What is Vitamin D Toxicity?
Vitamin D is a type of vitamin that can be found in certain animal products and specially fortified foods, and our bodies also produce it naturally. Not only can you get Vitamin D from diet and sunlight, but it’s also available as a prescription supplement or one that you can buy over the counter. One of the main purposes of Vitamin D is to help keep bones healthy, as not having enough can result in diseases like rickets and osteopenia. In addition to that, recent studies have shown that Vitamin D also helps with several metabolic processes and can impact conditions like autoimmune disease, cancer, heart disease, depression, dementia, infectious diseases, and musculoskeletal decline. Luckily, it is now easier to prevent Vitamin D deficiency because of the availability of fortified foods and supplements.
A Vitamin D overdose, or hypervitaminosis D, isn’t common. It generally happens when someone takes more than the recommended dose of over-the-counter Vitamin D supplements or is given the wrong prescription. Less frequently, exposure to certain rodent killers containing cholecalciferol can cause an overdose of Vitamin D. High Vitamin D levels can cause toxicity leading to an too much calcium in our body, which can upset the normal function of bone metabolism and cause hypercalcemia – an excessive amount of calcium in your blood – along with its related signs and symptoms.
What Causes Vitamin D Toxicity?
Vitamin D toxicity, or taking too much vitamin D, can happen when people consume excessive doses of vitamin D supplements, either intentionally or by mistake. This can also happen when prescriptions are filled incorrectly without frequent check-ups to monitor vitamin D levels. This type of toxicity is often seen in patients who require high doses of vitamin D to treat conditions like osteoporosis, kidney disease, psoriasis, or problems related to gastric bypass surgery, celiac disease, or inflammatory bowel disease.
Sometimes, foods or supplements contain more vitamin D than intended, which can lead to toxicity. For example, in 2015, the FDA recalled a type of multivitamin due to excessive amounts of vitamin D. Similarly, in 2016, a health supplement in Denmark was recalled because it had 75 times the recommended dose of vitamin D, causing toxicity in at least 20 children.
Certain foods like fish, meat, and dairy products contain vitamin D, but usually not in amounts that can cause toxicity. However, those who are taking high doses of vitamin D and consuming large amounts of highly fortified milk are at a higher risk for vitamin D toxicity. Some medical conditions, such as certain immune disorders and types of cancer, can also result in excessive production of vitamin D and lead to toxicity.
Unlike supplements, getting too much sun doesn’t cause vitamin D toxicity because the body naturally regulates and converts Vitamin D into inactive forms.
Interestingly, cholecalciferol, a form of vitamin D found in certain rat poisons, has been reported to cause vitamin D toxicity, although this is mainly seen in animals.
Risk Factors and Frequency for Vitamin D Toxicity
Between 2000 and 2014, a whopping 25,397 cases of vitamin D overdose were reported. The yearly average was 196 cases from 2000 to 2005. But from 2005 to 2011, the number of vitamin D overdoses shot up by an enormous 1600%, creating a new yearly average of 4,535 cases.
As per the latest data from America’s Poison Centers, the National Poison Data System recorded 11,718 instances of vitamin D exposure. More than half of these were children younger than 5. The majority of cases happened accidentally. Surprisingly, there were more cases of vitamin D overdose than overdoses of vitamins B, A, C, and E combined. This points to the widespread use of vitamin D supplements.
Signs and Symptoms of Vitamin D Toxicity
Vitamin D toxicity is diagnosed through a detailed review of a person’s medical history, including the use of any over-the-counter supplements. Certain conditions such as osteoporosis, kidney disease, psoriasis, post-gastric bypass surgery, and digestive disorders like celiac or inflammatory bowel disease might require high doses of vitamin D supplementation. Therefore, these details need to be considered. Also, individuals consuming excessive vitamin D-enriched milk and additional vitamin D supplements should also be examined.
The signs and symptoms of vitamin D toxicity are mainly due to high calcium levels in the blood, also known as hypercalcemia. These symptoms range from nonspecific to severe. Mild symptoms generally include weakness, fatigue, loss of appetite, and bone pains. On the severe end, neurological symptoms like confusion, apathy, agitation, irritability, and in some cases, loss of balance, stupor, and coma can occur. Common digestive problems involve abdominal pain, nausea, vomiting, constipation, peptic ulcers, and pancreatitis. The kidneys can also be affected, causing increased urination, intense thirst, and kidney stones. Serious cases of hypercalcemia can lead to irregular heartbeats.
Physical check-ups may show signs of dehydration, like loss of skin elasticity and dryness of the mucous membranes; changes in mental status; and abdominal tenderness without any protective muscle spasm, rigidity, or guarding reflex. However, sometimes, the physical exam might not show any specific signs. In such situations, historical information should guide the level of suspicion for vitamin D toxicity.
Testing for Vitamin D Toxicity
Determining if a patient has too much vitamin D in their body is done through reviewing their medical history and the symptoms they are experiencing. From a laboratory perspective, the patient’s calcium, ionized calcium, phosphate levels, and parathyroid hormone levels are checked. Usually, a high calcium level and lower parathyroid hormone levels can be a sign of vitamin D toxicity.
