Patient History & Laboratory Values

4,000 – 11,000

Mnemonic: "4 to 11" — like the hours of a normal workday

Over 16,000 → patient needs antibiotics.

4 – 6 million/mm³

Mnemonic: WBC is 4–11 (thousand), RBC is 4–6 (million) — same "4" start, RBC is smaller/higher-order.

13.5 – 15.5 g/dL

Mnemonic: Men are "+1" over women: 13.5–15.5 vs 12.5–14.5.

1.34 mL O₂ per gram of Hgb.

12.5 – 14.5 g/dL

Mnemonic: Women 12.5–14.5; Men +1 → 13.5–15.5.

42 – 52%

Mnemonic: Hct ≈ 3× Hgb. Male Hgb 14 → Hct ~42.

Hct reflects hydration status.

37 – 48%

Mnemonic: Female Hgb 13 → Hct ~37. "Rule of 3."

150,000 – 400,000

Mnemonic: "150 low bleeds, 400 high clots." <150k thrombocytopenia, >400k thrombocytosis.

~60% of WBC

Mnemonic: Mature cells. DOWN with bacterial infection (the mature ones get consumed).

~4% of WBC

Mnemonic: Immature cells. UP with bacterial infection (bone marrow ships them out early).

25 – 35%

Mnemonic: Second-largest WBC slice (after segmented neutrophils ~60%).

4 – 6%

Mnemonic: "Mono → TB." Elevation associated with tuberculosis.

~2%

Mnemonic: "E for Eosinophils = E for Ease of breathing compromised." Allergy / asthma.

0.4 – 1%

Mnemonic: The smallest slice — less than 1% of the whole pie.

135 – 145 mmol/L

Mnemonic: "135–145" — count by 5s from 130. Primary EXTRAcellular cation.

Salt lives outside the cell.

3.5 – 5.0 mmol/L

Mnemonic: "Banana is 3.5–5." Primary INTRAcellular cation — heart & kidney function.

Hyperkalemia ↔ metabolic ACIDosis. Hypokalemia ↔ metabolic ALKalosis.

98 – 106 mEq/L

Mnemonic: "Close to 100." Primary EXTRAcellular anion — rides along with sodium.

22 – 29 mEq/L

Mnemonic: "Bicarb-ish" range in the 20s.

↑ TCO₂ = ventilatory failure. ↓ TCO₂ = metabolic acidosis / hyperventilation / diarrhea.

70 – 105 mg/dL

Mnemonic: "70s to 100s." Below 70 = hypoglycemia, above 105 fasting = hyperglycemia.

7 – 20 mg/dL

Mnemonic: "7 days a week, 20 bucks for BUN."

↑ BUN = kidney. ↓ BUN = liver or malnutrition.

0.7 – 1.3 mg/dL

Mnemonic: BUN starts at 7, Creatinine starts at 0.7 — "shift the decimal."

↑ = kidney. ↓ = liver. Pair with BUN for renal function.

12 – 15 seconds

Mnemonic: "PT pairs with Warfarin" — both start with hard consonants: P-W.

Warfarin = Coumadin.

0.8 – 1.1

Mnemonic: Think "1.0 ± a hair." High = bleeds, Low = clots fast.

23 – 32 seconds

Mnemonic: "A-P-T-T / Hep." Both contain a "T" — tie them together.

Roughly double the PT range (12–15 → 23–32).