Hypophosphatemia and Hyperphosphatemia- For Nursing Students

by | May 14, 2020 | Fluid and Electrolytes

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Hypophosphatemia & Hyperphosphatemia

Are you feeling overwhelmed with fluid and electrolytes? I can completely understand. There are several electrolytes and their associated imbalances to keep track of.

It can feel like you won’t remember it all!

The good news is that hypophosphatemia and hyperphosphatemia are probably the easiest of all the electrolyte imbalances to learn and study! I think you will understand why as you read along.

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.

Per the norm, let’s break down the words hypophosphatemia and hyperphosphatemia.

Hypo= low     phosphat= phosphorous   emia= in the blood

Hyper= high    phosphat= phosphorous    emia= in the blood

Normal phosphorous level= 3-4.5 mg/dL

Note: The normal range for phosphorous can vary. For testing purposes, use the value that your instructors and textbook give you. As a working nurse, you will use the range the facility you work at uses.

Therefore, hypophosphatemia= <3 mg/dL and hyperphosphatemia= >4.5 mg/dL

So, what is the big deal with phosphorous?

Phosphorous

Phosphorous is important in the following functions

  • Activating vitamins and enzymes
  • Forming ATP for energy supplies
  • Cell growth and metabolism
  • Calcium homeostasis

When you think about phosphorous, I want you to think ENERGY!

You likely remember learning about ATP in biology and A&P. ATP (Adenosine triphosphate) contains 3 phosphoryl groups (phosphorous + oxygen). Phosphorous is a main component of the compound (ATP) that is necessary for energy production in our body!

Phosphorous is needed for this so called “energy currency of life” (HyperPhysics) This energy is used to perform important functions in our bodies such as muscle contraction and nerve impulse transmission.

If we don’t have enough phosphorous, then we won’t have the right components to make up our energy currency. Therefore, low phosphorous=low energy.

Phosphate also plays an important role in the maintenance of strong, healthy bones.

Phosphorous is absorbed in the gastrointestinal tract, stored in the bones, and excreted by the kidneys in the form of urine.

Phosphorous is regulated through the activity of parathyroid hormone, much like calcium. However, parathyroid hormone causes a decrease in phosphorous levels as opposed to the increase that we see in calcium.

This is partly in relation to the fact that phosphorous and calcium have an inverse relationship. Therefore, when phosphorous is low then calcium will be high. When phosphorous is high then calcium will be low.

This is important to keep in mind as you study fluid and electrolytes. If you haven’t already, I would review the hypocalcemia and hypercalcemia post that I wrote up and download the free PDF cheat sheet.

Hyophosphatemia

Lab value= <3 mg/dL

Causes

(Remember, hypercalcemia=hypophosphatemia. Any mechanism that causes hypercalcemia will in turn be accompanied by hypophosphatemia.)

Malnutrition- this occurs in individuals who are in a state of starvation. These individuals are not consuming much, if any, food at all, so their phosphorous levels will be low.

Alcohol abuse– alcohol abuse can decrease the ability to absorb phosphorous in the gastrointestinal tract leading to decreased phosphorous levels.

Hyperparathyroidism– an increase in parathyroid hormone production will decrease the phosphorous levels in the blood.

Hypercalcemia– as previously mentioned, calcium and phosphorous have an inverse relationship. If calcium is high, then phosphorous will be low.

Malignancy- hypercalcemia occurs in malignancy for a variety of reasons. This hypercalcemia will be accompanied by hypophosphatemia.  

Signs/symptoms

*Remember, low phosphorous=low energy*

Decreased cardiac output, decreased stroke volume- the cardiac muscles are not working at their optimal state due to low energy. This will cause the heart to not be able to pump out blood as efficiently, so we will see decreased output and decreased stroke volume.  

Generalized weakness- the patient will be weak and report that they cannot complete their activities of daily living like they previously have been able. (Low energy)

Decreased respiratory effort- respiratory effort will be decreased due to the low energy that will decrease the efficacy of the muscles used in respirations.   

Emotional irritability- the low energy also affects nerve impulse transmission. This can cause alterations is the psychological state. You may observe the patient as being irritable or anxious.

Seizures, coma- the nerve impulse transmission in the brain will not be functioning as it normally would due to the low energy state. This could cause alterations such as seizures and coma.

Decreased bone density- as mentioned, phosphorous is stored in the bones and helps to maintain their strength and health. If phosphorous levels are low, then the bone density will decrease, as well. These patients with decreased bone density will be at an increased risk of developing fractures.

Treatment

Oral phosphorous with vitamin D supplementation- vitamin D will help increase the absorption of the phosphorous supplement in the gastrointestinal tract, thereby increasing phosphorous levels.

Dietary– if phosphorous levels are only mildly depleted, then dietary supplementation may be recommended. Phosphorous rich foods include animal sources (fish, beef, chicken, pork) and nuts

IV phosphorous- if hypophosphatemia is severe and causing serious manifestations, then IV phosphorous can be used to increase the blood levels of phosphorous.

Hyperphosphatemia

>4.5 mg/dL

Causes

Dietary- individuals who have kidney disease are at the most risk of developing hyperphosphatemia related to dietary intake. This is why many patients with chronic kidney disease will be prescribed to take Renagel 3 times a day with their meals.

Hypoparathyroidism- a reduction in parathyroid hormone secretion will cause an increased level of phosphorous in the blood

Tumor lysis syndrome- this is seen in individuals with certain types of cancers. In this condition, the cells of the tumors release their contents into the bloodstream. There are many issues that can occur from this syndrome and hyperphosphatemia (and subsequently, hypocalcemia) is one of them. This syndrome can either occur spontaneously or in response to chemotherapy.

Kidney disease- hyperphosphatemia will be seen in patients who have kidney disease due to the kidneys’ inability to excrete the excess phosphorous.

Symptoms & Treatment

The issues that occur in hyperphosphatemia are related to the accompanying hypocalcemia. Please refer to the hypocalcemia section of my post about hypocalcemia and hypercalcemia. Here you will find the symptoms, treatment, and nursing considerations associated with hypocalcemia.

The goal is to correct the hypocalcemia to increase calcium while simultaneously decreasing the phosphorous levels.

Nursing Considerations

Safety precautions should be put into place for individuals with hypophosphatemia as they are at an increased risk of experiencing a fracture.

Educate patients on foods that are high in phosphorous. Phosphorous rich foods include fish, beef, chicken, pork, and nuts. Individuals with hypophosphatemia should be encouraged to consume these foods, while patients with hyperphosphatemia should be taught to avoid such foods.

*See nursing considerations for hypocalcemia*

I hope this was helpful for you nursing students out there learning about fluid and electrolytes!

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!

Be sure to also check out my tips on how to study and pass nursing exams in nursing school, so you can pass your fluid and electrolyte exam with flying colors!

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

Happy Nursing!