Hypothyroidism and its rapid correction alter cardiac remodeling

Area of Science:

• Cardiology
• Endocrinology
• Molecular Biology

Background:

• Thyroid disease significantly impacts cardiovascular health, leading to diverse pathological changes.
• Thyroid replacement therapy is considered for cardiac function preservation.
• The molecular and cellular effects of thyroid hormones on cardiac remodeling remain underexplored.

Purpose of the Study:

• To investigate the impact of hypothyroidism and subsequent thyroid replacement therapy on cardiac alterations at the molecular and cellular levels.

Main Methods:

• Thirty Wistar rats were divided into control and hypothyroidism-induced groups using 6-propyl-2-thiouracil (PTU).
• A subset of hypothyroid rats received L-thyroxine for rapid euthyroid restoration.
• Cardiac function was assessed via echocardiography, and serum/cardiac markers of inflammation, fibrosis, and stress were measured.

Main Results:

• Hypothyroidism significantly increased inflammatory markers (CRP, TNF-α, IL6), fibrotic markers (TGF-β1), and cardiac stress markers (BNP, cTnT).
• Cardiac remodeling gene expression, fibrosis, and functional decline with chamber dilation were observed in hypothyroid rats.
• Rapid correction of hypothyroidism improved cardiac function but paradoxically increased inflammation and fibrosis, causing myocardial infiltration.

Conclusions:

• Hypothyroidism is linked to cardiac dysfunction, fibrosis, and inflammation.
• Rapid correction of hypothyroidism can induce cardiac injury, highlighting potential risks.
• Findings offer new perspectives for managing hypothyroidism-induced heart disease.