What is Vitamin A Toxicity?
Vitamin A is vital for various body functions such as vision, cell division, reproduction, and the immune system. It falls under a group of fat-dissolvable substances known as retinoic acids. Beta-carotene is a well-known type of vitamin A, and it actually comes in two important forms: preformed vitamin A and provitamin A carotenoids. Animals, including humans, transform these carotenoids into active vitamin A. Preformed vitamin A includes active compounds like retinol, retinal, retinoic acid, and retinyl esters.
Though it’s crucial for our health, too much preformed vitamin A can cause both immediate and long-term harmful effects. When your body has too much vitamin A, it’s known as hypervitaminosis A. In addition, vitamin A is acknowledged as a teratogen, meaning it can cause severe deformities. This text discusses how to prevent, identify, and treat the three main types of vitamin A toxicity: acute (short-term), chronic (long-term), and teratogenic (causing malformations).
What Causes Vitamin A Toxicity?
Hypervitaminosis A, which is an unusual condition caused by having too much vitamin A in your body, typically comes about due to overuse of supplements or certain medications. The main reason for this toxicity is due to people eating large amounts of foods and dietary supplements that contain very high levels of vitamin A, often without the right medical oversight.
Our diets usually contain a mix of preformed vitamin A and carotenoids that can turn into vitamin A, known as provitamin A. Preformed vitamin A comes from animals and can be found in food like egg yolks, butter, chicken, beef, fish, organ meats and foods that have been fortified with it. Because our bodies easily absorb preformed vitamin A in the small intestine, and then store it in the liver, eating a lot of this type of vitamin A from animal-based foods and supplements can lead to toxicity.
Pro-vitamin A carotenoids are found in plants, like leafy greens and brightly-colored fruits and vegetables, such as carrots, sweet potatoes, and papayas. These substances are converted into active vitamin A in our bodies. While the absorption of provitamin A can vary, our bodies naturally regulate how much is absorbed. This makes it unlikely that eating too much of these types of foods will lead to toxicity.
It’s also worth pointing out that certain skin medications contain compounds that are similar to vitamin A. Using these medications too much or for too long can cause vitamin A to accumulate in the body, which can result in hypervitaminosis A, toxicity, and potentially harmful birth defects.
The recommended daily amount (RDA) for vitamin A is measured in retinol activity equivalents (RAE), which accounts for the different levels of activity of retinol and provitamin A carotenoids. To give you an idea, 1 RAE is equal to 1 microgram of retinol or 3 International units (IU).
Here’s the RDA for vitamin A:
* 700 RAE for adult women
* 900 RAE for adult men
* 750 to 770 RAE for pregnant women
* 1200 to 1300 RAE for women who are breastfeeding
To prevent toxicity, upper intake levels (UL) for vitamin A have been established. For adults, the UL for vitamin A is 3000 RAE per day, which includes preformed vitamin A from food and supplements, and the amount converted from plant-based sources like beta-carotene. It’s worth noting that people in developed countries often consume more preformed vitamin A than the recommended amount, usually from dietary supplements.
Risk Factors and Frequency for Vitamin A Toxicity
Vitamin A toxicity isn’t very common, with less than 10 cases reported each year from 1976 to 1987. Young children and infants are more at risk due to their smaller bodies and lower tolerance to high doses. Typically, acute toxicity occurs when a child accidentally ingests vitamin A supplements.
There’s no significant difference between males and females when it comes to vitamin A toxicity. But, pregnant women need to be careful as high doses of vitamin supplements can pose risks.
Mostly, people in developed countries experience this issue when they take more than the recommended daily amount (RDA) of vitamin A. In areas where vitamin deficiency is a major health issue, supplement programs are in place. However, toxicity can result if people don’t follow the dosing guidelines properly.
- One group at risk of vitamin A toxicity are those that heavily rely on eating liver-based food sources. This is because such foods, like chicken liver or polar bear liver, have high amounts of vitamin A.
- Despite this, only a few instances are reported in medical literature, so it’s not considered a significant health concern.
Signs and Symptoms of Vitamin A Toxicity
When a person consumes too much vitamin A, either through a diet rich in this vitamin, supplements, or oral medications, they may experience a range of symptoms. These can often include problems with vision, headaches, dry skin, loss of hair, feeling tired, and pain in the bones. A doctor might notice certain signs during a physical examination, like:
- Dryness in the eyes and mouth
- Scaly skin
- Hair loss
- Swelling of the optic disc in the eye (papilledema)
- Bone tenderness
- An enlarged liver (hepatomegaly)
In some cases, if a person has been using creams or lotions containing vitamin A, they might show signs of skin peeling and redness in the area where the product was applied. However, they’re not likely to have any of the system-wide symptoms.
