The Effect of Bariatric Surgery on Subclinical Hypothyroidism Patients in Shiraz

Abstract

Background:

Previous studies have shown that people with hypothyroidism improved after sleeve gastrectomy. This study was conducted on subclinical hypothyroid patients who had undergone bariatric surgery and were examined in terms of thyroid hormone changes in Shiraz.

Methods and Patients:

In this study, 20 obese subclinical hypothyroid patients who had undergone laparoscopic sleeve gastrectomy and gastric bypass surgery at Mother and Child Hospital and Shahid Faqihi Hospital were carefully examined.

Results:

The mean of weight before and 6 months after surgery was117.54 ± 6.81 (kg) and 88.39 ± 5.27 (kg), respectively (p = 0.003). The thyroid-stimulating hormone (TSH) levels were significantly decreased 6 months after the surgery (p = 0.005), but T3 and T4 levels were not changed 6 months after the surgery.

Conclusion:

The use of bariatric surgery in patients with hypothyroidism causes improvement after the operation. It has a decreasing effect on TSH levels in hypothyroid subclinical obese patients after surgery. Biochemical factors such as blood sugar and liver enzymes were compared between before and 6 months after surgery, and it was indicated that they their metabolic syndrome improved after surgery.

Introduction

Obesity is the cause of many diseases, among which the diseases of increased hyperlipidemia and metabolic diseases such as diabetes, fatty liver, atherosclerosis, and various cancers, as well as mental illnesses, can be mentioned. According to previous studies, it is claimed that reducing the weight of patients can reduce the risk of heart diseases, diabetes, infertility, and even cancer.^1–8 Normally, bariatric surgery is performed for individuals with a body mass index (BMI) >35 or those with an underlying disease.

Previous studies have shown that people with hypothyroidism improve after sleeve gastrectomy.⁸ This means that the effect of bariatric surgery on improving thyroid function is caused by mechanisms other than weight loss, possibly hormonal. The effects of weight loss on thyroid-stimulating hormone (TSH) level changes were investigated in a previous study.⁹ Subclinical hypothyroidism is a disorder often caused by autoimmune (Hashimoto) thyroiditis in ∼4–10% of the adult population characterized by an elevated serum TSH level with normal levels of T4.¹⁰ However, serum TSH level rises in individuals older than 70 years without thyroid disease. Subclinical hypothyroidism might be associated with an increased risk of cardiovascular disease and mood disorders.¹⁰ In most of patients with subclinical hypothyroidism, there is no treatment.¹⁰ Subclinical hypothyroidism might be associated with metabolic diseases such as hypertension, hyperglycemia, and dyslipidemia.¹¹

In the present study, the serum levels of all three hormones were measured before and 6 months after the operation. This study aimed to investigate the relationship between the amount of weight loss after bariatric surgery and thyroid hormones in obese subclinical hypothyroid patients in Shiraz as the primary outcome. Investigating other biochemical factors such as blood sugar, lipid profile, parathyroid hormone, and liver enzymes in subclinical hypothyroid patients undergoing surgery and comparing with before surgery was the other aim of this study as the secondary outcome.

Methods

The study was approved by the ethics committee of Shiraz University of Medical Sciences, with the code number of IR.SUMS.REC.1400.666.

Patients

The laboratory tests of sugar, blood lipids and pressure, and thyroid hormones of the participants were done before and 6 months after the operation. The study was a case–control study, and the effect of surgery on the hormonal changes of each person was considered.

Inclusion criteria: All subclinical hypothyroid obese people whose TSH level was between 5 and 10 mIU/L with normal T4 and had undergone surgery.

Exclusion criteria: Patients with hypothyroidism or their hyperthyroidism were removed because the hormone levels before and after the operation were compared. Also, the patients who had undergone thyroidectomy were excluded from the study. Weight, BMI, parathyroid hormone, glucose and lipid profile, and liver enzymes of patients were measured before and after the surgery.

Statistical analysis

Quantitative changes before and after the surgery were compared with paired t-test or Wilcoxon, and SPSS (version 23) was used for statistical analysis. Spearman test was used for correlation analysis. A p value of <0.05 was considered significant. Mean data ± standard deviation (SD) was used for comparison.

Results

The participants’ mean age was 39.08 ± 9.94 years (SD), with a range of 19 to 56 years. About 83.3% were females and 16.7% were males. The mean weight before and after the surgery was 117.54 ± 6.81 (kg) and 88.39 ± 5.27 (kg), respectively (p = 0.003). The TSH levels were significantly decreased after the surgery (p = 0.005), but T3 and T4 did not change after it (Table 1).

Table 1.

