Comprehensive Laboratory Values Reference Guide: The Ultimate Clinical Cheatsheet

Cheatsheets

Introduction

Laboratory tests provide critical information for screening, diagnosis, and monitoring of diseases and treatment effectiveness. This reference guide summarizes common laboratory values and their typical ranges to assist healthcare professionals and patients in interpreting test results. Remember that reference ranges may vary slightly between laboratories, and some values require clinical context for proper interpretation.

Complete Blood Count (CBC)

TestConventional UnitsSI UnitsNotes
Red Blood Cell (RBC) Count   
Adult Males4.5-5.9 × 10^6/μL4.5-5.9 × 10^12/L 
Adult Females4.0-5.2 × 10^6/μL4.0-5.2 × 10^12/L 
Hemoglobin (Hgb)   
Adult Males13.5-17.5 g/dL135-175 g/L 
Adult Females12.0-15.5 g/dL120-155 g/L 
Pregnant Females11.0-14.0 g/dL110-140 g/L 
Hematocrit (Hct)   
Adult Males41-50%0.41-0.50 
Adult Females36-46%0.36-0.46 
Mean Corpuscular Volume (MCV)80-100 fL80-100 fL 
Mean Corpuscular Hemoglobin (MCH)27-33 pg27-33 pg 
Mean Corpuscular Hemoglobin Concentration (MCHC)32-36 g/dL320-360 g/L 
Red Cell Distribution Width (RDW)11.5-14.5%11.5-14.5% 
Platelet Count150-450 × 10^3/μL150-450 × 10^9/L 
Mean Platelet Volume (MPV)7.5-11.5 fL7.5-11.5 fL 
White Blood Cell (WBC) Count4.5-11.0 × 10^3/μL4.5-11.0 × 10^9/L 
WBC Differential   
Neutrophils40-75%0.40-0.75Absolute: 1.8-7.7 × 10^3/μL
Lymphocytes20-45%0.20-0.45Absolute: 1.0-4.8 × 10^3/μL
Monocytes2-10%0.02-0.10Absolute: 0.2-0.8 × 10^3/μL
Eosinophils1-6%0.01-0.06Absolute: 0.05-0.5 × 10^3/μL
Basophils0-2%0.00-0.02Absolute: 0.02-0.1 × 10^3/μL

Basic Metabolic Panel (BMP)

TestConventional UnitsSI UnitsNotes
Glucose (Fasting)70-99 mg/dL3.9-5.5 mmol/LPrediabetes: 100-125 mg/dL<br>Diabetes: ≥126 mg/dL
Electrolytes   
Sodium (Na+)135-145 mEq/L135-145 mmol/L 
Potassium (K+)3.5-5.0 mEq/L3.5-5.0 mmol/L 
Chloride (Cl-)98-107 mEq/L98-107 mmol/L 
Bicarbonate (HCO3-)22-29 mEq/L22-29 mmol/L 
Kidney Function   
Blood Urea Nitrogen (BUN)7-20 mg/dL2.5-7.1 mmol/L 
Creatinine   
Adult Males0.7-1.3 mg/dL62-115 μmol/L 
Adult Females0.6-1.1 mg/dL53-97 μmol/L 
eGFR≥60 mL/min/1.73m²≥60 mL/min/1.73m²Values <60 may indicate kidney disease
BUN/Creatinine Ratio10:1-20:110:1-20:1 
Calcium   
Total Calcium8.5-10.5 mg/dL2.1-2.6 mmol/L 
Ionized Calcium4.5-5.6 mg/dL1.1-1.4 mmol/L 

Comprehensive Metabolic Panel (CMP)

Includes all BMP tests plus these additional tests:

