The "Nurse Head" Cheat Sheet: Labs vs. Patient Symptoms
Normal Critical Low (The Critical High (The
Lab Test Range Danger) Danger) Nurse Head Tip
Potassium 3.5 – 5.0 < 3.5 (Hypokalemia)Symp: > 5.0 K+ is Priority #1. If K+ is
(K+) mEq/L Muscle cramps, (Hyperkalemia)Symp: high or low, put them on
arrhythmias (U-waves). Peaked T-waves, cardiac a Heart Monitor
arrest. immediately. Never
push K+ IV push!
Sodium 135 – < 135 > 145 Sodium = Neuro. If the
(Na+) 145 (Hyponatremia)Symp: (Hypernatremia)Symp: Sodium is messed up,
mEq/L Confusion, seizures, Thirst, dry tongue, check the patient's Level
coma. swollen/red skin. of Consciousness
(LOC).
Hemoglobin 12 – 18 < 7.0Symp: Pale skin, > 18Symp: Clotting risk, If Hgb is < 7, prepare for
(Hgb) g/dL shortness of breath, stroke risk. a blood transfusion. If
tachycardia. it's 8-10, just monitor
and conserve energy.
Normal
Lab Test Range Critical Low / High Nurse Head Tip
Magnesium 1.5 – 2.5 Low: Torsades de Pointes (Wild Mg is the "Sheriff." If Mg is low, the
(Mg) mEq/L EKG)High: Loss of Deep Tendon heart goes wild. If Mg is high, the body
Reflexes goes limp (respiratory arrest).
Calcium (Ca) 8.5 – 10.5 Low: Tetany (Chvostek's/Trousseau's Remember: Calcium acts like a
mg/dL sign)High: Muscle weakness, stones sedative. Low Ca = Excited muscles
(spasms). High Ca = Lazy muscles.
Phosphorus 2.5 – 4.5 Inverse to Calcium If Calcium is high, Phosphorus is low.
mg/dL Monitor Ca/Phos balance in kidney
patients.
Chloride (Cl) 98 – 106 Follows Sodium Usually mirrors Sodium levels.
mEq/L Essential for acid-base balance.
BUN 10 – 20 High: Dehydration or Kidney damage If BUN is high but Creatinine is normal
mg/dL = Dehydration. If BOTH are high =
Kidney Failure.
Creatinine 0.6 – 1.2 High: Kidney Failure The Best indicator of kidney function. If
mg/dL this is elevated, assume renal
impairment.
WBC 5,000 – Low: Neutropenia (Risk of If < 1,000, place on "Neutropenic
10,000 infection)High: Infection Precautions" (No fresh flowers, no raw
fruit, dedicated equipment).
Platelets 150k – Low (<100k): Bleeding riskCritical If low, NO unnecessary needles, NO
400k (<50k): Hemorrhage risk aspirin, soft toothbrush only.
PT 11 – 12.5 Measures clotting (extrinsic) Used to monitor Warfarin (Coumadin)
sec therapy in conjunction with INR.
Normal Critical Low (The Critical High (The
Lab Test Range Danger) Danger) Nurse Head Tip
Potassium 3.5 – 5.0 < 3.5 (Hypokalemia)Symp: > 5.0 K+ is Priority #1. If K+ is
(K+) mEq/L Muscle cramps, (Hyperkalemia)Symp: high or low, put them on
arrhythmias (U-waves). Peaked T-waves, cardiac a Heart Monitor
arrest. immediately. Never
push K+ IV push!
Sodium 135 – < 135 > 145 Sodium = Neuro. If the
(Na+) 145 (Hyponatremia)Symp: (Hypernatremia)Symp: Sodium is messed up,
mEq/L Confusion, seizures, Thirst, dry tongue, check the patient's Level
coma. swollen/red skin. of Consciousness
(LOC).
Hemoglobin 12 – 18 < 7.0Symp: Pale skin, > 18Symp: Clotting risk, If Hgb is < 7, prepare for
(Hgb) g/dL shortness of breath, stroke risk. a blood transfusion. If
tachycardia. it's 8-10, just monitor
and conserve energy.
Normal
Lab Test Range Critical Low / High Nurse Head Tip
Magnesium 1.5 – 2.5 Low: Torsades de Pointes (Wild Mg is the "Sheriff." If Mg is low, the
(Mg) mEq/L EKG)High: Loss of Deep Tendon heart goes wild. If Mg is high, the body
Reflexes goes limp (respiratory arrest).
Calcium (Ca) 8.5 – 10.5 Low: Tetany (Chvostek's/Trousseau's Remember: Calcium acts like a
mg/dL sign)High: Muscle weakness, stones sedative. Low Ca = Excited muscles
(spasms). High Ca = Lazy muscles.
Phosphorus 2.5 – 4.5 Inverse to Calcium If Calcium is high, Phosphorus is low.
mg/dL Monitor Ca/Phos balance in kidney
patients.
Chloride (Cl) 98 – 106 Follows Sodium Usually mirrors Sodium levels.
mEq/L Essential for acid-base balance.
BUN 10 – 20 High: Dehydration or Kidney damage If BUN is high but Creatinine is normal
mg/dL = Dehydration. If BOTH are high =
Kidney Failure.
Creatinine 0.6 – 1.2 High: Kidney Failure The Best indicator of kidney function. If
mg/dL this is elevated, assume renal
impairment.
WBC 5,000 – Low: Neutropenia (Risk of If < 1,000, place on "Neutropenic
10,000 infection)High: Infection Precautions" (No fresh flowers, no raw
fruit, dedicated equipment).
Platelets 150k – Low (<100k): Bleeding riskCritical If low, NO unnecessary needles, NO
400k (<50k): Hemorrhage risk aspirin, soft toothbrush only.
PT 11 – 12.5 Measures clotting (extrinsic) Used to monitor Warfarin (Coumadin)
sec therapy in conjunction with INR.
