Published: 27 Oct 2024

Normal Reference Ranges for Common Lab Tests in Adults

Establishing normal reference ranges for laboratory tests allows clinicians to assess whether a patient's results fall within expected limits. These ranges vary based on factors such as age, gender, and laboratory techniques used.

Blood Count Tests

* White Blood Cell (WBC) Count: 4,500-11,000 cells/µL
* Red Blood Cell (RBC) Count:
* Men: 4.7-6.1 million cells/µL
* Women: 4.2-5.4 million cells/µL
* Hemoglobin (Hb):
* Men: 13.8-17.2 g/dL
* Women: 12.1-15.1 g/dL
* Hematocrit (Hct):
* Men: 41-50%
* Women: 36-44%
* Platelet Count: 150,000-450,000/µL

Electrolytes and Minerals

* Sodium (Na): 135-145 mEq/L
* Potassium (K): 3.5-5.0 mEq/L
* Chloride (Cl): 96-106 mEq/L
* Calcium (Ca): 8.5-10.5 mg/dL
* Magnesium (Mg): 1.7-2.2 mg/dL
* Phosphate: 2.5-4.5 mg/dL

Renal Function Tests

* Blood Urea Nitrogen (BUN): 7-20 mg/dL
* Creatinine:
* Men: 0.6-1.2 mg/dL
* Women: 0.5-1.1 mg/dL
* Glomerular Filtration Rate (GFR): 90-120 mL/min (age-dependent)

Liver Function Tests

* Alanine Aminotransferase (ALT): 7-56 U/L
* Aspartate Aminotransferase (AST): 10-40 U/L
* Alkaline Phosphatase (ALP): 44-147 U/L
* Bilirubin: 0.1-1.2 mg/dL
* Albumin: 3.5-5.0 g/dL

Thyroid Function Tests

* Thyroid Stimulating Hormone (TSH): 0.4-4.0 mIU/L
* Free T4 (Thyroxine): 0.8-1.8 ng/dL
* Free T3 (Triiodothyronine): 2.3-4.1 pg/mL

Lipid Panel

* Total Cholesterol: Below 200 mg/dL
* LDL Cholesterol: Below 100 mg/dL (optimal)
* HDL Cholesterol:
* Men: Above 40 mg/dL
* Women: Above 50 mg/dL
* Triglycerides: Below 150 mg/dL

Glucose and Diabetes Markers

* Fasting Blood Glucose: 70-99 mg/dL (fasting)
* Hemoglobin A1c (HbA1c): Below 5.7% (for non-diabetics)

Inflammation Markers

* C-Reactive Protein (CRP): Below 3.0 mg/L
* Erythrocyte Sedimentation Rate (ESR):
* Men: 0-15 mm/hr
* Women: 0-20 mm/hr

Tips for Specifying and Interpreting Ranges:

* Laboratory Reference Variability: Consult the specific lab's reference ranges as they may vary slightly.
* Patient Factors: Consider factors like age, gender, ethnicity, medications, and pre-existing conditions.
* Adjusting Ranges for Comorbidities: Patients with chronic conditions may have adjusted ranges, particularly for renal, liver, and glucose tests.
* Clinical Context: Results outside the "normal" range may still be acceptable for some patients based on symptoms and medical history.