Disorders can show up in your fingernails, so by looking at them you can get a good idea of your overall health.
Here is a list of just a few...
~Brittle Fingernails: possible kidney, circulation problems, iron deficiency and thyroid problems.
~Deep Blue Nail Beds: possible pulmonary constrictions such as emphysema and asthma.
~Red Skin at the Bottom of your fingernail: possible connective tissue disorder.
~Unusually Wide, Square Fingernails: possible hormonal disorder.
~Pitted Red-brown Spot and Frayed and Split Ends: possible psoriasis, vitamin c, folic acid and protein deficiency.
Remember this is advice not a diagnosis. Talking with your doctor is a good idea if you are concerned and have more questions.
Here's to your good health and beautiful fingernails.