A term neonate with unconjugated hyperbilirubinemia of 18 mg/dl on 20th day. All are common causes except –
Breast rnilk jaundice
Congenital cholangiopathy
G 6PD deficiency
Hypothyroidism
This child has unconjugated hyperbilirubinemia, while congenital cholangiopathy causes conjugated hyperbilirubinemia.
reastfeeding jaundice and Breastmilk jaundice 

There is strong association between exclusive breastfeeding and neonatal jaundice.
A few babies who remain on exclusive breast feed develop jaundice in the second week of life and continue well into the third month. This is called breastmilk jaundice.
A bilirubin level of over 20 mg/dl may be attained. (It is presumed to be due to inhibitory substances in the breastmilk that interfere with bilirubin conjugation e.g. pregananediol and free fatty acids).
Temporary interruption of breastmilk feeds will dramatically reduce the serum levels of bilirubin and there may be slight increase in bilirubin when breast feeding is resumed, but it never reaches the previous levels. Hypothyroidism  
Persistent elevation of indirect bilirubin is the first sign of congenital hypothyroidism in neonates.
This is due to decreased activity of UDPGT for weeks or months after birth.
At least 10% of all infants with congenital hypothyroidism will have jaundice as the presenting symptom.
Treatment with thyroxine promptly alleviates jaundice.

G-6PD deficiency 

There is hemolytic anemia that results in increased production of unconjugated bilirubin.