Testing for Vitamin A Toxicity
If you keep getting headaches while on vitamin A medication, your doctor may have to check for conditions such as high pressure in your brain or pseudotumor cerebri syndrome.
If your doctor suspects that you have vitamin A toxicity, they might perform laboratory tests, including:
1. Vitamin A levels in your blood: In cases of vitamin A toxicity, blood levels typically exceed 80 mcg/dL.
2. Liver function tests: Your doctor may check your blood for levels of certain substances that may show your liver is damaged or inflamed.
3. Serum lipids: These tests measure the levels of fats in your blood. With vitamin A toxicity, levels of triglycerides and cholesterol usually increase.
4. Blood tests: Other blood tests can reveal problems like leukocytosis (too many white blood cells), thrombocytopenia (too few platelets), and anemia (too few red blood cells).
5. Bone markers: Your doctor might check the levels of a substance called alkaline phosphatase. An increase in this substance is associated with bone turnover.
6. Kidney function test: Elevated levels of blood urea nitrogen and creatinine can suggest kidney problems.
7. Electrolyte imbalances: Your doctor may also look for abnormal levels of sodium, potassium, and calcium in your blood, which can occur in vitamin A toxicity.
Regular monitoring is necessary for some patients. If you are taking isotretinoin, your lipid levels should be checked regularly. Any increase in liver enzymes are usually mild and reversible, but you might also need regular checks for levels of certain liver enzymes.
Women who can become pregnant must have two negative pregnancy tests, done 30 days apart, before starting treatment with isotretinoin. More tests will be needed during and after treatment.
If you are being treated with bexarotene, you should have regular checks of your Free T4 (a thyroid hormone) level, as well as fasting serum lipid levels at the start of treatment and every 1-2 weeks until they stabilize.
For patients with kidney disease taking etretinate, regular kidney function monitoring is necessary throughout treatment.
Treatment Options for Vitamin A Toxicity
If someone has consumed too much vitamin A, the first step to treat them is to stop their intake of vitamin A. It’s also important to manage any symptoms they may be experiencing and take care of their overall health. If someone has applied too much vitamin A cream on their skin, the best way to manage the resulting skin irritation is to reduce the amount and frequency of applications and use more skin moisturizers. They should not worry, as the skin irritation is likely to improve with continual use of the products.
Acute vitamin A toxicity is rare, but if it does occur, recovery usually happens quickly after stopping the vitamin A medications. It’s also crucial to identify any sources of excessive vitamin A intake such as dietary supplements and medications. Until the toxicity is resolved, patients should avoid foods rich in vitamin A like liver and fortified foods.
Supporting patients suffering from vitamin A toxicity involves regularly checking up on the patient’s health. In severe cases, hospital admission might be necessary. Patients with low blood pressure can be treated with fluid administration and those with high levels of calcium in the blood can be managed with the help of hormones like calcitonin and corticosteroids. If there’s damage to the liver, a function test can help assess the degree of damage and guide further treatment decisions.
If the skin becomes dry or starts to peel due to an overdose of vitamin A, using moisturizers can help manage discomfort and promote skin healing. If a person experiences dry eyes, they can use artificial tears or lubricating eye drops, including those that contain a chemical called methylcellulose.
Chronic toxicity caused by medication depends on the specific drug and its side effects. For instance, if oral medication based on vitamin A derivatives increases fasting triglyceride levels to 800 mcg/dL or higher, the options include stopping the medication, lowering the dose, or adding a medication that lowers lipids to prevent inflammation of the pancreas. Lower triglyceride elevation levels can be observed or treated in a similar manner.
Patient suffering from toxicity due to a medicine named bexarotene may need to use certain medications to manage increased blood lipid levels and lower the risk of pancreas inflammation. The therapy may need to be stopped if despite intervention, the blood lipid levels remain high.
If diagnosed with pseudotumor cerebri syndrome (a condition that mimics brain tumor symptoms), patients need to stop using vitamin A medications and may need a drug called acetazolamide to lower their brain pressure.
If a fetus is exposed to vitamin A derivatives, it can result in permanent birth defects known as teratogenic malformations. Based on the affected organ system, the necessary care can differ significantly, involving supportive measures or surgery.
What else can Vitamin A Toxicity be?
