Frequently asked questions

Do you get lab values on USMLE Step 1?

Yes. A laboratory reference values table is available during USMLE exams and NBME exams, accessible from the exam interface.

Are the NBME lab values the same for Step 1, Step 2 CK and Step 3?

The NBME publishes one laboratory reference values sheet used across its exams. The values on this page follow the current published version.

Should I memorise normal lab values for Step 1?

Memorising the high-yield values – electrolytes, kidney function, glucose, calcium, CBC, coagulation and ABG – saves time. Rarer values can be looked up.

Is the NBME lab sheet the same as real clinical ranges?

No. The sheet is simplified for exams. Real laboratories use their own reference intervals, and some tests, such as HbA1c and LDL, are interpreted with guideline thresholds.

What is the normal anion gap on the NBME?