Diseases of the nails can affect the appearance of the nail plate and the surrounding tissues. The nail can also reflect on other internal health conditions of the body. Abnormal changes of the nail can occur in its:

• Shape
• Surface
• Texture
• Colour

The scope of this area is very wide and it is not possible to list them all out here. The following only mentions some of the more common examples, and if there is any doubt, medical advice should be required.

Shape

• Chronic heart and lung diseases will cause a drop in the blood’s oxygen level. The nail will become a round bulb shape and the colour will become purplish-red.
• Chronic iron-deficiency anaemia will cause a spoon-shaped indentation. The colour will appear white.
• Nails that lack proper care and trimming for a long time will have an exaggerated curve inwards like a clamp on the nail bed.

Surface

• Longitudinal grooves along the length can be a normal phenomenon, but it can be due to a benign tumour or wart in the matrix.
• Longitudinal raised lines have many causes. It can be simply normal, but can also be due to old age, self-inflicted injuries, genetics, and tumours.
• Horizontal lines may represent a severe illness at a certain time in the past, or due to eczema of the surrounding skin.
• Small, pitted holes may be due to alopecia areata, psoriasis, eczema, but occasionally may happen in normal situations.
• Roughened surfaces are usually related to long-term exposure of irritant liquid, or may be related to psoriasis, fungal infection, or eczema.
• Brittle, flaky surface is usually due to long term contact with irritant liquid or water, but may be related to old age or psoriasis.

Texture

• Fungal infection, psoriasis can make the nail thickened, brittle, and easy to crumble.
• Localised injury; chemicals; long-term water contact; and iron, vitamins A, C, and B6 deficiency will make the nail softened and brittle.

Colour

Some medications and chemicals may change the colour of the nails. It may be contacted accidentally or is used for a medical treatment. Colour changes due to diseases are usually white, black, brown, green or yellow.

• White: can be due to separation of the nail from the nail bed, fungal infection, psoriasis, heart and lung diseases, kidney diseases, or anaemia.
• Black or brown: can be due to clotted blood under the nail after an injury, fungal infection, a naevus or rarely a malignant skin tumour (melanoma) in the nail bed.
• Green: usually due to bacterial or candidal infection.
• Yellow: can be due to over-slow growth, candidal infection, or medications.

Lastly, the nail plate may be separated from the nail bed in a lot of situations, such as trauma, psoriasis, eczema, fungal infection, iron-deficiency anaemia, hyperthroidism, pregnancy, or any major illnesses.