Nail Changes Associated With Thyroid Disease

The major classifications of thyroid disease include hyperthyroidism, which is seen in Graves disease, and hypothyroidism due to iodine deficiency and Hashimoto thyroiditis, which have potentially devastating health consequences. The prevalence of hyperthyroidism ranges from 0.2% to 1.3% in iodine-sufficient parts of the world, and the prevalence of hypothyroidism in the general population is 5.3% in Europe and 3.7% in the United States.¹ Thyroid hormones physiologically potentiate α- and β-adrenergic receptors by increasing their sensitivity to catecholamines. Excess thyroid hormones manifest as tachycardia, increased cardiac output, increased body temperature, hyperhidrosis, and warm moist skin. Reduced sensitivity of adrenergic receptors to catecholamines from insufficient thyroid hormones results in a lower metabolic rate and decreases response to the sympathetic nervous system.² Nail changes in thyroid patients have not been well studied.³ Our objectives were to characterize nail findings in patients with thyroid disease. Early diagnosis of thyroid disease and prompt referral for treatment may be instrumental in preventing serious morbidities and permanent sequelae.

Methods

PubMed, Scopus, Web of Science, and Google Scholar were searched for the terms nail + thyroid, nail + hyperthyroid, nail + hypothyroid, nail + Graves, and nail + Hashimoto on June 10, 2020, and then updated on November 18, 2020. All English-language articles were included. Non–English-language articles and those that did not describe clinical trials of nail changes in patients with thyroid disease were excluded. One study that utilized survey-based data for nail changes without corroboration with physical examination findings was excluded. Hypothyroidism/hyperthyroidism was defined by all authors as measurement of serum thyroid hormones triiodothyronine, thyroxine, and thyroid-stimulating hormone outside of the normal range. Eight studies were included in the final analysis. Patient demographics, thyroid disease type, physical examination findings, nail clinical findings, age at diagnosis, age at onset of nail changes, treatments/medications, and comorbidities were recorded and analyzed.

Results

Nail changes in patients with thyroid disease were reported in 8 studies (7 cross-sectional, 1 retrospective cohort) and are summarized in the Table.^4-11 The mean age was 41.2 years (range, 5–80 years), with a higher representation of females (range, 70%–94% female). The most common nail changes in thyroid patients were koilonychia, clubbing, and nail brittleness. Other changes included onycholysis, thin nails, dryness, and changes in nail growth rate. Frequent physical findings were xerosis, pruritus, and alopecia.

Both koilonychia and clubbing were reported in patients with hyperthyroidism. In a study of 32 patients with koilonychia, 22 (68.8%) were diagnosed with hyperthyroidism.¹⁰ Nail clubbing affected 7.3% of Graves disease patients (n=150)⁶ and 5.0% of hyperthyroid patients (n=120).⁷ Dermopathy presented more than 1 year after diagnosis of Graves disease in 99 (66%) of 150 patients as a late manifestation of thyrotoxicosis.⁶ Additional physical features in patients with Graves disease (n=150) were pretibial myxedema (100%), ophthalmopathy (99.0%), and proptosis (88.0%). Non–Graves hyperthyroid patients showed physical features of soft hair (83.3%) and soft skin (66.0%).⁷

Nail brittleness was a frequently reported nail change in thyroid patients (4/8 studies, 50%), most often seen in 22% of autoimmune patients, 19.6% of nonautoimmune patients, 13.9% of hypothyroid patients, and 9.2% of hyperthyroid patients.^5,8 For comparison, brittle nails presented in 10.8% of participants in a control group.⁵ Brittle nails in thyroid patients often are accompanied by other nail findings such as thinning, onycholysis, and pitting.

Among hypothyroid patients, nail changes included fragility (70%; n=50), slow growth (48%; n=50), thinning (40%; n=50), onycholysis (38%; n=50),⁷ and brittleness (13.9%; n=173).⁵ Less common nail changes in hypothyroid patients were leukonychia (9.4%; n=32), striped nails (6%; n=50), and pitting (1.2%; n=173).^5,7,11 Among hyperthyroid patients, the most common nail changes were koilonychia (100%; n=22), softening (83%; n=120), onycholysis (29%; n=14), and brittleness (9.2%; n=173).^5,7,9,10 Less common nail changes in hyperthyroid patients were clubbing (5%; n=120), thinning (4.6%; n=173), and leukonychia (3%; n=120).^5,7

Additional cutaneous findings of thyroid disorder included xerosis, alopecia, pruritus, and weight change. Xerosis was most common in hypothyroid disease (57.2%; n=460).⁴ In 2 studies,^8,9 alopecia affected approximately 70% of autoimmune, nonautoimmune, and hyperthyroid patients. Hair loss was reported in 42.6% (n=460)⁴ and 33.0% (n=36)⁹ of hypothyroid patients. Additionally, pruritus affected up to 28% (n=32)¹¹ of hypothyroid and 16.0% (n=120)⁷ of hyperthyroid patients and was more common in autoimmune (41%) vs nonautoimmune (32%) thyroid patients.⁸ Weight gain was seen in 72% of hypothyroid patients (n=32),¹¹ and soft hair and skin were reported in 83.3% and 66% of hyperthyroid patients (n=120), respectively.⁷ Flushing was a less common physical finding in thyroid patients (usually affecting <10%); however, it also was reported in 17.1% of autoimmune and 57.1% of hyperthyroid patients from 2 separate studies.^8,9