Association Between Vitamin D and the Development of Uterine Fibroids
Phase: NA
Conditions: Gynaecological Disease, Vitamin D Deficiency
Sponsor: Second Affiliated Hospital of Wenzhou Medical University

 
 
 
 
 
Association between Vitamin D 
and The Development of Uterine 
Fibroids 
 
 
 
 
 
2018.3.15 

Study objectives The primary objective of this part is to assess the efficacy of 
supplementation with vitamin D on inhibiting the development of uterine fibroids in 
one year and two years. The secondary objective of this study is to evaluate the safety 
of supplementation with vitamin D in subjects. 
Trial design This is an open-label, randomised controlled trial. After signing of 
informed consent, patients with vitamin D deficiency (12 ng/ml ≤ Serum 
25-hydroxyvitamin D3 < 20 ng/ml) and uterine fibroids will be randomly assigned in a 
1:1 ratio to intervention group A or control group B. Intervention group A will accept 
an oral dose of 1600 IU/day vitamin D3 for up to 2 years. Control group B will receive 
2 years follow-up. Patients with vitamin D insufficiency (20 ng/ml ≤ Serum 
25-hydroxyvitamin D3 < 30 ng/ml) and uterine fibroids will be randomly assigned in a 
1:1 ratio to intervention group C or control group D. Intervention group C will accept 
an oral dose of 800 IU/day vitamin D3 for up to 2 years. Control group D will receive 
2 years follow-up. Gynecologic ultrasound examinations will be performed every 
three months. The mount, location and size of the uterine fibroids will be documented 
(the transverse, longitudinal, and antero-posterior diameters of fibroids will be 
documented at each efficacy ultrasound examination for volume calculation). Percent 
change in volume of the total fibroids compared to baseline in different 
groups(baseline = last value obtained before randomization). Three perpendicular 
diameters (d1, d2, and d3) were collected for each fibroid, and the volume of each 
fibroid (in cm3) was calculated with the ellipsoid formula: 4/3∗π∗(d1∗d2∗d3)/8. For 
each patient, the total volume of fibroids (defined as the sum of the volumes of all the 
fibroids detected) was also calculated. The safety of vitamin D in subjects with uterine 
fibroids will be evaluated, including blood routine examination, electrolyte, hepatic 
and renal function, liver and urinary system ultrasound, and serum 25-hydroxyvitamin 
D3. Vitamin D3 Drops are purchased from Sinopharm star shark pharmaceutical 
(xiamen) co., LTD. An overview of the study design is shown in Figure 2 and Table 2. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Entrollment 
Exclusion 
Intervention 
group C 
Control 
group B 
Intervention 
group A 
Two years follow-up 
Outcomes assessment at 12 and 24 months 
Vitamin D deficiency 
Vitamin D insufficiency 
Control 
group D 

 
 
 
 
Figure 2 flow diagram. 
 
Table 2:time of date collection 
 
 
 
 
 
 
 
 
 
Follow-up 
1 
2 
3 
4 
5 
6 
7 
8 
9 
Months 
0 
3 
6 
9 
12 
15 
18 
21 
24 
The form of follow-up 
Out-patient 
Informed consent 
x 
 
 
 
 
 
 
 
 
Medical history 
x 
 
 
 
 
 
 
 
 
Physical examination 
x 
 
 
 
 
 
 
 
 
Serum 25-hydroxyvitamin D3 
x 
x 
x 
x 
x 
x 
x 
x 
x 
Urine pregnancy test 
x 
x 
x 
x 
x 
x 
x 
x 
x 
Gynecologic ultrasound 
x 
x 
x 
x 
x 
x 
x 
x 
x 
Hepatic and renal function 
x 
 
x 
 
x 
 
x 
 
x 
Electrolyte 
x 
 
x 
 
x 
 
x 
 
x 
Blood routine examination 
x 
 
x 
 
x 
 
x 
 
x 
Liver and urinary  
System ultrasound 
x 
 
 
 
x 
 
 
 
x 
Side-effect assessment 
 
x 
x 
x 
x 
x 
x 
x 
x 
Changes in menstruation 
 
x 
x 
x 
x 
x 
x 
x 
x 
Adverse event assessment 
 
x 
x 
x 
x 
x 
x 
x 
x 
Vitamin D receptor genotype 
x 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Sample size According to a previous study, the volume of uterine fibroids was 8.2 
(2.1-30.5) cm3 after the supplement of vitamin D 12 months and 11.4 (5.5-22.3) cm3 
in the control group, respectively. On the basis of a 0.9 power to detect a significant 
difference (α=0.05, one-sided), 320 participants will be required for the four groups 
and in a 1:1:1:1 ratio. Allowing for a 10% withdrawal rate, we plan to include 360 
patients in the whole trial. 
 Inclusion criteria 
1. Patients are willing to cooperate with the follow-up and sign informed consent; 
2. Females aged 35-50 who are diagnosed as having uterine fibroids by transvaginal 
or abdominal ultrasonography; 
3. The maximum average diameter of intramural myoma is ≤ 4cm，≥ 1cm; The 
amount of myoma is less than 4; 
4. Serum 25-hydroxyvitamin D3 < 30 ng/ml, ≥ 12 ng/ml. 
Exclusion criteria 
1. Patients with heavy menstrual bleeding (>80.0 mL), menstrual disorders, pelvic 
discomfort, infertility, or other indications for operation; 
Statistical analysis 

