From the Guidelines
Uncontrolled hypothyroidism can lead to severe cardiovascular complications, including heart failure, hypertension, and atherosclerosis, due to increased peripheral vascular resistance and impaired cardiac function, emphasizing the need for prompt diagnosis and treatment. The sequelae of uncontrolled hypothyroidism are numerous and can affect multiple organ systems. In terms of cardiovascular complications, the low cardiac output in hypothyroidism is caused by bradycardia, a decrease in ventricular filling, and a decrease in cardiac contractility, as noted in a study published in Circulation 1. Systemic vascular resistance can increase by as much as 50%, and diastolic relaxation and filling are slowed. Although clinical heart failure is rare in hypothyroidism, because the cardiac output is usually sufficient to meet the lowered systemic demands, there are case reports of patients with hypothyroidism and dilated cardiomyopathy (DCM) in whom the cardiomyopathy improved with thyroid hormonal replacement 1. Some of the key sequelae of uncontrolled hypothyroidism include:
- Cardiovascular complications: atherosclerosis, heart failure, and hypertension
- Neurological manifestations: cognitive impairment, depression, peripheral neuropathy, and irreversible intellectual disability in children
- Metabolic consequences: dyslipidemia with elevated LDL cholesterol, weight gain, and insulin resistance
- Reproductive issues: menstrual irregularities, decreased fertility, and increased risk of pregnancy complications
- Musculoskeletal problems: myopathy, joint pain, and carpal tunnel syndrome
- Gastrointestinal effects: constipation and potential small intestinal bacterial overgrowth Treatment of hypothyroidism involves thyroid hormone replacement, typically with levothyroxine, at doses individualized based on weight, with regular monitoring of TSH levels 1. Early diagnosis and consistent treatment are essential to prevent these complications and improve quality of life.
From the Research
Sequelae of Uncontrolled Hypothyroidism
- Uncontrolled hypothyroidism can lead to severe and potentially life-threatening complications 2
- Clinical manifestations of hypothyroidism can range from life-threatening to no signs or symptoms, and can include fatigue, lethargy, cold intolerance, weight gain, constipation, change in voice, and dry skin 2
- If left untreated, hypothyroidism can lead to persistent complaints and decreased quality of life, despite biochemical treatment targets being reached 3
Treatment and Management
- The standard treatment for hypothyroidism is thyroid hormone replacement therapy with levothyroxine 2
- However, some patients may experience persistent symptoms despite optimal levothyroxine therapy, and may require alternative treatment approaches, such as combination therapy with liothyronine 3, 4, 5, 6
- The decision to start combination therapy should be a shared decision between the patient and clinician, and should be based on individual patient needs and preferences 3
Potential Complications
- Uncontrolled hypothyroidism can lead to a range of complications, including cardiovascular disease, osteoporosis, and cognitive impairment 2
- Patients with uncontrolled hypothyroidism may also experience decreased quality of life, and may require ongoing monitoring and management to prevent long-term sequelae 3