What is the relationship between hypothyroidism and vitamin D deficiency?

From the Guidelines

Relationship Between Hypothyroidism and Vitamin D Deficiency

Hypothyroidism is often associated with vitamin D deficiency, which can exacerbate hypothyroid symptoms, and thus, monitoring and maintaining normal vitamin D levels is crucial for individuals with hypothyroidism 1.

• Vitamin D Supplementation: Daily vitamin D supplementation is recommended, sometimes with calcium supplementation, to prevent deficiency and related complications 1.
• Thyroid Disease and Vitamin D: Thyroid disease, including hypothyroidism, is common in adults, and symptoms may be confused with those of other conditions, emphasizing the need for regular thyroid function assessment, including annual checks 1.
• Management Considerations: Standard treatments for hypothyroidism are effective, but predisposition to other conditions like obesity and type 2 diabetes should be considered, and preventive measures implemented early on 1.
• Importance of Monitoring: Regular monitoring of calcium, parathyroid hormone, magnesium, thyroid-stimulating hormone, and creatinine concentrations is essential, along with targeted calcium monitoring at vulnerable times, such as during pregnancy or acute illness 1.
• Potential Interactions: While the direct interaction between vitamin D supplementation and levothyroxine absorption is not explicitly mentioned in the provided evidence, it is crucial for patients to follow healthcare provider recommendations to minimize potential interactions and ensure effective management of hypothyroidism.
• Individualized Treatment: Patients with hypothyroidism should consult their healthcare provider to determine the best course of treatment, including vitamin D supplementation and monitoring, based on their individual needs and health status.

From the Research

Relationship Between Hypothyroidism and Vitamin D Deficiency

• The relationship between hypothyroidism and vitamin D deficiency has been investigated in several studies 2, 3, 4, 5, 6.
• A study published in 2013 found that patients with hypothyroidism had significantly lower serum vitamin D levels than healthy controls, and that vitamin D deficiency was associated with hypocalcemia and the severity of hypothyroidism 2.
• Another study published in 2015 found that subclinical hypothyroidism in combination with vitamin D deficiency increased the risk of impaired left ventricular diastolic function 3.
• A study published in 2020 found that vitamin D deficiency was associated with autoimmune hypothyroidism, and that there was a negative correlation between vitamin D levels and anti-thyroid peroxidase antibodies in patients with autoimmune hypothyroidism 4.
• A pilot randomized clinical trial published in 2020 found that vitamin D replacement therapy significantly decreased serum TSH levels in patients with subclinical hypothyroidism and vitamin D deficiency 5.
• A large population-based study published in 2021 found that low vitamin D levels were associated with an increased risk of hypothyroidism, and that vitamin D deficiency was more common among hypothyroid patients than among normal controls 6.

Key Findings

• Vitamin D deficiency is common among patients with hypothyroidism 2, 3, 4, 5, 6.
• Vitamin D deficiency is associated with hypocalcemia and the severity of hypothyroidism 2.
• Subclinical hypothyroidism in combination with vitamin D deficiency increases the risk of impaired left ventricular diastolic function 3.
• Vitamin D replacement therapy may be beneficial for patients with subclinical hypothyroidism and vitamin D deficiency 5.
• Low vitamin D levels are associated with an increased risk of hypothyroidism 6.