TestConventional UnitsSI UnitsNotes
Protein   
Total Protein6.0-8.3 g/dL60-83 g/L 
Albumin3.5-5.0 g/dL35-50 g/L 
Globulin2.0-3.5 g/dL20-35 g/L 
Albumin/Globulin Ratio1.2-2.21.2-2.2 
Liver Function   
Total Bilirubin0.1-1.2 mg/dL1.7-20.5 μmol/L 
Direct Bilirubin0.0-0.3 mg/dL0.0-5.1 μmol/L 
Alkaline Phosphatase (ALP)44-147 U/L44-147 U/LRange varies by age
Alanine Aminotransferase (ALT)   
Males7-56 U/L7-56 U/L 
Females7-45 U/L7-45 U/L 
Aspartate Aminotransferase (AST)   
Males8-48 U/L8-48 U/L 
Females8-43 U/L8-43 U/L 

Lipid Panel

TestConventional UnitsSI UnitsInterpretation
Total Cholesterol   
Desirable<200 mg/dL<5.18 mmol/L 
Borderline High200-239 mg/dL5.18-6.19 mmol/L 
High≥240 mg/dL≥6.22 mmol/L 
LDL Cholesterol   
Optimal<100 mg/dL<2.59 mmol/L 
Near Optimal100-129 mg/dL2.59-3.34 mmol/L 
Borderline High130-159 mg/dL3.37-4.12 mmol/L 
High160-189 mg/dL4.15-4.90 mmol/L 
Very High≥190 mg/dL≥4.92 mmol/L 
HDL Cholesterol   
Low<40 mg/dL (males)<br><50 mg/dL (females)<1.04 mmol/L (males)<br><1.30 mmol/L (females) 
Optimal≥60 mg/dL≥1.55 mmol/LProtective against heart disease
Triglycerides   
Normal<150 mg/dL<1.70 mmol/L 
Borderline High150-199 mg/dL1.70-2.25 mmol/L 
High200-499 mg/dL2.26-5.64 mmol/L 
Very High≥500 mg/dL≥5.65 mmol/L 
Non-HDL Cholesterol   
Optimal<130 mg/dL<3.37 mmol/L 

Liver Function Tests (LFTs)

TestConventional UnitsSI UnitsNotes
Alanine Aminotransferase (ALT)   
Males7-56 U/L7-56 U/L 
Females7-45 U/L7-45 U/L 
Aspartate Aminotransferase (AST)   
Males8-48 U/L8-48 U/L 
Females8-43 U/L8-43 U/L 
Alkaline Phosphatase (ALP)44-147 U/L44-147 U/LHigher in children and elderly
Gamma-Glutamyl Transferase (GGT)   
Males8-61 U/L8-61 U/L 
Females5-36 U/L5-36 U/L 
Bilirubin   
Total0.1-1.2 mg/dL1.7-20.5 μmol/L 
Direct (Conjugated)0.0-0.3 mg/dL0.0-5.1 μmol/L 
Indirect (Unconjugated)0.1-0.9 mg/dL1.7-15.4 μmol/L 
Albumin3.5-5.0 g/dL35-50 g/L 
Prothrombin Time (PT)11-13.5 seconds11-13.5 seconds 
International Normalized Ratio (INR)0.8-1.10.8-1.12.0-3.0 for patients on warfarin