When a doctor is trying to diagnose if a person has too much vitamin A (also known as hypervitaminosis A), they need to make sure that the symptoms aren’t caused by other health problems, including:
- Liver problems: This could be due to viral diseases, misuse of alcohol, or adverse reactions to drugs.
- High calcium levels in the blood (hypercalcemia): This could be due to overactive parathyroid glands, cancer, or taking too much calcium and vitamin D.
- Thyroid issues (hypothyroidism): This can be due to problems with the thyroid gland itself or medications.
- Long-term kidney disease (chronic renal failure): This could be due to diabetes, high blood pressure, kidney inflammation (glomerulonephritis), or abnormal sacs filled with fluids in the kidneys (polycystic kidney disease).
- Brain and nervous system problems: Symptoms like headaches, feeling sick and throwing up might not always be due to too much vitamin A, but could be symptoms of a false brain tumor (also known as pseudotumor cerebri).
- Skin conditions: Certain skin conditions could cause skin peeling (exfoliative dermatitis).
- General symptoms: Certain general symptoms like skin rashes, joint aches, tiredness, and kidney and liver abnormalities could indicate other complex conditions such as systemic lupus erythematosus, and not only an excess of vitamin A.
It’s important for the doctor to look carefully at these possibilities and carry out the right tests to find out what’s causing the symptoms.
What to expect with Vitamin A Toxicity
The outlook for hypervitaminosis A, which is when you have too much vitamin A in your system, depends on how bad it is and how long you’ve been exposed to high levels. In most people who stop taking in extra vitamin A, symptoms usually gradually go away and patients can expect a full recovery. Symptoms like dry skin, headaches, and feeling sick typically get better within a few weeks or months without any long-lasting problems.
That said, severe cases can have major consequences. Having too much vitamin A for a long period can cause serious damage to your organs, including your liver, bones, nervous system, and skin. Changes in the liver due to fibrosis or cirrhosis might not be reversible. Bone problems like reduced bone density or fractures might continue even after you stop taking in extra vitamin A. In the case of pseudotumor cerebri, which is a condition that mimics a brain tumor, any problems with vision might be permanent. The outlook largely depends on how much damage has been done to your organs and how quickly you get treatment.
Possible Complications When Diagnosed with Vitamin A Toxicity
Vitamin A toxicity can lead to several complications, as listed below:
- Acute toxicity: This can cause nausea, vomiting, headache, dizziness, irritability, blurry vision, and increased pressure inside your skull.
- Chronic toxicity: Symptoms include dry, itchy skin, hair loss, pain in bones and joints, fatigue, loss of appetite, and weight loss.
- Teratogenic effects: These are harmful effects on a developing fetus that could lead to facial abnormalities, problems with the brain and nervous system, and heart malformations.
- Hepatic toxicity: This could lead to an enlarged liver, high liver enzymes, yellowing of the skin and eyes (jaundice), scarring and hardening of your liver (fibrosis and cirrhosis).
- Skeletal abnormalities: Your bones might get weakened due to increased bone breakdown, decreased new bone formation, osteoporosis, fractures, and bone pain.
- Hematological disturbances: Indicated by changes in blood cells such as increased white blood cells (leukocytosis), a decrease in red blood cells (anemia), and low platelets (thrombocytopenia).
- Central nervous system: Symptoms related to a problem called ‘Pseudotumor cerebri,’ which mimics a brain tumor. Symptoms include headache, visual disturbances, and swelling of the optic nerve (papilledema).
Preventing Vitamin A Toxicity
Teaching patients about the harmful effects of too much vitamin A involves many healthcare professionals, like doctors, nurses, dieticians, pharmacists and others. All of these professionals explain the importance of having a balanced diet with all the essential vitamins and minerals during regular check-ups. They also give guidelines regarding foods that are high in vitamin A, such as liver, fish, dairy products, eggs, and colorful fruits and vegetables. Patients are also informed about the daily amount of vitamin A they should take, which depends on factors like their age, gender, and overall health.
Pharmacists give information about prescription and non-prescription drugs that contain vitamin A or similar compounds, including retinoids. They explain how to use these medications correctly and warn about possible side effects if not used as recommended. They highlight the importance of not exceeding the suggested dose and duration of treatment.
Doctors and other healthcare professionals who care for women who can potentially get pregnant, have a responsibility to teach them about the possible risks of taking too much vitamin A from supplements or medications during pregnancy because it can harm the baby.
If a healthcare provider suspects a patient might have vitamin A toxicity, they should explain the potential complications to the patient and advise them to stop taking extras vitamin A. This could mean the patient needs to change their diet or adjust any medications or supplements they’re taking.
