Table 2.
Effect of vitamin D supplementation on selected parameters in patients with Hashimoto’s thyroiditis—recent clinical studies.
| Study | Study Population | Dose/Form/Supplementation Time | Evaluated Diagnostic Parameters | Key Results | Ref. |
|---|---|---|---|---|---|
| Clinical trial | 218 euthyroid HT patients | 186 HT patients with 25(OH)D < 30 ng/mL received 1200–4000 IU vitamin D daily for four months | Anthropometric characteristics, SBP, DBP, serum concentrations of vitamin D, TSH, fT4, calcium, phosphorus, titers of TPOAb and TgAb |
- significant negative correlation between 25(OH)D and TPOAb levels among all HT patients; - TPOAb levels were significantly higher in vitamin D deficient HT patients compared to no vitamin D deficiency; - supplementation of vitamin D in vitamin D deficient HT patients caused a significant decrease (20.3%) in serum TPOAb levels; - after supplementation BMI, serum TgAb and TSH levels decreased not significant. |
[27] |
| 75 patients with HT and 43 healthy individuals | Vitamin D deficient patients (<20 ng/mL): 50,000 IU of 25(OH)D3 weekly for eight weeks | Serum levels of vitamin D, TSH, HDL cholesterol and thyroid autoantibodies titers | - patients with HT had significantly lower vitamin D level compared to controls; - titers of thyroid autoantibodies significantly decreased after vitamin D supplementation in euthyroid HT patients; - after supplementation HDL cholesterol level improved in the euthyroid HT group. |
[119] | |
| Prospective study | 82 patients with AIT and vitamin D deficiency (<20 ng/mL) |
Study group (n = 46): patients treated with 1000 IU/day vitamin D for one month; Control group (n = 36): patients without vitamin D therapy |
Serum levels of vitamin D, TSH, fT4, titers of TPOAb and TgAb | - TPOAb and TgAb levels were significantly decreased in the study group, this evaluated parameters did not significantly change in the control group; - thyroid function tests did not significantly change in two groups. |
[120] |
| Randomized controlled trial | 100 newly diagnosed AIT patients |
Study group (n = 50): 60,000 IU 25(OH)D weekly and 500 mg/day calcium for eight weeks; Control group (n = 50): 500 mg/day calcium for eight weeks |
Serum levels of vitamin D and titers of TPOAb | - 74% of HT patients were vitamin D deficient; - significant decrease of TPOAb level in the study group compared to the control group. |
[121] |
| Retrospective study | 198 euthyroid subjects with vitamin D deficiency (<30 ng/mL) |
Study group (n = 95): patients with AIT; Control group (n = 103): subjects without AIT. The groups were also divided into subgroups depending on the dose and period of supplementation |
Serum levels of vitamin D and TSH | - in the study group TSH level significantly decreased after 100,000 IU vitamin D monthly; - no significant changes in TSH level in the control group, regardless of treatment dose and duration; - 25(OH)D level significantly improved with all monthly doses and especially in the group receiving 100,000 IU/month. |
[122] |
| Clinical Trial | 34 euthyroid or mild subclinical hypothyroid HT women with 25(OH)D levels >30 ng/mL, treated ≥6 months with LT4 |
Study group (n = 18): women with LT4 and 2000 IU vitamin D daily for six months; Control group (n = 16): women with LT4 treatment |
Serum levels of vitamin D, TSH, fT4, fT3, titers of TPOAb and TgAb | - in the study group 25(OH)D levels increased, TPOAb titers reduced and tended to reduce TgAb; - vitamin D supplementation did not affect serum levels of TSH, fT3 and fT4; - 25(OH)D level inversely correlated with titers of thyroid antibodies. |
[123] |
| Randomized clinical trial | 42 women with HT |
Study group: 50,000 IU vitamin D weekly for three months; Control group: placebo for three months |
Serum levels of vitamin D, Ca2+ ion, T4, T3, TSH titers of TPOAb and TgAb | - significant decrease of TgAb and TSH levels in the study group; - no significant reduction of TPOAb level in the study group compared to controls; - no significant changes in the serum levels of T3 and T4 levels in both groups. |
[125] |
| Double-blind, randomized, placebo-controlled clinical trial | 56 patients with HT and vitamin D deficiency (≤20 ng/mL) |
Study group (n = 30): 50,000 IU vitamin D weekly for 12 weeks; Control group (n = 26): placebo for 12 weeks |
Serum levels of vitamin D, TSH, calcium, parathormone, creatinine and TPOAb titers | - vitamin D level increased in the study group; - TPOAb and TSH levels did not significantly change in both groups; - significant decrease for PTH level in study group. |
[126] |
| Double-blind, randomized, placebo-controlled clinical trial | 65 vitamin D deficient euthyroid or hypothyroid patients with positive TPOAb |
Study group (n = 33): 50,000 IU vitamin D3 weekly for 12 weeks; Control group (n = 32): placebo for 12 weeks |
Serum levels of calcium, hsCRP, insulin, albumin, phosphorus, TG, TC and HDL cholesterol, IFG, glycated hemoglobin (HbA1c), blood urea nitrogen, creatinine | - levels of vitamin D increased significantly in study group; - HbA1c and insulin levels was increased significantly in both groups; - other variables did not change a significantly after trial. |
[127] |
| A Randomized Open-label Trial | 23 patients with HT | Weekly supplementation of 60,000 IU vitamin D for eight weeks followed by once a month for four months | Serum levels of vitamin D, TSH, fT4, and TPOAb titers | - serum vitamin D level was increased significantly after trial (87% patients had normal levels); - significant increase in the TPOAb and fT4 levels and significant reduction of TSH level after six months of therapy. |
[128] |
| Comparative Study | 47 euthyroid women with HT and low vitamin D status |
Study group (n = 23): 200 μg selenomethionine daily for at least 12 months before the study and 4000 IU vitamin D daily for six months Control group (n = 24): 4000 IU vitamin D daily for six months |
Serum levels of TSH, fT4, fT3, vitamin D, titers of TPOAb and TgAb | - in both groups, 25(OH)D levels were increased, TPOAb and TgAb titers were reduced; - the effects on antibody titers were more pronounced in women receiving vitamin D and selenomethionine; |
[129] |
HT—Hashimoto’s thyroiditis; n—Number of participants; LT4—Levothyroxine; TPOAb—Anti-thyroid peroxidase antibodies; TgAb—Anti-thyroglobulin antibodies; TSH–Thyrotropin; fT4—Free thyroxine; fT3—Free triiodothyronine; 25(OH)D—25-hydroxyvitamin D; IU—International unit; hsCRP, TC—Total cholesterol; TG—Triglycerides; HDL—High-density lipoprotein; IFG—Impaired fasting glycaemia; HbA1c—Glycated hemoglobin; SBP—Systolic blood pressure; DBP—Diastolic blood pressure.