Lab Ranges

Good luck, nursing students.

Sodium (Na⁺)

135–145 mEq/L — Maintains fluid balance; supports nerve & muscle function

Potassium (K⁺)

3.5–5.0 mEq/L — Vital for cardiac rhythm and muscle contraction

Chloride (Cl⁻)

95–105 mEq/L — Helps maintain acid-base and fluid balance

Bicarbonate (HCO₃⁻)

22–26 mEq/L — Key buffer in acid-base balance

Blood Urea Nitrogen (BUN)

7–20 mg/dL — Indicates kidney function

Creatinine

0.6–1.2 mg/dL — Reflects kidney function and filtration

Glucose (fasting)

70–110 mg/dL — Main source of body’s energy; elevated in diabetes

Calcium (Ca²⁺)

9–10.5 mg/dL — Important for bone health, nerve impulses, muscle contraction

White Blood Cells (WBC)

4,000–11,000 /µL — Elevated in infection or inflammation

Red Blood Cells (RBC)

M: 4.7–6.1 / F: 4.2–5.4 million/µL — Carry oxygen throughout the body

Hemoglobin (Hgb)

M: 14–18 / F: 12–16 g/dL — Measures oxygen-carrying capacity; low in anemia

Hematocrit (Hct)

M: 42–52% / F: 37–47% — Percentage of red blood cells in total blood volume

Platelets

150,000–400,000 /µL — Help with clot formation; low levels increase bleeding risk

Prothrombin Time (PT)

11–13 seconds — Evaluates extrinsic clotting pathway (warfarin)

INR

0.8–1.2 (therapeutic 2–3) — Standardized clotting time for patients on anticoagulants

aPTT

25–35 seconds — Tests intrinsic clotting pathway (heparin therapy)

pH

7.35–7.45 — Indicates acid-base balance

PaCO₂

35–45 mmHg — Reflects respiratory component (CO₂ retention or loss)

HCO₃⁻

22–26 mEq/L — Reflects metabolic component

PaO₂

80–100 mmHg — Measures oxygen in arterial blood

SaO₂

95–100% — Measures oxygen saturation of hemoglobin

ALT

10–40 U/L — Liver enzyme; high levels mean liver injury

AST

10–40 U/L — Enzyme found in liver and muscle; high in liver or muscle damage

Alkaline Phosphatase (ALP)

40–120 U/L — Indicates bile duct, bone, or liver disease

Total Bilirubin

0.2–1.2 mg/dL — Elevated in liver dysfunction or bile obstruction

Albumin

3.5–5.0 g/dL — Maintains oncotic pressure; reflects liver or nutritional status

Total Protein

6.0–8.3 g/dL — Indicates overall nutritional and liver status

Troponin I

<0.03 ng/mL — Sensitive marker for cardiac muscle injury

CK-MB

0–5 ng/mL — Cardiac enzyme; elevated after heart attack

BNP

<100 pg/mL — Indicates heart failure if elevated

Magnesium (Mg²⁺)`

1.8–2.6 mEq/L — Needed for neuromuscular and cardiac function

Phosphate (PO₄³⁻)

3.0–4.5 mg/dL — Involved in bone metabolism and energy production

Ammonia

10–80 mcg/dL — Elevated in liver failure or hepatic encephalopathy

Lactic Acid

0.5–2.2 mmol/L — Elevated in tissue hypoxia or sepsis

Lipase

10–140 U/L — Elevated in pancreatitis

Amylase

25–125 U/L — Elevated in pancreatitis

Hyponatremia

(<135 mEq/L) Headache, confusion, seizures, nausea, muscle cramps

Hypernatremia

(>145 mEq/L) Thirst, dry mucosa, agitation, seizures, cellular dehydration

Hypokalemia

(<3.5 mEq/L) Weakness, flattened T wave, U wave, constipation, arrhythmia risk

Hyperkalemia

(>5.0 mEq/L) Tall peaked T waves, weakness, paresthesia, risk of asystole

Hypocalcemia

(<9 mg/dL) Twitching, tingling, Chvostek's, Trousseau's, prolonged QT

Hypercalcemia

(>10.5 mg/dL) Bone pain, kidney stones, constipation, reduced reflexes, shortened QT

Hypomagnesemia

(<1.8 mEq/L) Tremors, hyperreflexia, Torsades risk, cramps, insomnia

Hypermagnesemia

(>2.6 mEq/L) Decreased reflexes, hypotension, respiratory depression, cardiac arrest risk

Hypochloremia

(<98 mEq/L) Metabolic alkalosis signs, shallow breathing, irritability

Hyperchloremia

(>106 mEq/L) Metabolic acidosis signs, deep rapid breathing, fatigue

Low Hemoglobin

Anemia, fatigue, pallor, shortness of breath

High Hemoglobin

Dehydration, polycythemia, thick blood

Low Hematocrit

Fluid overload, blood loss

High Hematocrit

Dehydration, chronic hypoxia

Leukopenia

(WBC <4.0) Infection risk, immunocompromised

Leukocytosis

(WBC >11.0) Infection, inflammation, stress

Thrombocytopenia

(Plt <150) Bleeding risk, bruising, petechiae

Thrombocytosis

(Plt >400) Clotting risk, thrombosis

Low BUN

(<7 mg/dL) Liver dysfunction, overhydration

High BUN

(>20 mg/dL) Dehydration, kidney dysfunction

Low Creatinine

(<0.6 mg/dL) Low muscle mass

High Creatinine

(>1.2 mg/dL) Impaired kidney function

Hypoglycemia

(<70 mg/dL) Sweating, shaking, confusion

Hyperglycemia

(>110 mg/dL fasting) Polyuria, polydipsia, fatigue

Low INR

Blood clots too easily

High INR

Increased bleeding risk

Acidosis

(pH <7.35) Confusion, fatigue, hyperkalemia

Alkalosis

(pH >7.45) Tingling, spasms, arrhythmias