Kidney Function Tests

TestConventional UnitsSI UnitsNotes
Creatinine   
Adult Males0.7-1.3 mg/dL62-115 μmol/L 
Adult Females0.6-1.1 mg/dL53-97 μmol/L 
Blood Urea Nitrogen (BUN)7-20 mg/dL2.5-7.1 mmol/L 
Estimated Glomerular Filtration Rate (eGFR)   
Normal≥90 mL/min/1.73m²≥90 mL/min/1.73m² 
Mild Decrease60-89 mL/min/1.73m²60-89 mL/min/1.73m² 
Moderate Decrease30-59 mL/min/1.73m²30-59 mL/min/1.73m² 
Severe Decrease15-29 mL/min/1.73m²15-29 mL/min/1.73m² 
Kidney Failure<15 mL/min/1.73m²<15 mL/min/1.73m² 
Urine Studies   
Specific Gravity1.005-1.0301.005-1.030 
pH4.5-8.04.5-8.0 
ProteinNegativeNegative<150 mg/24 hours
GlucoseNegativeNegative 
KetonesNegativeNegative 
Urobilinogen0.1-1.0 EU/dL0.1-1.0 mg/dL 
BilirubinNegativeNegative 
NitritesNegativeNegative 
Leukocyte EsteraseNegativeNegative 
RBCs0-2/HPF0-2/HPF 
WBCs0-5/HPF0-5/HPF 
BacteriaNegativeNegative 
CastsNegative or FewNegative or Few 
24-Hour Urine Collection   
Total Protein<150 mg/24h<0.15 g/24h 
Creatinine Clearance   
Males97-137 mL/min97-137 mL/min 
Females88-128 mL/min88-128 mL/min 

Cardiac Markers

TestConventional UnitsSI UnitsNotes
Troponin I<0.04 ng/mL<0.04 μg/LDependent on assay
Troponin T<0.01 ng/mL<0.01 μg/LDependent on assay
High-Sensitivity Troponin (hs-cTn)   
Males<22 ng/L<22 ng/L 
Females<14 ng/L<14 ng/L 
CK-MB<3.8 ng/mL<3.8 μg/L 
CK Total   
Males39-308 U/L39-308 U/L 
Females26-192 U/L26-192 U/L 
Myoglobin   
Males28-72 ng/mL28-72 μg/L 
Females25-58 ng/mL25-58 μg/L 
B-type Natriuretic Peptide (BNP)<100 pg/mL<100 ng/LValues >400 pg/mL suggest heart failure
NT-proBNP   
<50 years<450 pg/mL<450 ng/L 
50-75 years<900 pg/mL<900 ng/L 
>75 years<1800 pg/mL<1800 ng/L 

Coagulation Studies

TestConventional UnitsSI UnitsNotes
Prothrombin Time (PT)11-13.5 seconds11-13.5 seconds 
International Normalized Ratio (INR)0.8-1.10.8-1.1Target 2.0-3.0 for most conditions requiring warfarin
Partial Thromboplastin Time (PTT)25-35 seconds25-35 seconds 
Activated Partial Thromboplastin Time (aPTT)30-40 seconds30-40 seconds1.5-2.5× normal for heparin therapy
Thrombin Time (TT)14-16 seconds14-16 seconds 
D-dimer<500 ng/mL<500 μg/LValues vary by assay
Fibrinogen200-400 mg/dL2.0-4.0 g/L 
Bleeding Time2-8 minutes2-8 minutes 
Platelet Function80-165 seconds80-165 secondsFor PFA-100 collagen/epinephrine

