Lab Values & ABG Interpretation: Mnemonics and Clinical Significance

Sodium (Na)

Normal range is 135-145 MEQ/L. Remember odd numbers: 1, 3, 5 = 135.

Potassium (K)

Normal range is 3.5-5 MEQ/L. Think of 3-5 bananas per bunch, and remember the 'half off' to recall the 1/2.

BUN (Blood Urea Nitrogen)

Normal range is 5-20 MG/DL. Use the mnemonic 'BUNion': 5 digits per limb, 20 digits total.

Creatinine

Normal range is 0.6-1.2 MG/DL. 0.9 is the midpoint, with 0.6 and 1.2 as the limits.

Magnesium (Mg)

Normal range is 1.5-2.5 MG/DL. Think of a magnifying glass that magnifies 1.5-2.5X.

Calcium (Ca)

Normal range is 9-11 MG/DL. Remember to 'Call 9-11' for emergencies.

Hemoglobin (HGB)

Male 13-18 G/DL, Female 12-16 G/DL. Think of puberty ages: males grow from 13-18, females from 12-16.

Hematocrit (HCT)

Male 39-54%, Female 36-48%. Remember to multiply HGB by 3 to get HCT values.

White Blood Cells (WBC)

Normal range is 4000-11000 U/DL. Remember 'Kids ages 4-11 always get sick'.

Platelets (PLT)

Normal range is 150,000-450,000 /UL. Think of China plates costing $150-$400.

Prothrombin Time (PT)

Normal range is 10-13 seconds. Remember 'Pre-Teen is 10-13 years old'.

Partial Thromboplastin Time (PTT)

Normal range is 25-35 seconds. Think of the age of most professional athletes.

Chloride (Cl)

Normal range is 95-105 MEQ/L. Best time to go in the pool is when it's 95-105 degrees outside.

Glucose

Normal range is 70-100 MG/DL. Energy is low at 70-100 years old.

Phosphorus (P)

Normal range is 2.5-4.5 MG/DL. 'FOR US' where 'PHOR=4' and 'US=2 letters'.

Arterial Blood Gas (ABG)

Measures acid-base balance, with normal pH range of 7.35-7.45.

CO2

Normal range is 35-45 MMHG. Remember to drop the 7 from pH to get CO2 range.

HCO3

Normal range is 22-26 MEQ/L, representing bicarbonate levels.

pH

Indicates acid-base balance; normal range is 7.35-7.45. Values below 7.35 indicate acidosis, above 7.45 indicate alkalosis.

PaO2

Normal range is 80-100 MMHG, measures oxygenation status but not used to determine ABG.

Compensation

If pH is normal, determine if it's closer to acidosis or alkalosis. If pH is out of range and CO2 or HCO3 is in range, it's uncompensated.

Tic-Tac-Toe Method

Use this method to determine if the condition is respiratory or metabolic. If pH and CO2 are in the same column, it's respiratory; if pH and HCO3 are in the same column, it's metabolic.

Compensated vs. Uncompensated

If all three values are out of range, it's partially compensated. If pH is normal, it's fully compensated.

Hyperkalemia

Levels > 5 MEQ/L. Symptoms include peaked T waves on EKG. Causes include burns, Addison's disease, excessive intake, and decreased excretion due to kidney disease.

Treatment for Hyperkalemia

Monitor EKG, stop potassium solutions, restrict dietary potassium, and use potassium-wasting diuretics if necessary. Emergency treatment includes calcium gluconate and insulin with glucose.

Hypokalemia

Levels < 3.5 MEQ/L. Symptoms include muscle cramps, weakness, and EKG changes like T wave inversion. Causes include poor intake, excessive loss, and dilution of serum potassium.

Treatment for Hypokalemia

Potassium supplementation (oral or IV), monitoring EKG changes, and ensuring magnesium and calcium levels are stable.

Signs and Symptoms of Hypokalemia

Remember the 6 L's for hypokalemia: lethargy, leg cramps, limp muscles, low respirations, lethal dysrhythmias, and lots of urine.