Electrolyte Lab Values Practice Questions with Answers and NCLEX® Review

Monitoring electrolytes in all clients is an important nursing responsibility. Electrolyte imbalances are useful in diagnosing and treating many different medical problems.

Electrolyte Lab Values Practice Questions with Answers

{{question_current_index+1}}/{{question_max_index+1}} QUESTIONS

{{question_current_index+1}}/{{question_max_index+1}} QUESTIONS



NCLEX Answer & Rationale Overview

Learning Outcomes

NCLEX Answer & Rationale Learning Outcomes
answered correctly
answered wrongly


0% answered this

Test Taking Tips

Table of contents

    Introduction to Electrolyte Labs

    Electrolytes are minerals found in blood and body fluids that carry electrical charges. They help the body regulate chemical reactions and maintain the balance between fluids inside and outside the cell.

    Electrolyte lab values help determine whether your client is dehydrated or needs rehydrating.
    If one or more of these electrolytes become imbalanced in the body, it can cause serious problems. Electrolyte imbalances can be dangerous if left untreated, and can result in shock or cardiac arrhythmia. It’s a key nursing responsibility to be familiar with electrolyte values.

    When electrolytes are in homeostasis (maintained at the normal values), the more efficient the kidneys are at filtering out toxins. But if a client has chronic kidney disease and doesn’t get enough electrolytes, it can make the kidneys less efficient at filtering out waste products from the body. One of the functions of healthy kidneys is to filter blood and remove waste products such as urea from the body.

    The six electrolytes include:

    • Sodium (Na+)
    • Potassium (K+)
    • Chloride (Cl-)
    • Calcium (Ca2+)
    • Magnesium (Mg2+)
    • Phosphate (P)
    Are you
    to take the

    Normal Electrolyte Lab Values

    Sodium: 135 to 145 mmol/L
    Priority, Pumps the Heart

    Potassium: 3.5 to 5.0 mmol/L
    Maintains blood pressure, blood volume, and pH balance

    Calcium: 8.5 to 10.2 mg/dL (in adults)
    Keeps the 3 Bs Strong: Bone, Blood (clotting), and Beats (heart)

    Chloride: 97 to 107 mmol/L
    Maintains blood pressure, blood volume, and pH balance

    Magnesium: 1.3 to 2.1 mg/dL
    Mellows the muscles

    Phosphate: 3.0 to 4.5 mg/dL
    When Ca is high = Phosphate is low – and when Ca is low = Phosphate is high

    Electrolyte Imbalances (with Lab Values & Memory Tricks)

    When a client’s electrolytes are imbalanced, it affects the body’s processes. For example, if the client has low potassium levels, it can cause muscle weakness and heart arrhythmias.

    These imbalanced levels of electrolytes result in hyper or hypo conditions, such as hypercalcemia (too much calcium) and hyponatremia (too little sodium).

    ElectrolytesHigh (Hyper)Low (Hypo)
    Potassium K+Hyperkalemia (over 5.0)Hypokalemia (below 3.0)
    Sodium Na+Hypernatremia (over 145)Hyponatremia (below 135)
    Chloride Cl-Hyperchloremia (over 107)Hypochloremia (below 97)
    Magnesium Mg+Hypermagnesemia (over 2.1)Hypomagnesemia (below 1.3)
    Calcium CaHypercalcemia (over 10.5)Hypocalcemia (below 9.0)
    Phosphate PHyperphosphatemia (over 4.5)Hypophosphatemia (below 3.0)

    Hyponatremia Pathophysiology

    Hyponatremia is an electrolyte imbalance (below 135 Na+) caused by water intoxication. Water intoxication occurs when someone drinks so much water that it dilutes the sodium in the blood and overwhelms the kidney’s compensation mechanism). 

    It can also be caused by a syndrome of inappropriate antidiuretic hormone secretion (SIADH). SIADH is associated with conditions such as pneumonia, brain diseases, cancer, thyroid problems, and taking some medications.

    Hyponatremia Causes

    • Sweating
    • Excess water intake
    • Running in extreme heat
    • SIADH 
    • Vomiting and diarrhea
    • Diuretics and Diuresis
    • Diets low in salt
    • Low aldosterone

    Hyponatremia Signs and Symptoms

    • Brain is low and slow
      • Headache = Cerebral edema
      • Mental status changes
      • Seizures and coma
    • Muscular = low and slow
      • Fatigue and muscle cramps
    • Respiratory = low and slow
      • Respiratory arrest

    Hyponatremia Nursing Interventions

    • Monitor fluid volume status.
    • Administer IV fluids and medications as ordered.
    • Encourage eating foods and fluids with sodium (salt).
    • Assess weight and skin turgor (to identify dehydration).
    • Practice seizure precautions.

    Hypernatremia Pathophysiology

    Hypernatremia (over 145 Na+) occurs when there is too little water, instead of too much sodium, in the body. This water loss can result from illness with vomiting or diarrhea, excessive sweating from exercise or fever, or from drinking fluid that has too high concentrations of salt. 

    Hypernatremia Causes

    • Low ADH (antidiuretic hormone)
    • DI: Diabetes Insipidus
    • Rapid respirations
    • Watery diarrhea
    • Loss of thirst

    Hypernatremia Signs and Symptoms

    • Body = big and bloated 
    • Edema (swollen body)
    • Flushed “red & rosey” skin
    • Increased muscle tone
    • Swollen dry tongue
    • Nausea & Vomiting

    Chronic Kidney Disease

    The kidneys are responsible for filtering waste products out of the blood and into urine. They also help to maintain the balance of electrolytes in the body. If the kidneys become damaged, they can no longer perform these functions effectively, which can lead to chronic renal failure and other complications.

    When a client has Chronic Kidney Disease (CKD), the kidneys can’t get rid of electrolytes.

    Chronic kidney disease can lead to high blood pressure and associated heart disease and stroke risks. It also increases the risk of developing osteoporosis and muscle weakness due to low potassium levels, which are associated with increased fall risk among older adults.

    Photo of Amy Stricklen
    Amy Stricklen

    During my exam, I could literally see and hear him going over different areas as I was answering my questions.

    This past Friday I retook my Maternity Hesi and this time, I decided for my last week of Holiday break to just watch all of his OB videos. I am proud to say that with Mike’s help I received a score of 928 on my Maternity Hesi!

    Photo of Amy Stricklen
    Amy Stricklen

    Electrolyte Labs Conclusion

    Electrolytes are an essential part of how the body functions. They affect everything from hydration to the heart. They also help the health care provider (HCP) to be able to diagnose a wide variety of medical conditions. A nursing responsibility is understanding electrolytes and how they affect the body, along with normal lab values and interventions that can impact client care.



    Need help with your next exam? Our proven system has helped over 1,000,000 nursing students reduce their study time, survive their nursing school lectures and PASS their exams! SimpleNursing membership offers:

    • 1,100 fun and visual videos covering the most highly tested topics in RN/PN nursing programs
    • 900+ pages of cheat sheets & done-for-you study guides
    • Test tips and memory tricks included
    See how our members are
    earning a 99% pass rate.
    Get started now For Free