Lab values, in the units Canadian charts actually use
Haemoglobin reads 128 g/L here and 12.8 g/dL in American question banks. Glucose reads 5.4 mmol/L, not 98 mg/dL. Creatinine is in micromoles. Studying in the wrong units builds the wrong reflexes, and reflexes are what you have left at hour four of an adaptive exam. Both systems are below, with the conversion factor between them.
Electrolytes
Sodium, potassium, chloride, calcium, magnesium and phosphate.
| Analyte | SI range | Conventional | × to SI | Critical |
|---|---|---|---|---|
| SodiumNa⁺ Hyponatraemia presents neurologically before it presents chemically. Confusion and headache come first; correct slowly to avoid osmotic demyelination. | 135–145 mmol/L | 135–145 mEq/L | 1 | < 120 mmol/L — seizure risk > 160 mmol/L |
| PotassiumK⁺ Never give IV potassium by push. Ever. It is the single most reliably tested medication-safety fact on the exam. | 3.5–5 mmol/L | 3.5–5 mEq/L | 1 | < 2.5 mmol/L > 6.5 mmol/L — peaked T waves, arrest risk |
| ChlorideCl⁻ Moves with sodium; useful for identifying the type of acid-base disturbance. | 98–107 mmol/L | 98–107 mEq/L | 1 | — |
| Calcium (total)Ca²⁺ Low calcium means Chvostek and Trousseau signs, and airway risk from laryngospasm. Keep calcium gluconate available. | 2.12–2.62 mmol/L | 8.5–10.5 mg/dL | 0.25 | < 1.65 mmol/L — tetany > 3.25 mmol/L |
| MagnesiumMg²⁺ During magnesium sulphate infusion, absent patellar reflex is the first sign of toxicity. Calcium gluconate is the antidote. | 0.7–1 mmol/L | 1.6–2.6 mg/dL | 0.411 | > 2.5 mmol/L — loss of deep tendon reflexes |
| Phosphate Moves inversely to calcium. Rises in renal failure. | 0.8–1.45 mmol/L | 2.5–4.5 mg/dL | 0.323 | — |
Renal function
Urea, creatinine and eGFR.
| Analyte | SI range | Conventional | × to SI | Critical |
|---|---|---|---|---|
| UreaBUN Rises with dehydration and GI bleeding as well as with renal impairment. | 2.5–7.1 mmol/L | 7–20 mg/dL | 0.357 | — |
| Creatinine The more specific renal marker. Check before contrast studies, metformin and nephrotoxic antibiotics. | 53–106 µmol/L | 0.6–1.2 mg/dL | 88.4 | > 350 µmol/L |
| eGFR Below 30 changes drug dosing across the board. Below 15 is end-stage. | 90–120 mL/min/1.73m² | — | — | — |
Haematology
Complete blood count and differential.
| Analyte | SI range | Conventional | × to SI | Critical |
|---|---|---|---|---|
| Haemoglobin (female)Hgb Note the SI unit: Canadian charts read 128 g/L, not 12.8 g/dL. Candidates trained on US banks routinely misread this by a factor of ten. | 120–160 g/L | 12–16 g/dL | 10 | < 70 g/L — transfusion threshold in most protocols |
| Haemoglobin (male)Hgb Assess for fatigue, tachycardia and pallor before the number alarms you. | 140–180 g/L | 14–18 g/dL | 10 | < 70 g/L |
| HaematocritHct Roughly three times the haemoglobin. Useful as a sanity check on a reported value. | 0.37–0.47 L/L | 37–47 % | 0.01 | — |
| White blood cellsWBC A neutropenic client with a fever is an emergency, even when they look well. Immunosuppression blunts every other sign. | 4–11 ×10⁹/L | 4000–11000 /mm³ | 0.001 | < 1.0 ×10⁹/L — neutropenic precautions |
| PlateletsPlt Below 50, hold invasive procedures and switch to a soft toothbrush and electric razor. | 150–400 ×10⁹/L | — | — | < 50 ×10⁹/L — bleeding precautions; < 20 spontaneous bleeding |
Coagulation
INR, PT, aPTT and platelets in the context of anticoagulation.