More in-depth testing might reveal that a part of the vitamin D molecule, known as the 25(OH)D concentration, is over 150 ng/mL. This can sometimes be accompanied by another form of the vitamin D molecule, 1,25(OH)2D, being at normal or elevated levels. Patients with diseases that produce granules of inflammation may also show heightened 1,25(OH)2D levels, even if the 25(OH)D concentration is at normal levels.
Additionally, a basic check-up of the body’s chemistry is important for understanding the effects of too much Vitamin D on the kidneys, and for checking any potential issues with the body’s electrolyte levels from constant vomiting.
An EKG, a test that checks how the heart is functioning, may also show signs of vitamin D toxicity. This includes a shortening of the time it takes for the heart to contract and relax between beats. Other findings may include a longer time it takes for the electrical signals to travel through the heart’s upper chambers, a shortened period of time of the last phase of the heart’s electrical activity, and flattened waves that show the heart’s electrical activity.
Images, like X-rays or CT scans, aren’t usually necessary to confirm vitamin D toxicity. However, they can show signs of long-term damage, such as build-up of calcium in various parts of the body. This can be seen in the formation of too much bone tissue around the original bone, the formation of stones in the kidney, or the formation of calcium deposits in arteries, heart muscle, the lungs, or the skin. If the patient is confused or not thinking clearly, a CT scan of the brain might be a good idea to check for other causes for these symptoms.
Treatment Options for Vitamin D Toxicity
If a person has too much vitamin D in their body, the main goal of treatment is to reduce their calcium levels. Here’s how:
First, stop taking vitamin D and calcium supplements. Also, avoid spending too much time in bed, as this could lead to high calcium levels due to lack of movement.
If dehydrated, use a saline solution (a mixture of salt and water) to help restore normal hydration levels and aid the kidneys in removing excess calcium.
For severe cases of vitamin D overdose, where calcium levels exceed 14 gm/dL, two medicines, calcitonin and bisphosphonates, can be used. Calcitonin can be given as a 4 U/kg injection every 12 hours for 48 hours. Intravenous bisphosphonates can also be given; 90 mg of Pamidronate over 2 hours or 4 mg of zoledronic acid over 15 minutes.
Using calcitonin and bisphosphonates together has been found to boost the effectiveness of calcitonin. However, calcitonin may become less effective over time, while bisphosphonates can keep on working for a longer period. While on these medications, it’s crucial to monitor calcium levels closely. The use of intravenous glucocorticoids, which reduce calcium levels by lowering a particular form of vitamin D and increasing calcium excretion in the urine, is a debated treatment approach generally saved for vitamin D toxicity related to certain diseases.
A dose of either 100 mg of Hydrocortisone per day or 40 mg of Prednisone daily for 5 days is typically the recommended regimen. People with severe vitamin D toxicity may need treatment with hemodialysis – a procedure that helps cleanse the blood – either due to kidney failure or to manage high levels of calcium that are not responding to other treatment approaches.
It’s also necessary to review and adjust the victim’s list of daily medications, particularly the dose of any vitamin D supplement. Make sure to talk to the patient about the risks associated with overusing vitamin supplements. The Endocrine Society further recommends that anyone on high-dose vitamin D treatment should have their calcium and vitamin D levels regularly checked.
What else can Vitamin D Toxicity be?
If someone has too much vitamin D in their body, it’s important for doctors to ensure this is the actual cause and not a result of something else. The symptoms of vitamin D overdose can be similar to many other health conditions, such as:
- Hypercalcemia due to cancer
- Hypercalcemia from diseases causing inflammation
- Hyperparathyroidism, which is an overactivity of the parathyroid glands
- Vitamin A overdose
- Thyrotoxicosis, an excess of thyroid hormone
- Paget’s disease, a condition that disrupts the normal replacement of old bone tissue with new bone tissue
- Hypercalcemia caused by not being able to move for a long time
- Milk-alkali syndrome, a condition caused by consuming too much calcium and absorbable alkali
It is crucial for the doctor to examine these possibilities to make an accurate diagnosis.
What to expect with Vitamin D Toxicity
Generally, most instances of too much vitamin D in the body are resolved without severe consequences or long-term effects. However, in some cases, having extremely high levels of calcium in the blood due to vitamin D toxicity can cause sudden kidney failure that needs dialysis. Rarely, permanent kidney damage can occur as a result of vitamin D toxicity.
Possible Complications When Diagnosed with Vitamin D Toxicity
In rare cases, having too much vitamin D (a condition known as vitamin D toxicity) can lead to kidney failure, which might require a treatment called hemodialysis.
Preventing Vitamin D Toxicity
Helping patients to understand the risks of overusing vitamin D supplements is very important. Patients, especially those prescribed high doses of vitamin D, need to be informed about the value of sticking to their recommended dosage for treating their health conditions effectively. Also, patients should know why attending regular check-ups is essential when taking large amounts of vitamin D supplements to prevent overdose.
Sometimes, having tests to check calcium and vitamin D levels in your body can be useful for keeping track of the situation. Understanding and implementing this information will ensure a healthier and safer usage of vitamin D supplements.
