Possible Complications

Among the general population, a number of known possible complications have been observed in people with thyroid disorders.

Hypothyroidism

Goiter:1 iodine deficiency or autoimmune destruction of the thyroid gland result in decreased production of thyroid hormone. In response, increased thyroid stimulating hormone is released from the pituitary to stimulate growth of the thyroid, which can cause a goiter.
   

Heart problems:2 hypothyroidism can result in an increased accumulation of low-density lipoprotein (LDL), resulting in an increased risk of heart disease. Long-standing hypothyroidism can also lead to heart enlargement and/or failure.



Mental health:3 slowed mental functioning and/or depression can occur early in hypothyroidism and may become more severe over time.



Peripheral neuropathy:4 long-term hypothyroidism can cause peripheral nerve damage. It is thought that this may be related to long-term metabolic dysfunction, although the link is not well understood.



Infertility:5 insufficient thyroid hormone levels can interfere with ovulation, impairing fertility. Hormone treatment for hypothyroidism may not fully restore fertility.



Birth defects:6 babies born to women with untreated thyroid disease may have a higher risk of birth defects than babies born to healthy mothers. Such children are also more prone to serious intellectual and developmental problems. Infants with hypothyroidism at birth are at risk of serious problems with both physical and mental development if left untreated. If the condition is diagnosed and managed within the first few months of life, the chances of normal development are greatly improved.



Hyperthyroidism

Goiter:1 enlargement of the thyroid gland, frequently due to excessive stimulation of hormone production. Large goiter can affect breathing and/or swallowing.


Heart problems:2 elevated thyroid hormones can cause tachycardia, atrial fibrillation and congestive heart failure.



Osteoporosis:7 long-term elevation of thyroid hormone levels can lead to osteoporosis via an inability to incorporate calcium into bones.



Eye problems:8 patients with hyperthyroidism may develop eye disorders, including bulging, red or swollen eyes, sensitivity to light and visual disturbance.



Skin problems:8 some patients with hyperthyroidism can develop dermopathy, causing redness and swelling, often on the shins and feet.



Thyrotoxic crisis:9 hyperthyroidism carries a risk of thyrotoxic crisis - a sudden intensification of symptoms, leading to fever, tachycardia and even delirium.





References

  1. American Thyroid Association. Goiter. 2005.
  2. Toft AD, Boon NA. Thyroid disease and the heart. Heart. 2000;84(4):455–460.
  3. American Thyroid Association. Long-term quality of life may be decreased in patients with hyperthyroidism caused by Graves’ disease. March 2006.
  4. National Institute of Neurological Disorders and Stroke. Peripheral neuropathy fact sheet. 2011.
  5. Kennedy RL, Malabu UH, Jarrod G, Nigam P, Kannan K, Rane A. Thyroid function and pregnancy: before, during and beyond. J Obstet Gynaecol. 2010;30(8):774–783.
  6. American Thyroid Association. Risk of birth defects in the babies of women with thyroid disease. 2002.
  7. Bassett JH, O’Shea PJ, Sriskantharajah S, et al. Thyroid hormone excess rather than thyrotropin deficiency induces osteoporosis in hyperthyroidism. Mol Endocrinol. 2007;21(5):1095-1107.
  8. American Thyroid Association. Graves’ disease. 2005.
  9. Karger S, Führer D. [Thyroid storm-thyrotoxic crisis: an update]. Dtsch Med Wochenschr. 2008;133(10):479–484.