Table 1.
Secondary causes of brittle nails.
| Dermatological | Psoriasis |
| Lichen planus | |
| Eczema | |
| Darier’s disease | |
| Alopecia areata | |
| Nutritional deficiencies | Vitamins A, B, C, D and E |
| Iron | |
| Zinc | |
| Selenium | |
| Medications | Retinoids |
| Antiretrovirals | |
| Chemotherapeutic agents | |
| Arsenic | |
| Penicillamine | |
| Systemic | |
| Vascular | Peripheral artery disease |
| Arteriosclerosis | |
| Raynaud’s disease | |
| Hematological | Iron deficiency anaemia |
| Polycythaemia vera | |
| Endocrinological | Thyroid disease |
| Hypothyroidism, hyperthyroidism | |
| Hypopituitarism | |
| Diabetes mellitus | |
| Osteoporosis | |
| Other | Pregnancy |
| Sarcoidosis | |
| Amyloidosis | |
| Gout | |
| Malnutrition | |
| Neuropathy | |
| Infectious | Onychomycosis |
| Pulmonary tuberculosis | |
| Bronchiectasis | |
| Syphilis | |
| Hepatitis B and C |