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Hypocalcemia & Hypercalcemia

Next up in our fluid and electrolyte series is hypocalcemia and hypercalcemia. This was actually my favorite (if you can have a favorite electrolyte imbalance) in nursing school because I actually experienced hypercalcemia whenever I was a child. I had a parathyroid adenoma that resulted in severely elevated blood calcium levels. This personal experience made it an easy subject to study and remember.

Hopefully, my personal experience can also help make this an easy topic for you to study and learn too!

Once you read all the information in this post, be sure to download this PDF cheat sheet that outlines the highlights contained in this post.

Let us begin by breaking down the words “hypocalcemia” and “hypercalcemia”.

Hypo= low calc= calcium emia= in the blood

Hyper= high calc=calcium emia= in the blood

Hypocalcemia= low calcium levels in the blood

Hypercalcemia= high calcium levels in the blood

The normal lab value for calcium in the blood is 9-10.5 mg/dL.

Therefore, hypocalcemia is defined as <9 mg/dL and hypercalcemia is >10.5 mg/dL

Calcium

Calcium helps maintain bone strength and density, allows nerve impulse transmission, maintains muscle tone, and is important in blood clotting.

Vitamin D must be present in order for calcium to be absorbed.

Whenever calcium is low, increased parathyroid hormone is secreted by the parathyroid

• Calcium is pulled from bone storage and placed in the bloodstream
• Vitamin D absorption is stimulated
• Kidney excretion of calcium is inhibited

When calcium levels are high, thyrocalcitonin is secreted by the thyroid

• Bone resorption is inhibited
• Vitamin d absorption is inhibited
• Kidney excretion of calcium is promoted

An important note to make about hypocalcemia and hypercalcemia is that there is a paradox that is present. One might expect that since calcium is essential to regulate nerve transmission and muscle contraction that not enough calcium would cause a decreased response, while too much calcium would cause an increased response.

However, the opposite is true. There is an unexplained inverse relationship between the amount of calcium and the excitability of nerves and muscles.

Hypocalcemia= increased excitability

Hypercalcemia= decreased excitability

This will be important to keep in mind when studying the signs and symptoms that will be seen in patients who have a calcium imbalance. You will notice I remind you of this concept many times…I am sorry in advance.

Another concept to take note of is calcium and phosphorous’s inverse relationship. So, when calcium is high, then phosphorous is low. And when phosphorous is high, calcium is low.

Hypocalcemia

<9 mg/dL

Here is a video version of all the information in this post pertaining to hypocalcemia if you would rather learn about hypocalcemia in video form.

Causes:

• Dietary/malabsorption- If the patient has a malabsorption disorder of the intestines, then they will not be able to absorb the vitamins and nutrients from food as they normally would. This could include disorders such as Celiac disease or Crohn’s disease. This could cause a lack of Vitamin D and calcium absorption in the intestines. Also, if there is inadequate dietary intake of calcium that is sustained over a period of time, then hypocalcemia can result.

• Parathyroid removal, hypoparathyroidism- remember, the parathyroid normally secretes parathyroid hormone whenever calcium levels are low. This secretion signals the body in several different ways to effectively increase the blood level of calcium. If one or more parathyroid nodules are removed or diseased, then the regulatory system is not going to be functioning properly. This will cause the calcium levels to remain decreased.

• Vitamin D deficiency– vitamin D, when ingested or absorbed through the skin from sunlight, increases the absorption of calcium. If someone is vitamin D deficient, then they run the risk of developing hypocalcemia because calcium absorption will be decreased.

• Polyuric phase in kidney failure- calcium is excreted in the urine, so if a patient is experiencing a large amount of urine excretion, then there is an increased risk of hypocalcemia.

• End stage kidney disease– patients who have chronic kidney disease (CKD) will experience increased phosphorous levels in their blood. As mentioned earlier, phosphorous and calcium have an inverse relationship. Since the phosphorous level is high, then the calcium level will be low.

• Calcium chelators- these agents bind to calcium to form a compound that is then excreted. This excretion of calcium can then cause hypocalcemia.

Signs/symptoms:

*Remember, hypocalcemia=increased excitability of nerves and muscles*

• Hyperactive DTRs, muscle spasms, muscle twitching– increased excitability of muscles causes hyperactive deep tendon reflexes, muscle spasms, and muscle twitching.

• Trousseau’s sign– this is a carpal spasm that occurs when a blood pressure cuff is inflated on the arm due to increased muscle excitability.

• Chvostek’s sign– this is a twitching of facial muscles whenever the patient’s face is lightly tapped over the facial nerve due to increased muscle excitability

• Increased intestinal peristalsis– causing diarrhea and abdominal cramping due to the smooth muscle of the intestines undergoing increased excitability

• ECG changes, hypotension, decreased heart rate- ECG changes include prolonged ST interval and prolonged QT interval

• Paresthesia- an abnormal sensation of tingling or numbness- this sensation is being caused by nerves which are experiencing increased excitability

• Brittle, fragile bones- calcium is what helps make our bones strong. If there is not enough calcium to do this, then the bones will become fragile and brittle. This increases the risk of developing a fracture.