2. Patients complicated with myoma degeneration and adenomyosis that were 
suspected or diagnosed by ultrasound or gynecologic examination; 
3. Allergic to vitamin D3; 
4. Use of sexual hormone, mifepristone, gonadotropin-releasing hormone agonist 
(GnRHa), or other medication which is likely to interfere with uterine fibroids within 
3 months; 
5. Pregnancy, lactation, postmenopause, or planned pregnancy within two years; 
6. Suspected or identified as other tumors of genital tract; 
7. History of osteoporosis or vitamin D deficiency taking vitamin D supplements 
within previous one month; 
8. History of autoimmune diseases, infectious diseases (tuberculosis, AIDS), 
autoimmune diseases, digestive system diseases (malabsorption, crohn disease, and 
dysentery); 
9. Alanine aminotransferase (ALT) or aspartate transaminase(AST) more than 3 times 
of the normal upper limit, total bilirubin (TBIL) more than 2 times of the normal 
upper limit; 
10. Creatinine levels≥1.4 mg/dL (123μmol/L) or creatinine clearance ≤ 50 mL/min; 
11. History of malignant tumors; 
12. Simultaneous participation in another clinical study with investigational medicinal 
product(s) or researcher thinks the subjects are not suitable for this trial. 
Outcomes measures Primary outcomes: percent change in volume of the largest 
fibroid and total fibroids compared to baseline (baseline = last value obtained before 
randomization; measured by ultrasound examination). Secondary outcomes: 
percentage of subjects undergoing other medical or surgical treatment, hypercalcemia, 
urinary calculus, abnormal liver and renal function. Ultrasound examinations will be 
performed by a physician well experienced in gynecology. If possible, the same 
examiner should conduct all examinations of a subject throughout the study and the 
same ultrasound machine (per site) should be used throughout the study. For each 
subject, the most appropriate ultrasound method (transvaginal or abdominal) should 
be used depending on fibroids location and this method should be used consistently 
throughout the study. 
Withdrawal Subjects must be withdrawn from the study when one of the following 
criteria occurs: 
1. At their own request. At any time during the study and without giving reasons, a 
subject may decline to participate further. The subject will not suffer any 
disadvantages as a result; 
2. In the investigator's opinion, continuation of the study treatment would be harmful 
to the subject's health; 
3. Obvious non-compliance; 
4. Lost to follow-up; 
5. Pregnancy; 
6. Other medical or surgical treatments of uterine fibroids. 
7. Receive other medical treatments which may affect the level of serum 
25-hydroxyvitamin D3 or other surgical treatments. 

8. The level of serum calcium > 3.5 mmol/L or serum 25-hydroxyvitamin D3 > 100 
ng/mL. 
Safety assessments Safety will be assessed by renal and liver function test, 
electrolyte, routine blood test, and serum 25-hydroxyvitamin D3. Urine pregnancy test 
and serum 25-hydroxyvitamin D3 level will be detected every three months. Other 
indicators are detected during the period of screening and after the treatment of every 
six months. Liver and urinary system ultrasound will be conducted after the treatment 
of 12 months and 24 months. The occurrence of any adverse events in trial 
participants will be recorded in the case report forms during each patient visit. We will 
withdraw patients who have severe adverse events, as it is unsafe for them to continue 
the trial. Meanwhile, we will give them relevant medical care and follow them up 
until the reaction has terminated. 
Statistical analysis Statistical analyses will be performed using SPSS version 22.0 for 
Windows (SPSS Inc., Chicago, IL, USA). The randomisation sequence is generated 
by the use of the SPSS software. The normality of distribution of continuous variables 
aretested by one-sample Kolmogorov-Smirnov test. Continuous variables with normal 
distribution are reported as mean (standard deviation); non-normal variables are 
presented as median (interquartile range). Means of 2 and 3 or more continuous 
normally distributed variables, respectively, are compared by independent samples 
Student’s t test or one-way ANOVA test. Mann-Whitney U test and Kruskal-Wallistest 
are used, respectively, to compare means of 2 and 3 or more groups of variables not 
normally distributed. The frequencies of categorical variables are compared using 
Pearson χ2 or Fisher’s exact test, when appropriate. A value of P<0.05 is considered 
significant.