liminfoLab Values Reference
Free reference guide: Lab Values Reference
About Lab Values Reference
The Lab Values Reference is a searchable clinical laboratory cheat sheet covering normal ranges, critical values, and diagnostic interpretation patterns for healthcare professionals. The hematology section includes CBC with gender-specific ranges (WBC 4,500-11,000/uL, Hb male 13.5-17.5/female 12.0-16.0 g/dL, platelets 150,000-400,000/uL), WBC differential counts with left shift criteria, coagulation studies (PT, INR therapeutic targets for AF/DVT and mechanical valves, aPTT heparin monitoring), iron studies with differential diagnosis patterns for iron deficiency vs. chronic disease vs. hemochromatosis, and hemoglobin electrophoresis for sickle cell and thalassemia evaluation.
The chemistry section covers BMP (sodium, potassium with critical levels, anion gap calculation), CMP with liver enzymes (AST/ALT patterns for hepatocellular vs. cholestatic injury, AST/ALT ratio >2 suggesting alcoholic liver disease), lipid panel with NCEP ATP III classifications, cardiac markers (troponin I/T kinetics, BNP/NT-proBNP age-adjusted cutoffs for heart failure), ABG interpretation with acid-base disorders and A-a gradient, renal function (eGFR, BUN/Cr ratio differential, FENa for prerenal vs. intrinsic), pancreatic enzymes, electrolyte critical values, and vitamin/mineral reference ranges.
Endocrine and immunology sections include thyroid panel with hyper/hypothyroid interpretation, HbA1c diagnostic criteria and treatment targets by patient population, diabetes diagnosis (fasting glucose, OGTT, gestational diabetes criteria), pregnancy labs with beta-hCG doubling times, tumor markers (PSA, CEA, AFP, CA-125, CA 19-9) for monitoring rather than screening, autoimmune panel (ANA titers, anti-dsDNA, anti-CCP, ANCA patterns for vasculitis), hepatitis serology (HBV/HCV marker interpretation for acute, chronic, recovered, and vaccinated status), urinalysis, and CSF analysis with bacterial vs. viral vs. tuberculous meningitis patterns.
Key Features
- Complete CBC with gender-specific ranges, RBC indices (MCV, MCH, MCHC, RDW), WBC differential, and platelet parameters
- Metabolic panels (BMP/CMP) with anion gap calculation, liver enzyme patterns, lipid classifications, and critical electrolyte levels
- Cardiac marker kinetics: troponin I/T onset and peak times, BNP/NT-proBNP age-stratified heart failure cutoffs
- ABG interpretation framework with acid-base disorders, compensation rules, and A-a gradient normal values
- Coagulation cascade: PT/INR therapeutic ranges for anticoagulation, aPTT monitoring, DIC diagnostic criteria
- Endocrine panels: thyroid function (TSH, Free T4/T3), HbA1c targets by population, and diabetes diagnostic criteria
- Autoimmune serology: ANA titer interpretation, disease-specific antibodies (anti-dsDNA, anti-CCP, ANCA), and hepatitis panel
- Body fluid analysis: urinalysis with proteinuria ratios, and CSF patterns for bacterial, viral, and tuberculous meningitis
Frequently Asked Questions
What lab values are included in this reference?
This reference covers over 20 major laboratory test panels including CBC with differential, BMP, CMP, liver panel, lipid panel, thyroid panel, cardiac markers, coagulation studies, iron studies, ABG, HbA1c, renal function, inflammatory markers, electrolytes, pancreatic enzymes, urinalysis, CSF analysis, tumor markers, pregnancy labs, hemoglobin electrophoresis, autoimmune panel, hepatitis serology, and vitamin/mineral levels. Each entry includes normal ranges, critical values, and clinical interpretation patterns.
How do I interpret the CBC results?
