# Impact of Subclinical Hypothyroidism on Lipid Profile in Jeddah: A Retrospective Cohort Study

## TL;DR

This study finds that subclinical hypothyroidism is linked to worse lipid profiles and lower vitamin D levels, with treatment partially improving some markers.

## Contribution

The study provides new insights into lipid profile changes in subclinical hypothyroidism patients in Jeddah, Saudi Arabia.

## Key findings

- SCH patients had significantly lower HDL and higher LDL and TG levels compared to controls.
- Levothyroxine treatment increased total and LDL cholesterol levels in SCH patients.
- Lower vitamin D levels were observed in SCH patients before treatment.

## Abstract

Background

Patients with subclinical hypothyroidism (SCH) have a high serum concentration of thyroid-stimulating hormone (TSH), whereas their serum-free thyroxine concentrations are normal. Lipid metabolism is regulated in large part by thyroid hormones. It could be connected to a changed lipid profile. This study aimed to evaluate the relationship between SCH and alterations in the lipid profile.

Methodology

Data from 99 patients with SCH and 109 euthyroid cases were collected from King Abdulaziz Medical City, Jeddah, Saudi Arabia, from 2016 to 2022. Patients older than 18 years were included in the study. The groups were matched in terms of gender, age, and body mass index. SCH was defined as a TSH value of 4.5 to 10 mIU/L, and normal T4 as 5 to 18 μg/dL. Control cases had a normal TSH ranging from 0.45 to 4.5 mIU/L. The total serum cholesterol, high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, and triglyceride (TG) levels in both groups were examined and the results were recorded.

Results

In comparison to the control group, SCH patients had greater median glycated hemoglobin (HbA1C) (p = 0.001) and lower median vitamin D levels (p = 0.004) before therapy. Before therapy, SCH patients also showed considerably lower HDL levels and significantly higher LDL and TG levels (p < 0.001).

Conclusions

There is a substantial correlation between SCH and reduced HDL and vitamin D levels. It was linked to increased TG, LDL, and HbA1c levels. Only vitamin D and LDL were pathologically high. Treatment with levothyroxine raised total and LDL cholesterol levels. Future research should look into the affordability of treating SCH.