Lippincott Nursing Pocket Card - March 2021

Quick Guide to Laboratory Values


About this Pocket Card

Use this convenient cheat-sheet to help you monitor laboratory values related to fluid and electrolyte status. Remember, normal value ranges may vary according to techniques used in different laboratories.


Serum Electrolytes

Nursing Considerations
Calcium (Ca2+)
8.5-10.5 mg/dL
  • Signs and symptoms
    • Seizures, neuromuscular irritability or tetany (may include paresthesia, bronchospasm, laryngospasm, carpopedal spasm [Trousseau’s sign], Chvostek’s sign [facial muscle contractions elicited by tapping facial nerve on ipsilateral side], tingling sensations of the fingers, mouth, and feet, increased deep tendon reflexes [DTRs]), bleeding abnormalities
    • ECG changes may include prolonged QT interval and arrythmias.
  • Implement seizure precautions and close monitoring of respiratory status.
  • Signs and symptoms
    • Lethargy, confusion, nausea, vomiting, anorexia, constipation, muscle weakness, depressed DTRs
  • Monitor cardiac rate and rhythm.
  • Increase mobilization, provide adequate hydration either with IV fluids or encouragement of oral intake.
  • Watch for digitalis toxicity.
Chloride (Cl-)
97-107 mEq/L
  • Signs and symptoms
    • Muscle spasms, alkalosis, and depressed respirations
  • May be precipitated or exacerbated by GI losses (vomiting, diarrhea).
  • Monitor for acidosis.
Magnesium (Mg2+)
1.8-3 mg/dL
  • Signs and symptoms
    • Cardiac/ventricular arrhythmias, laryngeal stridor/spasm, neuromuscular disturbances
  • Risk factors: chronic diarrhea, PPI use, alcoholism, diuretic use
  • Implement seizure precautions.
  • Monitor cardiac rate and rhythm.
  • Monitor for digitalis toxicity.
  • Signs and symptoms
    • Early: nausea, vomiting, flushing
    • Cardiac: hypotension, bradycardia, complete heart block, cardiac arrest
    • Neurologic: lethargy/somnolence, decreased DTRs, muscle paralysis, coma, respiratory muscle weakness (shallow respirations, apnea)
  • Avoid Mg-containing medications in patients with compromised renal function.
  • Monitor cardiac rate and rhythm.
  • Monitor neurologic status, including DTRs.
Phosphate (PO4-)
2.5-4.5 mg/dL
  • Signs and symptoms (rare unless PO4- < 1mg/dL)
    • Muscle weakness, rhabdomyolysis
  • Treatment indicated when PO4- < 2mg/dL.
  • Oral replacement preferred.
  • IV indicated if PO4- < 1mg/dL; administer slowly.
  • Administer IV phosphate products and parenteral nutrition (PN) cautiously.
  • Monitor for hypocalcemia, renal failure, arrhythmias, and diarrhea (with oral replacement).
  • Monitor for signs and symptoms of infection.
  • Signs and symptoms
    • Typically asymptomatic
    • May have tetany if hypocalcemia also present
  • Soft tissue calcification can be a long-term complication of chronically elevated serum phosphate levels.
  • More common in those with advanced renal insufficiency.
Potassium (K+)
3.5-5 mEq/L
  • Signs and symptoms
    • Muscle cramps/weakness, rhabdomyolysis, respiratory muscle weakness, decreased bowel motility, cardiac arrythmias, hypotension, mental status changes, speech changes
  • Characteristic ECG findings include ST segment depression, flattened T wave and U wave.
  • Monitor cardiac rate and rhythm.
  • Common causes include GI losses (diarrhea/vomiting) and diuretic therapy.
    • Educate patient on using laxatives and diuretics only as prescribed.
  • Monitor potassium levels in patients on digoxin; hypokalemia will potentiate its effects.
  • Signs and symptoms
    • Irritability/anxiety, paresthesias, ascending muscle weakness, cardiac arrhythmias, cardiac conduction abnormalities, lethargy, GI symptoms (nausea and intestinal colic)
  • Characteristic ECG findings include tall, peaked T waves with shortened QT interval, prolonged PR interval, wide QRS complex and in severe cases, ventricular standstill.
  • Monitor cardiac rate and rhythm.
  • Avoid potassium-sparing diuretics, potassium supplements, or salt substitutes in patients with renal insufficiency.
  • Use ACE inhibitors cautiously, as they cause K+ retention.
Sodium (Na+)
135-145 mEq/L
  • Signs and symptoms
    • Neurologic: lethargy, weakness, irritability, confusion, tremors, myoclonus, seizure
    • Other: hypotension, GI symptoms (anorexia, nausea, vomiting, abdominal cramping)
  • Correction should be slow (4 to 6 mEq/L in first 24 hours) to avoid osmotic demyelination syndrome; monitor serum Na+ levels and neurologic status frequently.
  • Avoid large water supplements to patients receiving isotonic tube feedings.
  • Implement seizure precautions in severe cases.
  • Monitor fluid losses and gains.
  • Signs and symptoms
    • Excessive thirst, dehydration, dry mucous membranes, oliguria, mental status changes including lethargy, disorientation, restlessness, elevated body temperature
  • Monitor fluid losses and gains; urine and plasma osmolality may assist in establishing etiology.
  • Give sufficient free water with tube feedings or salt-free IV fluids to keep serum Na+ and BUN within normal limits.