• Seizures- the neurons in our brain are experiencing increased excitability so this “uncontrolled electrical disturbance in the brain” (MayoClinic) occurs

Treatment

• Phosphate binders- as mentioned earlier, calcium and phosphate have an inverse relationship. If phosphate binders are administered, then the phosphate level would decrease as the calcium level increases

• Oral and IV calcium replacement- oral or IV calcium replacement can be used to increase the amount of calcium in the blood. The severity of the hypocalcemia as well as the manifestations the patient is experiencing will dictate if oral or IV calcium replacement is utilized.

• Magnesium sulfate- magnesium sulfate can be used to combat severe neuromuscular alterations. This medication will not lower the blood calcium level, however.

Hypercalcemia

>10.5 mg/dL

Here is a video version of all the information in this post pertaining to hypercalcemia if you would rather learn about hypercalcemia in video form.

Causes:

• Hyperparathyroidism- if the parathyroid normally increases the amount of calcium in the blood by secreting parathyroid hormone (PTH), then if we have an overactive parathyroid, then we will see an inappropriate increase in the amount of calcium that is pulled into the bloodstream.

• Thiazide diuretics- these diuretics cause the body to retain calcium, thereby increasing the risk of hypercalcemia

• Malignancy- there are a few different mechanisms that cause hypercalcemia to occur in cancer. The main take away is that osteoclast activity is often increased by hormones released by the tumor involved in the cancer. This then causes the calcium that was in the bone to be transferred to the bloodstream, thereby increasing the blood calcium levels. If you are interested in the detailed information regarding this process, check out this article.

• Immobility- for the calcium to stay inside the bones, those bones need to be moving! If a patient is immobile for a period of time, then the calcium will leak into the bloodstream and increase blood levels of calcium

• Vitamin D excess-although this is not a common issue, since vitamin D is a fat-soluble vitamin, it can build up in your body over time. If there is too much Vitamin D, then the amount of calcium that is absorbed will increase, thereby causing hypercalcemia

• Dehyrdration– dehydration causes the blood to become more concentrated with calcium

Signs/symptoms:

*Remember, hypercalcemia= decreased excitability of nerves and muscles*

• Hypoactive DTRs, severe muscle weakness- the decreased excitability causes the deep tendon reflexes to be hypoactive or absent and the patient will experience severe muscle weakness

• Decreased intestinal peristalsis- causing constipation, N/V, and abdominal pain due to the decreased excitability of the smooth muscle of the intestines.

• Cardiac alterations, ECG changes- in the early stages, the patient will experience an increase in heart rate. As the hypercalcemia worsens, the heart rate decreases which could lead to cardiac arrest. ECG changes include shortened ST segment and widened T wave

• Impaired blood flow- blood clot formation can occur due to this impaired blood flow. Impaired blood flow could present as cyanosis, pallor, or decreased capillary refill.

• Altered LOC- lethargy and coma can occur due to decreased excitability of nervous tissue.

Treatment

• Calcium chelators- these agents cause calcium to be excreted in the urine, thereby decreasing the blood levels of calcium.

• Re-hydration- IV NS 0.9%– this helps hydrate patients who experienced dehydration as well as prevents patients from developing kidney stones (since kidney stones are sometimes formed during hypercalcemia).

• Furosemide- if a patient needs a diuretic, then furosemide would be an appropriate diuretic to use as it causes calcium to be excreted in the urine. Of course, any thiazide diuretics that were being used should be discontinued.

• Dialysis- dialysis may need to be initiated to filter the excess calcium out of the blood.

Nursing Considerations

Seizure precautions for hypocalcemia

• Quiet room with dim lights, keep noise to a minimum
• Oxygen and suction at bedside
• IV access
• Bed in lowest position, mattress on floor beside the bed

Infuse calcium IV slowly, patient should be on cardiac monitoring

Teach patients about foods that are high in calcium. Dairy is well known for being high in calcium- milk, yogurt, cheese. Encourage patients with hypocalcemia to eat these types of foods, while teaching patients with hypercalcemia to avoid these foods.

Menopausal women are at an increased risk for hypocalcemia, therefore may experience brittle and fragile bones. All patients with hypocalcemia should be handled with care during repositioning, transferring, and ambulating. They are at increased risk of sustaining a fracture if injury were to occur.

If you haven’t already checked out my other posts on the other fluid and electrolyte imbalances, you can click the links below to be taken to each of the individual posts. Each of them have a downloadable cheat sheet so be sure to grab those!

• Hyponatremia & hypernatremia
• Hypokalemia & hyperkalemia
• Hypomagnesemia & hypermagnesemia
• Hypophosphatemia & hyperphosphatemia

As always, feel free to contact me if you have any questions!

Happy Nursing!