Dry, brittle nails that frequently crack or split have been linked to thyroid disease. Cracking or splitting combined with a yellowish hue is more likely due to a fungal infection.

• 干、脆甲症常表现指甲裂开或劈开，与甲状腺疾病有关。霉菌感染更可能造成指甲裂开或劈开并伴有微黄色改变。