Laboratory Data of Patients Before and After the Surgery (n = 20)

Parameters	Before surgery (mean ± SD)	After surgery (mean ± SD)	p value
BMI (kg/m²)	43.93 ± 5.26	33.58 ± 6.38	0.003
HbAIC (%)	5.77 ± 0.63	4.90 ± 0.20	0.109
TSH (mIU/L)	7.65 ± 1.73	4.37 ± 1.92	0.005
T3 (µg/dL)	1.47 ± 0.33	1.40 ± 0.38	0.507
T4 (µg/dL)	8.05 ± 1.83	8.09 ± 1.85	0.508
FBS (mg/dL)	97.82 ± 19.87	91.18 ± 8.06	0.180
TG (mg/dL)	126.64 ± 47.24	85.18 ± 18.29	0.037
Chol (mg/dL)	180.91 ± 40.18	176.73 ± 32.66	0.594
HDL (mg/dL)	48.18 ± 12.62	58.36 ± 7.50	0.036
LDL (mg/dL)	120.54 ± 35.93	102.18 ± 32.65	0.074
AST (U/L)	25.88 ± 13.19	21.18 ± 10.39	0.102
ALT (U/L)	27.64 ± 14.74	10.18 ± 13.30	0.003
AlKph (U/L)	173.87 ± 43.94	67.71 ± 72.20	0.012
vitD3 (ng/mL)	17.15 ± 8.86	33.88 ± 19.59	0.021
Ca (mg/dL)	9.38 ± 0.50	9.37 ± 0.42	0.526
Phosphorus (mg/dL)	2.97 ± 0.58	3.42 ± 0.41	0.465
PTH (pg/mL)	44.73 ± 11.07	40.36 ± 13.63	0.314

Wilcoxon test was used for these data analysis.

BMI, body mass index; TSH, thyroid-stimulating hormone.

The mean of weight loss was 29.15 ± 11.88 (kg), and the difference between the two type of surgery was not significant (p = 806). No correlation was found between the improvement of TSH level and the percentage of excess weight loss (r = 0.347, p = 0.327) as the primary outcome. We excluded the patients who were using levothyroxine products and had a history of hypothyroidism. The changes in lipid and glucose profiles of patients and liver enzymes are shown in Table 1 as secondary outcome.

Discussion

Accordance to our results, some previous studies have claimed that the use of bariatric surgery is useful in treating hypothyroidism in 90 patients, and 40 patients had impaired TSH levels before the operation, and they recovered significantly after the surgery.⁹ Also, there were no correlations between the improvement in the TSH level and percentage of excess weight loss. So far, there has been no report on the use of bariatric surgery as a treatment in these people.⁹ In another study on patients who had undergone sleeve surgery, it was observed that the symptoms of hypothyroidism improved significantly after the surgery.¹² In that study, before surgery, 30 people (23.4%) had subclinical hypothyroidism. The prevalence of subclinical hypothyroidism decreased significantly and reached 7.8 at the end of the follow-up (p < 0.001); none of the patients had new hypothyroidism at the end of the follow-up, which is in the same line with our study.¹²

The levels of TSH after the operation showed a statistically significant change compared with preoperative levels (p = 0.005), but T3 and T4 showed no change after the surgery in our results. All three of these hormones decreased postoperatively in the study conducted by Reinehr et al. in 2006. They investigated the children who had experienced severe weight loss.¹³ The results of other studies, such as those conducted by Chikunguwo et al. in 2007, Nyrnes et al. in 2006, and Iacobellis et al. in 2005, about a reduction in TSH hormone after bariatric surgeries, were consistent with those of the present study. However, these studies reported postoperative levels of T4 without any changes.^14–16 Triglyceride, HDL, ALT, ALK phosphatase, and vitD3 levels were the significant changes, as shown in Table 1. Like our previous studies,^17,18 the metabolic parameters improved after the surgery. The use of bariatric surgery in patients with hypothyroidism caused improvement after the operation.

Conclusion

Bariatric surgery has a significant effect on thyroid hormones (decrease of TSH level) in hypothyroid subclinical obese patients after surgery. Biochemical factors such as blood sugar and liver enzymes were compared between before and 6 months after the surgery and could be indicated as the improvement of metabolic syndrome after surgery. Moreover, the use of bariatric surgery could be suggested in patients with subclinical hypothyroidism.

Footnotes

Authors’ Contributions

All authors contributed to the conception of the work, conducted the study, revised the draft, approved the final version of the article, and agreed with all aspects of the work.

Author Disclosure Statement

The authors have no conflicts of interest to declare.

Funding Information

The authors declared that this study has received no financial support.

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