Key CBC values: WBC 4,500-11,000/uL (elevated in infection, low in bone marrow suppression), Hemoglobin male 13.5-17.5 g/dL and female 12.0-16.0 g/dL (low = anemia), MCV 80-100 fL (low = microcytic like iron deficiency, high = macrocytic like B12/folate deficiency), Platelets 150,000-400,000/uL. The WBC differential shows neutrophil (40-70%), lymphocyte (20-40%), monocyte (2-8%), eosinophil (1-4%), and basophil (0-1%) percentages. Left shift (bands >6%) suggests acute bacterial infection.
What is the anion gap and how do I calculate it?
Anion gap = Na - (Cl + HCO3), with a normal range of 8-12 mEq/L. An elevated anion gap indicates metabolic acidosis caused by unmeasured anions. The MUDPILES mnemonic covers common causes: Methanol, Uremia, Diabetic ketoacidosis, Propylene glycol, Isoniazid/Iron, Lactic acidosis, Ethylene glycol, and Salicylates. A normal anion gap metabolic acidosis (hyperchloremic) suggests renal tubular acidosis or GI bicarbonate loss.
How do I differentiate types of liver injury using lab patterns?
Hepatocellular injury shows AST/ALT significantly elevated relative to ALP (AST/ALT >> ALP). Cholestatic injury shows ALP/GGT elevated relative to AST/ALT. An AST/ALT ratio >2 suggests alcoholic liver disease. Acute hepatitis typically shows ALT >1,000 U/L. For liver synthetic function, check albumin (3.5-5.0 g/dL) and PT/INR. Direct bilirubin elevation indicates conjugated hyperbilirubinemia (obstruction), while indirect elevation suggests hemolysis or Gilbert syndrome.
How do I interpret thyroid function tests?
Normal ranges: TSH 0.4-4.0 mIU/L, Free T4 0.8-1.8 ng/dL, Free T3 2.3-4.2 pg/mL. Hyperthyroidism shows low TSH with elevated Free T4/T3 (Graves disease, toxic nodule). Hypothyroidism shows elevated TSH with low Free T4 (Hashimoto thyroiditis, post-ablation). Subclinical disease shows abnormal TSH with normal Free T4. In early subacute thyroiditis, TSH is low with transiently elevated thyroid hormones. Anti-TPO antibodies suggest autoimmune thyroiditis.
What are the diagnostic criteria for diabetes using lab values?
Diabetes is diagnosed by any one of: fasting glucose >= 126 mg/dL, 2-hour OGTT >= 200 mg/dL, HbA1c >= 6.5%, or random glucose >= 200 mg/dL with classic symptoms. Prediabetes: fasting 100-125 mg/dL (IFG), 2-hour 140-199 mg/dL (IGT), or HbA1c 5.7-6.4%. Treatment targets: HbA1c <7% for most adults, <6.5% for younger patients without complications, <8% for elderly or high hypoglycemia risk. Estimated average glucose (eAG) = 28.7 x A1c - 46.7 mg/dL.
How do I use cardiac markers to diagnose myocardial infarction?
Troponin I (<0.04 ng/mL) or high-sensitivity Troponin T (<14 ng/L) is the primary biomarker. Troponin rises 3-6 hours after onset and peaks at 12-24 hours. A rise and/or fall pattern with at least one value above the 99th percentile is diagnostic. CK-MB (<5 ng/mL) is less specific. BNP (<100 pg/mL) and NT-proBNP (<300 pg/mL) are used to rule out heart failure rather than MI. NT-proBNP has age-adjusted cutoffs: <450 for age <50, <900 for 50-75, <1800 for >75 years.
How do I interpret CSF analysis for meningitis?
Normal CSF: clear, 0-5 WBC/uL (lymphocyte predominant), protein 15-45 mg/dL, glucose 40-70 mg/dL (60% of serum). Bacterial meningitis: WBC 1,000-5,000 with PMN predominance, elevated protein, low glucose (<40 mg/dL). Viral meningitis: WBC 10-500 with lymphocyte predominance, mildly elevated protein, normal glucose. Tuberculous meningitis: lymphocyte predominance, high protein, low glucose. Opening pressure is elevated (>20 cmH2O) in bacterial and fungal meningitis.