What are the consequences of undertreated hypothyroidism (underactive thyroid disease)?

Medical Advisory BoardAll articles are reviewed for accuracy by our Medical Advisory Board
Educational purpose only • Exercise caution as content is pending human review
Article Review Status
Submitted
Under Review
Approved

Last updated: April 23, 2025View editorial policy

Personalize

Help us tailor your experience

Which best describes you? Your choice helps us use language that's most understandable for you.

From the Guidelines

Undertreated hypothyroidism can lead to severe and potentially life-threatening complications, including myxedema coma, which is why timely and appropriate treatment is crucial. Patients with undertreated hypothyroidism may experience a range of symptoms, including persistent fatigue, weight gain, cold intolerance, constipation, dry skin, hair loss, muscle weakness, joint pain, depression, and cognitive issues like brain fog and memory problems 1. Cardiovascular effects are also a concern, with elevated cholesterol levels and increased risk of heart disease being potential consequences of undertreated hypothyroidism. Women may experience menstrual irregularities and fertility problems, highlighting the importance of proper thyroid function for reproductive health.

Some of the key health problems associated with undertreated hypothyroidism include:

  • Persistent fatigue and weakness
  • Weight gain and difficulty losing weight
  • Cold intolerance and sensitivity to cold temperatures
  • Constipation and digestive issues
  • Dry skin and hair loss
  • Muscle weakness and joint pain
  • Depression and cognitive issues
  • Cardiovascular effects, including elevated cholesterol levels and increased risk of heart disease
  • Menstrual irregularities and fertility problems in women

Proper treatment of hypothyroidism typically involves levothyroxine (synthetic T4) at individualized doses, with the goal of achieving optimal TSH levels and preventing complications 1. Regular monitoring of thyroid function is essential to ensure that treatment is effective and to prevent overtreatment or undertreatment, both of which can have negative consequences for the patient's health.

From the FDA Drug Label

In pediatric patients with congenital and acquired hypothyroidism, undertreatment may adversely affect cognitive development and linear growth Overtreatment or undertreatment with levothyroxine sodium tablets may have negative effects on growth and development, cardiovascular function, bone metabolism, reproductive function, cognitive function, gastrointestinal function, and glucose and lipid metabolism in adult or pediatric patients

Undertreated hypothyroidism can cause:

  • Adverse effects on cognitive development
  • Adverse effects on linear growth
  • Negative effects on growth and development
  • Negative effects on cardiovascular function
  • Negative effects on bone metabolism
  • Negative effects on reproductive function
  • Negative effects on cognitive function
  • Negative effects on gastrointestinal function
  • Negative effects on glucose and lipid metabolism 2

From the Research

Undertreated Hypothyroidism Complications

Undertreated hypothyroidism can lead to various complications, including:

  • Mental retardation and delayed milestones in infants 3
  • Heart failure, infertility, and myxedema coma in adults 3
  • Persistent symptoms such as fatigue, weight gain, cold intolerance, dry skin, and constipation 4, 5, 6
  • Reduced quality of life and decreased ability to perform daily activities 5, 6

Treatment and Management

Effective treatment and management of hypothyroidism can help prevent these complications:

  • Levothyroxine replacement therapy is the standard treatment for hypothyroidism 4, 5, 6
  • Combination therapy with levothyroxine and triiodothyronine may be considered for some patients, but its effectiveness is still being researched 4, 6, 7
  • Regular monitoring of thyroid-stimulating hormone levels and adjustment of medication dosage as needed is crucial for optimal management 3, 5

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

Have a follow-up question?

Our Medical A.I. is used by practicing medical doctors at top research institutions around the world. Ask any follow up question and get world-class guideline-backed answers instantly.