Background: Increased oxidative stress causes damage to all molecular targets potentially because of discrepancy between antioxidant defensive mechanisms and reactive oxygen species (ROS). Previous studies have reported enhanced oxidative stress in subclinical hypothyroidism (SCH).Dyslipidemia and oxidative stress screening can help the overall management of hypothyroidism and decrease cardiovascular morbidity. Objective: This study evaluates the degree of oxidative stress in hypothyroid dysfunction, including low-normal thyroid states, by estimating some serum oxidative biomarkers and correlating them to lipid profile as well as defining the cut-off value of thyroid-stimulating hormone, free thyroxin, and free triiodothyronine associated with increased oxidative biomarkers. Methods: This study included 60 adult patients with hypothyroidism who were subdivided into three equal groups. Group A included overt hypothyroidism, group B consisted of subclinical hypothyroidism (SCH), and group C that contained low-normal thyroid status (high TSH, low FT4 and FT3 levels within the normal values). A control group, which included 20 healthy control subjects. Oxidative biomarkers, thyroid hormones, and lipids were estimated. Results: Urinary allantoin and serum MDA were significantly higher in groups A, B, and C compared with the control group (P < 0.001) with a significant positive correlation with TSH, total cholesterol, and low-density lipoprotein cholesterol (P < 0.001). Significant dyslipidemia was demonstrated in patients with overt hypothyroidism and SCH compared to the control group (P < 0.001 and P = 0.008 respectively). FT3 was an independent predictor for MDA and urinary allantoin. The receiver operating characteristic curve analysis detected the cut-off values of TSH (≥ 4.2 and 3.6), FT4 (≤ 1 and 1.3), and FT3 (≤ 3.06 and 3.08) and predicted allantoin and MDA elevation, respectively (P < 0.001) and hence oxidative stress. Conclusion: Hypothyroidism, even low-normal thyroid status is a state of increased oxidative stress. The efficacy of levothyroxine treatment and antioxidant supplements in these individuals should be tested.