Can toxic levels of Vitamin D (Vit D) cause liver damage?

From the Guidelines

Toxic levels of vitamin D can indeed damage the liver, and it is essential to monitor and manage vitamin D levels to prevent such damage. Vitamin D toxicity, also known as hypervitaminosis D, typically occurs from excessive supplementation rather than from diet or sun exposure. When vitamin D levels become too high (generally above 150 ng/mL), calcium absorption increases dramatically, leading to hypercalcemia. This excess calcium can deposit in various organs, including the liver, causing inflammation and potential liver damage. The liver is particularly vulnerable because it plays a key role in vitamin D metabolism. Symptoms of vitamin D toxicity affecting the liver may include abdominal pain, nausea, vomiting, and in severe cases, elevated liver enzymes indicating hepatocellular injury.

According to the most recent and highest quality study, it is advisable to assess plasma vitamin 25 hydroxy-D (25OHD) levels in all patients with chronic liver disease, particularly in those with advanced disease 1. Although there are no specific recommendations in patients with chronic liver disease except for those with chronic cholestasis, it seems reasonable to supplement all chronic liver disease patients with vitamin D levels below 20 ng/ml with oral vitamin D until reaching a serum vitamin D level above 30 ng/ml. Higher doses may be necessary in patients with non-alcoholic fatty liver disease.

To avoid vitamin D toxicity, adults should generally not exceed 4,000 IU daily without medical supervision. If you're taking vitamin D supplements, regular blood monitoring of both vitamin D and calcium levels is advisable, especially at higher doses. Treatment for vitamin D toxicity involves stopping supplementation, increasing fluid intake, possibly using corticosteroids, and in severe cases, hospitalization for intravenous fluids and medications to lower calcium levels.

Some key points to consider:

• Vitamin D toxicity can cause hypercalcemia, hyperphosphatemia, suppressed parathyroid hormone, and hypercalciuria.
• The 25-(OH)D level associated with toxicity is often defined as >500 nmol/L [>200 ng/mL] 1.
• Treatment with vitamin D plus calcium may also be associated with increased risk for kidney stones; vitamin D alone does not seem to increase this risk.
• In general, treatment with oral vitamin D does not seem to be associated with serious harms.
• Treatment with increased sun exposure (specifically ultraviolet B [UVB] radiation) may increase risk for skin cancer.
• Because of this concern, increased sun exposure is generally not recommended as treatment of vitamin D deficiency.

Overall, it is crucial to prioritize morbidity, mortality, and quality of life when managing vitamin D levels and to be aware of the potential risks and benefits of vitamin D supplementation.

From the Research

Vitamin D Toxicity and Liver Damage

• There is no direct evidence to suggest that toxic levels of vitamin D can damage the liver 2, 3, 4, 5, 6.
• However, vitamin D toxicity can lead to hypercalcemia, which can cause a range of symptoms including nausea, vomiting, dehydration, confusion, and coma 2, 3, 6.
• Hypercalcemia can also lead to kidney damage and other complications, but the direct impact on the liver is not well established 2, 3.
• Some studies suggest that vitamin D may play a role in liver homeostasis and disease, but the evidence is limited and further research is needed to fully understand the relationship between vitamin D and liver health 4, 5.

Mechanisms of Vitamin D Toxicity

• Vitamin D toxicity can occur due to excessive intake of vitamin D supplements, malfunctions of the vitamin D metabolic pathway, or the existence of coincident disease that produces the active vitamin D metabolite locally 3.
• Serum 25-hydroxyvitamin D concentrations higher than 150 ng/ml (375 nmol/l) are the hallmark of vitamin D toxicity due to vitamin D overdosing 3.
• The pathophysiology of hypercalcemia from vitamin D intoxication results from the long-term effects of vitamin D storage in adipose tissue 6.

Treatment of Vitamin D Toxicity

• Treatment of vitamin D toxicity typically involves hydration, intravenous bisphosphonates, and glucocorticoids 2, 3, 6.
• In some cases, treatment with calcitonin and intravenous fluids may also be necessary 6.
• It is essential to identify and treat the underlying cause of vitamin D toxicity to prevent long-term complications 2, 3.