A newborn baby, noted to be jaundice at 30 hours of life. He was delivered term via vacuum assisted delivery. He is breastfeeding and suckling well, had passed meconium twice. Her brother had a history of neonatal jaundice requiring phototherapy. On examination, patient is alert with normal perfusion. Abdomen is soft, non tender with liver span of 1 cm below the costal margin. The rest of the examination is unremarkable. Bilirubin level is 255 What is the most useful investigation to determine cause of jaundice in this patient? A. Rh and ABO blood group B. Cord blood G6PD C. Cord blood TSH D. Liver function test E. Reticulocytes coun
Explain why the reticulocyte count is the best investigation