Endocrine Tests

TestConventional UnitsSI UnitsNotes
Thyroid Function   
TSH0.4-4.0 mIU/L0.4-4.0 mIU/L 
Free T40.8-1.8 ng/dL10-23 pmol/L 
Free T32.3-4.2 pg/mL3.5-6.5 pmol/L 
Total T45.0-12.0 μg/dL64.5-154.4 nmol/L 
Total T380-200 ng/dL1.2-3.1 nmol/L 
Glucose Metabolism   
Fasting Glucose70-99 mg/dL3.9-5.5 mmol/L 
Hemoglobin A1c<5.7%<39 mmol/mol5.7-6.4% prediabetes<br>≥6.5% diabetes
Adrenal Function   
Cortisol (8 AM)5-25 μg/dL138-690 nmol/L 
Cortisol (4 PM)3-12 μg/dL83-331 nmol/L 
ACTH7-63 pg/mL1.5-14 pmol/L 
Aldosterone (upright)7-30 ng/dL0.19-0.83 nmol/L 
Renin Activity (upright)0.5-4.0 ng/mL/h0.13-1.03 ng/L/s 
Reproductive Hormones   
Testosterone (Total)   
Males280-1080 ng/dL9.7-37.5 nmol/L 
Females15-70 ng/dL0.52-2.4 nmol/L 
Free Testosterone   
Males8.7-25.1 pg/mL30-87 pmol/L 
Females0.3-1.9 pg/mL1.0-6.6 pmol/L 
Estradiol   
Males10-40 pg/mL37-147 pmol/L 
Females (Follicular)30-120 pg/mL110-440 pmol/L 
Females (Midcycle)100-400 pg/mL367-1468 pmol/L 
Females (Luteal)50-250 pg/mL184-918 pmol/L 
Females (Postmenopausal)<30 pg/mL<110 pmol/L 
Progesterone   
Males<1.0 ng/mL<3.2 nmol/L 
Females (Follicular)<1.0 ng/mL<3.2 nmol/L 
Females (Luteal)3.0-25.0 ng/mL9.5-79.5 nmol/L 
FSH   
Males1.5-12.4 mIU/mL1.5-12.4 IU/L 
Females (Follicular)3.5-12.5 mIU/mL3.5-12.5 IU/L 
Females (Midcycle)4.7-21.5 mIU/mL4.7-21.5 IU/L 
Females (Luteal)1.7-7.7 mIU/mL1.7-7.7 IU/L 
Females (Postmenopausal)25.8-134.8 mIU/mL25.8-134.8 IU/L 
LH   
Males1.7-8.6 mIU/mL1.7-8.6 IU/L 
Females (Follicular)2.4-12.6 mIU/mL2.4-12.6 IU/L 
Females (Midcycle)14.0-95.6 mIU/mL14.0-95.6 IU/L 
Females (Luteal)1.0-11.4 mIU/mL1.0-11.4 IU/L 
Females (Postmenopausal)7.7-58.5 mIU/mL7.7-58.5 IU/L 
Parathyroid and Bone Metabolism   
Parathyroid Hormone (PTH)15-65 pg/mL1.6-6.9 pmol/L 
25-Hydroxyvitamin D30-100 ng/mL75-250 nmol/L 
Calcium8.5-10.5 mg/dL2.1-2.6 mmol/L 
Phosphorus2.5-4.5 mg/dL0.81-1.45 mmol/L 

Tumor Markers

TestConventional UnitsSI UnitsAssociated Cancers
Alpha-Fetoprotein (AFP)<10 ng/mL<10 μg/LLiver, testicular
Beta-hCG<5 mIU/mL<5 IU/LTesticular, trophoblastic
CA 15-3<30 U/mL<30 kU/LBreast
CA 19-9<37 U/mL<37 kU/LPancreatic, biliary
CA 125<35 U/mL<35 kU/LOvarian
Carcinoembryonic Antigen (CEA)<2.5 ng/mL (non-smokers)<br><5.0 ng/mL (smokers)<2.5 μg/L (non-smokers)<br><5.0 μg/L (smokers)Colorectal, lung, breast
Prostate-Specific Antigen (PSA)   
Total0-4.0 ng/mL0-4.0 μg/LProstate
Free>25% of total>0.25 
Human Epididymis Protein 4 (HE4)<140 pmol/L<140 pmol/LOvarian

Arterial Blood Gas (ABG)

TestReference RangeInterpretation
pH7.35-7.45<7.35: Acidemia<br>>7.45: Alkalemia
PaO280-100 mmHg<60 mmHg: Hypoxemia
PaCO235-45 mmHg<35 mmHg: Hypocapnia<br>>45 mmHg: Hypercapnia
HCO3-22-26 mEq/L<22: Metabolic acidosis<br>>26: Metabolic alkalosis
Base Excess-2 to +2 mEq/L<-2: Base deficit (metabolic acidosis)<br>>+2: Base excess (metabolic alkalosis)
O2 Saturation95-100%<90%: Significant hypoxemia
Anion Gap8-16 mEq/L>16: High anion gap metabolic acidosis

