Little white spots (the so called leuconichias) are the result of a traumatism caused, for example, by when you have the habit of hitting the nails against the table. This may cause a serious problem. In case sudden or meanful changes occur on the nails look, it may mean some kind of disease. It is important, in this case, to see a doctor.
For example: when an individual presents severe malnutrition, after an illness or during some chemotherapy, the nails´formation gets unbalanced. Nails that grow entirely white may show some kind of infection.