Subclinical hypothyroidism, outcomes and management guidelines: a narrative review and update of recent literature

Levothyroxine for subclinical hypothyroidism during pregnancy: an updated systematic review and meta-analysis of randomized controlled trials

PURPOSE

We aimed to perform a systematic review and meta-analysis addressing the efficacy of levothyroxine therapy in pregnant women with subclinical hypothyroidism considering most recent evidence and subgroups of interest for clinical practice.

METHODS

PubMed, Embase, and Cochrane Central were searched from inception for randomized controlled trials (RCTs) comparing levothyroxine with placebo or no intervention in pregnant women with subclinical hypothyroidism. We used a random-effects model and conducted subgroup analyses based on thyroid peroxidase antibody status, thyroid stimulating hormone levels, fertility treatment, and recurrent miscarriage.

RESULTS

We included 11 RCTs comprising 2,749 pregnant women with subclinical hypothyroidism. Patients treated with levothyroxine (1,439; 52.3%) had significantly lower risk of pregnancy loss (risk ratio 0.69; 95% confidence interval 0.52-0.91; p < 0.01; 6 studies). However, there was no significant association between levothyroxine and live birth (risk ratio 1.01; 95% confidence interval 0.99-1.03; p = 0.29; 8 studies). No statistically significant interaction was observed across subgroups (p > 0.05).

CONCLUSION

Levothyroxine replacement therapy for subclinical hypothyroidism during pregnancy may decrease pregnancy loss when early prescribed. Nevertheless, further investigation is needed in patients with thyroid stimulating hormone above four milliunits per liter, especially when associated with recurrent miscarriage or infertility.

The Relationship between Subclinical Hypothyroidism and Carotid Intima-Media Thickness as a Potential Marker of Cardiovascular Risk: A Systematic Review and a Meta-Analysis

BACKGROUND AND OBJECTIVES

Thyroid dysfunction is known to have significant consequences on the cardiovascular system. The correlation between carotid intima-media thickness (CIMT) and subclinical hypothyroidism (SCH) has been frequently evaluated in clinical studies in recent years. This study aimed to evaluate the significance of this association through a meta-analysis.

METHODS

We conducted a systematic search of PubMed, MedLine, Scopus, and Web of Science databases using the keywords 'subclinical hypothyroidism and carotid intima-media thickness', from the beginning of each database until January 2023. We established the inclusion and exclusion criteria and considered studies that met the inclusion criteria. We used Jamovi for statistical analysis of the data.

RESULTS

We identified 39 observational studies that met the inclusion criteria, with 3430 subjects: 1545 SCH and 1885 EU. Compared to euthyroid subjects (EU), subjects with subclinical hypothyroidism (SCH) had significantly increased carotid intima-media thickness (CIMT) values; the estimated average mean difference was 0.08 (95% CI 0.05 to 0.10), p < 0.01, I2 = 93.82%. After the sensitivity analysis, a total of 19 from the 39 abovementioned studies were analyzed, with most studies showing a positive association between SCH and thickening of the carotid wall; the estimated average mean difference was 0.04 (95% CI 0.02 to 0.07), p = 0.03, I2 = 77.7. In addition, female sex, advanced age, and high cholesterol levels statistically significantly influenced this association.

CONCLUSIONS

Our meta-analysis indicates a significant positive association between SCH and increased CIMT, but with some limitations.

The Effects of Patient Characteristics on the Management of Subclinical Hypothyroidism: A Survey of Faculty and Trainees

OBJECTIVE

There is no universal approach to the management of subclinical hypothyroidism (SCH). This study was designed to determine the impact of patient characteristics on management decisions in SCH amongst physician faculty members and trainees.

METHODS

An online survey was distributed to faculty members and medical trainees (ie, interns, residents, and fellows) at multiple academic medical centers. The survey included 9 clinical scenarios describing women with SCH with 5 management options sequenced from most "conservative" (no further treatment or monitoring) to most "aggressive" (treatment with levothyroxine).