Cerebrospinal Fluid (CSF)

TestReference RangeNotes
AppearanceClear, colorless 
Opening Pressure70-180 mm H2O 
WBCs0-5 cells/μL>5: Inflammation or infection
Protein15-45 mg/dL 
Glucose40-70 mg/dL>60% of serum glucose
Lactate10-20 mg/dL 
Gram StainNo organisms 
CultureNo growth 

Special Considerations

Pediatric Reference Ranges

Many laboratory values vary significantly by age. Consult age-specific reference ranges for:

  • Hemoglobin and hematocrit
  • White blood cell counts
  • Alkaline phosphatase
  • Creatinine
  • Calcium
  • Glucose

Pregnancy Reference Ranges

Several lab values normally change during pregnancy:

  • Increased: WBC, alkaline phosphatase, fibrinogen, factors VII, VIII, IX, X
  • Decreased: Hemoglobin, hematocrit, platelets, albumin, total protein
  • Altered: Glucose tolerance

Geriatric Considerations

Elderly patients may have different reference ranges for:

  • Creatinine clearance (decreases with age)
  • Alkaline phosphatase (may be elevated)
  • TSH (may trend higher)
  • Glucose (fasting levels may be slightly higher)

Critical Values Requiring Immediate Notification

TestCritical LowCritical High
Sodium<120 mEq/L>160 mEq/L
Potassium<2.5 mEq/L>6.5 mEq/L
Glucose<40 mg/dL>500 mg/dL
Calcium (ionized)<3.5 mg/dL>7.0 mg/dL
Calcium (total)<6.5 mg/dL>13.0 mg/dL
Hemoglobin<7.0 g/dL>20.0 g/dL
White Blood Cell Count<1.5 × 10^3/μL>30.0 × 10^3/μL
Platelet Count<20 × 10^3/μL>1000 × 10^3/μL
pH<7.20>7.60
PO2<40 mmHg>70 mmHg for patients on oxygen
PCO2<20 mmHg>70 mmHg
Troponin IN/A>0.5 ng/mL
INRN/A>5.0
Drug LevelsBelow therapeuticAbove therapeutic

Best Practices for Laboratory Result Interpretation

General Principles

  1. Compare to reference ranges: Note that ranges may vary slightly between laboratories
  2. Consider patient factors: Age, sex, pregnancy status, medications, and timing can all affect results
  3. Examine trends: Serial measurements often provide more information than single values
  4. Assess clinical context: Lab results must be interpreted in the context of the patient’s symptoms and condition
  5. Confirm unusual results: Consider repeating critically abnormal or unexpected results

Common Interpretation Pitfalls

  1. Ignoring preanalytical factors: Fasting status, timing, medication effects, sample handling
  2. Over-relying on “normal” ranges: Up to 5% of healthy individuals may fall outside reference ranges
  3. Failing to consider interfering substances: Hemolysis, lipemia, certain medications
  4. Missing critical values: Some abnormal results require immediate action
  5. Interpreting results in isolation: Consider related tests and clinical findings

Resources for Further Learning

Official Guidelines and References

  • Clinical Laboratory Standards Institute (CLSI): www.clsi.org
  • American Association for Clinical Chemistry (AACC): www.aacc.org
  • College of American Pathologists (CAP): www.cap.org
  • Laboratory Test Interpretation: Evidence-Based Approach

Mobile Applications

  • Medscape: Laboratory Medicine reference
  • Lab Values Medical Reference
  • Davis’s Laboratory and Diagnostic Tests

When to Consult a Specialist

  • For complex or ambiguous results
  • When results don’t match clinical presentation
  • For rare or specialized tests
  • When diagnostic algorithms indicate advanced testing

Remember: Laboratory tests are tools to aid in clinical decision-making and should never replace clinical judgment. Always consider the patient’s complete clinical picture when interpreting laboratory results.

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