Background: Hypothyroidism is a common endocrine disorder associated with several metabolic abnormalities, including dyslipidemia. The prevalence of dyslipidemia in hypothyroidism and the effect of thyroid hormone replacement therapy on lipid profile are well-established. However, the association between lipid profile and age and sex in patients with hypothyroidism is less clear. Methods: We conducted a retrospective study of 100 patients with hypothyroidism to evaluate their lipid profile and investigate the effect of thyroid hormone replacement therapy on lipid levels. We also analyzed the association between lipid profile and age and sex in this patient population. Results: Our study found a high prevalence of dyslipidemia in patients with hypothyroidism, with elevated total cholesterol and LDL cholesterol being the most commonly observed abnormalities. Thyroid hormone replacement therapy significantly improved lipid profile values in patients with hypothyroidism, with a decrease of 20% in total cholesterol and 25% in LDL cholesterol. We also found an age-related increase in total cholesterol and LDL cholesterol and a decrease in HDL cholesterol, while HDL cholesterol was significantly lower and triglycerides were significantly higher in females. Conclusion: Our study highlights the importance of screening and monitoring lipid profile in patients with hypothyroidism, especially those who are older or female. Thyroid hormone replacement therapy significantly improves lipid profile values in patients with hypothyroidism. Age and sex are important factors that influence lipid profile in patients with hypothyroidism. Therefore, appropriate attention should be given to these factors when managing dyslipidemia in patients with hypothyroidism.