Newborn screening tests are set of screening tests performed in the newborn period to diagnose a set of health conditions which are treated but rather difficult to be detected during the new born period. Newborn screening tests are recommended as many of the diseases for which screening tests are recommended may be only detected once irreparable damage has been done to the baby again in some of such diseases there is increased chance that death will be first manifestation of the disease.
These screening tests are usually carried out state or national government authorities to screen all the newborns in specific jurisdictions. Newborn screening tests were first started as a part of public health problem in the US in the year 1960 and then many countries have now started newborn screening tests. The first disease identified in new screening tests program was phenylketonuria.

What are the targeted disorders?
There are several criteria which determine whether screening tests for a particular disease should be carried out in the newborn period. These are
1. The disease must have an accepted management protocol and early intervention (diagnosis and treatment) will change the long term outcome of the disease
2. The natural history of the diseases should be understood thoroughly
3. There should be clear cut criteria regarding who should be screened for the disease
4. There should be reliable screening tests for early detection of the diseases and the tests should be acceptable to general public.
In the US screening tests in the newborn period are carried out for 54 conditions whereas in UK screening tests are carried out for only two health conditions phenylketonuria and medium chain acyl CoA dehydrogenase deficiency.
The tests included in the newborn screening test programs are dependent upon certain factors namely legal issue, prevalence of a disease in that particular country, political stand point, availability of resources, follow-up of the babies detected with the diseases included in the screening tests, social stand point, etc.
The most commonly included tests in the newborn screening program around the world are phenylketonuria, the fatty acid oxidation disorders like medium chain acyl CoAdehydrogenase deficiency, hormonal disorders namely congenital hypothyroidism and congenital adrenal hyperplasia, hemoglobinopathies, diseases which leads to abnormal hemoglobin production (the most commonly included diseases in this category is sickle cell anemia, organic acidemias, cystic fibrosis, diseases affecting urea metabolism namely citrullinemia, argininosuccinic aciduria and argininemia, lysosomal storage diseases namely Krabbe disease, Guacher disease, Pompe disease, Fabry disease, Niemann Pick disease etc, congenital heart diseases, severe combined immunodeficiency, Duchenne muscular dystrophy etc.

Ethical Issues
Inclusion of screening tests for certain rare diseases are opposed by even by some of the health care personnel as there is concern about follow up, availability of effective treatment for certain diseases, chance of false positive results etc.
Again there are also some positive impacts of including screening tests for some of the rare diseases. In the US two babies were suffering from Glutaric academia type 1. In one of the babies the disease was detected as the hospital was participating in pilot program which included screening test for the said disease and the baby was managed with dietary modification and vitamin supplements whereas in the second baby in whom the hospital performed screening tests only for the 4 diseases approved by the state law, the disease was finally detected when there were irreversible damage.