Blue lips and blue nail beds in a child usually mean one of two things, and both are urgent. Either the heart is failing to route blood properly, or the lungs are failing to oxygenate it. Cardiology and pulmonology get called, an echocardiogram gets ordered, and the search begins.
In a small number of patients, every one of those tests comes back normal, over and over, sometimes for years. The child is active, growing normally, and persistently blue.
