These are the first symptoms of a…

Who Is Most at Risk?
Risk factors include:

Age over 50
Frequent hand washing
Repeated exposure to water
Chemical exposure
Nutritional deficiencies
Thyroid disease
Psoriasis
Eczema
Manual labor
Nail biting
How Doctors Diagnose the Cause
A healthcare provider or dermatologist will usually begin with a physical examination and medical history.

Depending on your symptoms, additional tests may include:

Blood tests for iron, vitamin B12, zinc, and thyroid function
Nail clippings or scrapings to check for fungal infection
Dermoscopy (a close examination of the nail)
Nail biopsy in rare cases if a tumor or other serious condition is suspected
Treatment
Treatment depends on the underlying cause.