RESULTS

Of the 194 survey respondents, 95 (49.0%) were faculty members and 99 (51.0%) were trainees. Faculty members were more likely to report being "confident" or "very confident" in making the diagnosis of SCH compared to trainees (95.8% vs 46.5%, P < .001). Faculty members were also more likely to consider patient preference for treatment (60.0% vs 32.3%, P < .001). Among all respondents, the clinical factors that resulted in the highest predicted probability of treatment were hypothyroid symptoms (predicted probability [PP] 68.8%, 95% CI [65.7%-71.9%]), thyroid stimulating hormone >10 mIU/L in a 31-year-old (PP 63.9%, 95% CI [60.3%-67.3%]), and the desire for fertility (PP 52.2%, 95% CI [48.6%-56.0%]). In general, faculty members favored more aggressive treatment across all clinical scenarios.

CONCLUSION

The presence of symptoms, thyroid stimulating hormone >10 mIU/L, and desire for fertility were most predictive of the decision to treat in SCH. In several clinical scenarios, both trainee and faculty decision-making demonstrated discordance with general SCH management principles.

IMMUNOLOGICAL DISORDERS AND COLON DYSBIOSIS IN OBESE PATIENTS WITH HYPOTHYROIDISM

OBJECTIVE

The aim: To investigate the peculiarities of immunological changes and their relationship with colon dysbiosis in obese patients with HT.

PATIENTS AND METHODS

Materials and methods: The examined patients included 48 patients with HT and obesity (group 1) and 34 patients with obesity (group 2). Patients under¬went fecal analysis for dysbiosis. The levels of complement, namely C3 and C4 and the concentration of immunoglobulins (IgA, Ig M, IgG) were determined by means of chromogenic analysis.

RESULTS

Results: During the clinical examination, constipation and flatulence were more often diagnosed in patients of group I (58.3% and 66.7%, respectively - p<0.001), while in patients of group 2 with increased BMI without thyroid dysfunction, a tendency to diarrhea was more often found, accompanied by periodic pain along the colon (50.0% and 32.3% of patients, respectively - p<0.001). Changes in the immunological status of patients in both groups were found. In patients with HT and increase of BMI an increase in serum IgA, IgM, IgG levels were found. An increase in serum immunoglobulins (A, M and G) was also diagnosed in group 2 of examined patients too.

CONCLUSION

Conclusions: 1. In patients with obesity decrease in the concentration of Bifidobacterium, Lactobacillus and increase in the number of Staphylococcus, Clostridium, Proteus and Klebsiella were detected, which is more pronounced in patients with a combination of obesity and hypothyroidism. 2. Impairment distinct of immu¬nological status in patients with hypothyroidism and obesity was diagnosed, which was manifested by increased levels of immunoglobulins, namly (A, M, G), as well as a decrease in blood serum complements (C3, C4). 3. The level of IgA, G directly depends on the decrese of Bifidobacterium, Lactobacillus and increse of Staphylococcus, Clostridium and Klebsiella in patients with obesity, which is more pronounced in patients with a combination of obesity and hypothyroidism.

PREDICTING PROGRESSION TYPE 2 DIABETES MELLITUS: A 3-YEAR FOLLOW-UP STUDY EXAMINING RISK FACTORS FOR TYPE 2 DIABETES IN PATIENTS WITH PREDIABETES

OBJECTIVE

Aim: To study the risk factors in patients with prediabetes that can lead to the progression of impaired glucose tolerance in the form of type 2 diabetes mellitus.

PATIENTS AND METHODS

Materials and methods: The selection of patients for this study was carried out on an outpatient basis at the Department of Therapy and Family Medicine, Uzhhorod National University. Patients with prediabetes were identified based on the American Diabetes Association criteria. Informed consent was obtained from all patients before the start of the study. Patients were randomly assigned to one of two groups: Group 1 (n=37) that received typical treatment according to the recommendations of the American Diabetes Association and the control Group 2 (n=42). At the 3rd year of the study, we determined the body mass index, glucose levels and glycated hemoglobin levels of the patients, also their medical documentation was analyzed and patients were interviewed about concomitant diseases.

RESULTS

Results: Analyzing the 3-year follow-up of patients with prediabetes, cases of type 2 diabetes mellitus were detected in both groups, but there is no statistically significant difference when comparing the indicators between the groups (p>0.05).

CONCLUSION

Conclusions: In our study, we analyzed the risk factors in patients with prediabetes that can lead to type 2 diabetes. During a 3-year follow-up, we identified cases of type 2 diabetes mellitus.