Arterial Blood Gas (ABG) Component
Nursing Considerations


  • Identification of the specific acid–base disturbance is important in identifying the underlying cause of the disorder and determining appropriate treatment.
  • A pH less than 7.35 indicates acidosis and a pH greater than 7.45 indicates alkalosis.
35-45 mmHg
  • The PaCO2 is influenced almost entirely by respiratory activity.
  • When the PaCO2 is low, carbonic acid leaves the body in excessive amounts; when the PaCO2 is high, there are excessive amounts of carbonic acid in the body.
22-26 mEq/L
  • The bicarbonate level of the ABG reflects the bicarbonate level of the body.
  • The kidneys are involved in either reabsorbing bicarbonate or excreting bicarbonate, depending upon what is needed to maintain acid-base balance.
Laboratory Value
Nursing Considerations

Blood urea nitrogen (BUN)
10-20 mg/dL

  • Increased BUN may be seen in patients with impaired renal function.
  • Increased BUN may be caused by hypotension/shock, heart failure, and salt and water depletion), diabetic ketoacidosis, and burns.
0.7-1.4 mg/dL
  • Increased creatinine levels may be seen in patients with impaired renal function due to decreased blood flow to the kidney (heart failure, shock, liver disease, dehydration), urinary tract obstruction, intrinsic kidney disease (i.e., glomerulonephritis), or certain medications.
  • ​Acute kidney injury (AKI) is diagnosed when baseline creatinine increases abruptly by ≥ 0.3 mg/dL, even if creatine remains in the normal range.
Laboratory Value
Nursing Considerations

Males: 13-18 g/dL
Females: 12-16 g/dL

  • Increased hemoglobin levels may be caused by hypoxia, high altitude living, or hemoconcentration of the blood from dehydration.
  • Decreased levels of hemoglobin (anemia) may be due to hemorrhage/blood loss, hemodilution, nutritional deficiencies, chronic kidney disease, underlying malignancy, hereditary disorders, or a hemolytic reaction.
*typically, three times the hemoglobin level
Males: 42-52%
Females: 35-47%
  • Increased hematocrit values are seen in severe fluid volume deficit and shock (when hemoconcentration rises considerably).
  • Decreased hematocrit values are seen with blood loss, hemolytic reactions after transfusion of incompatible blood, fluid overload, and in similar conditions in which decreased levels of hemoglobin are seen.
Platelet count
  • Increased platelet levels (thrombocythemia or thrombocytosis) may be caused by a bone marrow disorder or malignancy, infection or inflammation, anemia, splenectomy, or certain medications.
  •  Decreased platelet levels (thrombocytopenia) may be a result of bone marrow suppression, sequestration from an enlarged spleen, increased platelet destruction (seen with autoimmune syndromes or drug-induced reactions), or decreased platelet production (related to infections or malignancy). Liver disease, renal disorders, and pregnancy can also cause thrombocytopenia.
Laboratory Value
Nursing Considerations

Prothrombin time (PT)
9.5-12 seconds

  • The PT measures the activity of the extrinsic pathway of the clotting cascade and can be used to monitor the level of anticoagulation.
Partial thromboplastin time (activated) (PTT)
20-39 seconds
  • The PTT is a measure of the activity of the intrinsic pathway of the clotting cascade.
  • The PTT is used to monitor the effects of unfractionated heparin.
International normalized ratio (INR)
1.0; 2-3.5 for patients taking warfarin sodium (varies based on diagnosis)
  • The INR is used to monitor the effectiveness of warfarin therapy.
  • As INR increases, time for blood to clot increases.
Laboratory Value
Nursing Considerations

Total protein
6-8 g/100 mL

  • Proteins influence the colloid osmotic pressure.
  • Includes albumin and globulin.
3.5-5 g/100 mL
  • Makes up 60% of total protein.
  • Keeps fluid from leaking out of blood vessels.
  • Changes in serum albumin affect total serum calcium.
  • Decreased albumin can be due to malnutrition or liver disease and can lead to edema, ascites, and pulmonary edema.
Laboratory Value
Nursing Considerations

280-300 mOsm/L water

  • Increased osmolality may be caused by severe dehydration, free water loss, diabetes insipidus, high hypernatremia, hyperglycemia, stroke or head injury, renal tubular necrosis, or ingestion of methanol or ethylene glycol (antifreeze).
  • Decreased osmolality may be caused by volume excess, SIADH, renal failure, diuretic use, adrenal insufficiency, hyponatremia, overhydration, or paraneoplastic syndrome associated with lung cancer.
Laboratory Value
Nursing Considerations

pH (urine)

  • Decreased urine pH may be caused by metabolic acidosis, diabetic ketoacidosis, or diarrhea.
  • Increased urine pH may be caused by respiratory alkalosis, potassium depletion, or chronic renal failure.
Specific gravity (urine)
  • The urine specific gravity range depends on the patient’s state of hydration and varies with urine volume and the load of solutes to be excreted.
  • Increased urine specific gravity may be seen with dehydration, vomiting, diarrhea, infection, and heart failure.
  • Decreased urine specific gravity can occur with renal damage.


Greenberg, E. (2017). Thrombocytopenia: A Destruction of Platelets. Journal of Infusion Nursing, 40(1), 41-50.
Hankins J. (2006). The role of albumin in fluid and electrolyte balance. Journal of Infusion Nursing, 29(5), 260–265.
Hinkle, J., & Cheever, K. (2018). Brunner & Suddarth’s Textbook of Medical-Surgical Nursing, Fourteenth Edition. Philadelphia: Lippincott Williams & Wilkins.
Mount, D. B. (2019, December 2). Clinical manifestations and treatment of hypokalemia in adults. UpToDate.
Mount, D. B. (2020, March 9). Clinical manifestations of hyperkalemia in adults. UpToDate.
Yu, A. S., & Aditi, G. (2020, August 20). Hypermagnesemia: Causes, symptoms, and treatment. UpToDate.
Yu, A. S., & Stubbs, J. R. (2019, May 22). Hypophosphatemia: Evaluation and treatment. UpToDate.