This document discusses various nail abnormalities including brittle or crumbly nails which can be caused by aging, water/chemical exposure, fungal infection, lichen planus, thyroid disorders or psoriasis. Discolored nails are also covered, such as yellow nails from fungus or psoriasis. Loose nails can result from injury, infection or conditions like amyloidosis. Koilonychia causes indented spoon-shaped nails due to iron deficiency or other issues. Clubbing refers to unusually curved fingertips/nails associated with lung or heart conditions. Common treatments involve moisturizers, antibiotics or soaking affected areas.