| Analyte | SI range | Conventional | × to SI | Critical |
|---|---|---|---|---|
| INR Therapeutic range on warfarin is 2.0 to 3.0 for most indications. Vitamin K is the reversal agent. | 0.8–1.2 ratio | — | — | > 5.0 — major bleeding risk |
| aPTT Monitors unfractionated heparin; therapeutic is 1.5 to 2.5 times control. Protamine sulphate reverses it. | 25–35 seconds | — | — | — |
Liver function
ALT, AST, ALP, bilirubin and albumin.
| Analyte | SI range | Conventional | × to SI | Critical |
|---|---|---|---|---|
| ALT The most liver-specific transaminase. Watch it on statins and acetaminophen. | 7–56 U/L | — | — | — |
| Total bilirubin Jaundice becomes visible above roughly 40 µmol/L, first in the sclera. | 3–20 µmol/L | 0.2–1.2 mg/dL | 17.1 | — |
| Albumin Low albumin means oedema and altered protein binding, so free drug levels rise. | 35–50 g/L | 3.5–5 g/dL | 10 | — |
Cardiac markers
Troponin, BNP and CK.
| Analyte | SI range | Conventional | × to SI | Critical |
|---|---|---|---|---|
| Troponin I (high sensitivity) The trend matters more than the single value — this is exactly what NGN trend items are built to test. | 0–14 ng/L | — | — | Rising serial values indicate myocardial injury |
| BNP Rises with fluid overload. Correlate with weight gain, crackles and orthopnoea. | 0–100 ng/L | — | — | > 400 ng/L suggests heart failure |
Arterial blood gases
pH, PaCO₂, HCO₃⁻ and PaO₂.
| Analyte | SI range | Conventional | × to SI | Critical |
|---|---|---|---|---|
| pH Read pH first, then PaCO₂, then HCO₃⁻. The one that matches the pH direction is the cause. | 7.35–7.45 | — | — | < 7.20 > 7.60 |
| PaCO₂ Respiratory component. Rises when ventilation fails. | 35–45 mmHg | — | — | — |
| BicarbonateHCO₃⁻ Metabolic component. Falls in diabetic ketoacidosis and in prolonged diarrhoea. | 22–26 mmol/L | — | — | — |
| PaO₂ Below 60 the oxyhaemoglobin curve falls off a cliff. Small drops become large desaturations. | 80–100 mmHg | — | — | < 60 mmHg — corresponds to roughly 90% saturation |
Endocrine
Glucose, HbA1c and thyroid studies.
| Analyte | SI range | Conventional | × to SI | Critical |
|---|---|---|---|---|
| Glucose (fasting) The rule of 15: 15 g of carbohydrate, recheck in 15 minutes. Canadian charts read 5.4 mmol/L, not 98 mg/dL. | 4–6 mmol/L | 70–110 mg/dL | 0.0555 | < 3.0 mmol/L — treat with 15 g fast-acting carbohydrate > 25 mmol/L — assess for DKA or HHS |
| HbA1c Reflects roughly three months of control. Target is usually 7.0% or below. | 4–6 % | — | — | — |
| TSH High TSH means hypothyroid. Levothyroxine is taken on an empty stomach, separate from calcium and iron. | 0.4–4 mIU/L | — | — | — |
Therapeutic drug levels
Narrow-therapeutic-index drugs the exam tests relentlessly.
| Analyte | SI range | Conventional | × to SI | Critical |
|---|---|---|---|---|
| Digoxin Hypokalaemia potentiates digoxin toxicity. Hold and report an apical rate below 60 in an adult. | 0.6–2.6 nmol/L | 0.5–2 ng/mL | 1.281 | Toxicity: nausea, visual halos, bradycardia |
| Lithium Dehydration and sodium loss raise lithium levels. Maintain steady fluid and salt intake; avoid NSAIDs. | 0.6–1.2 mmol/L | — | — | > 1.5 mmol/L — toxicity |
| Vancomycin (trough) Draw the trough within 30 minutes before the next dose. Monitor creatinine for nephrotoxicity. | 10–20 mg/L | — | — | — |
Reference ranges vary slightly between laboratories and between institutions. These are the ranges used across Canadian nursing curricula and licensure examinations. On the floor, always use the range printed on the result your own lab issued.