I am due with my 4th in February, though I haven't been active on this DDC I still check in. My 3rd was diagnosed with a metabolic disorder with her first (24 hour) heel stick. She has Biotinidase Deficiency. It is easily treated with a daily dose of biotin (which is a B vitamin). As long as she has that daily dose, she should never show any signs or effects of the disorder. If we didn't start her in biotin immediately, however, she could have suffered with deafness, seizures and even death. The test checks for enzyme activity for her particular disorder, and other metabolic disorders, so these are accurate immediately, without waiting for 24 hours of milk. I know her disorder is rare, in fact we had never even heard of it before her diagnosis, but there is no way of knowing if your child is one of those rare ones that will be affected or not. It was certainly worth that minute of discomfort to get her diagnosed and treatment begun so quickly and to know that she should never show any signs of her disorder.