A 26-week-old baby was brought to the pediatric clinic because of increasing lethargy and cyanosis. The infant has been in good health at birth, and the mother had attempted breast-feeding. A blood sample was collected and a positive test for methemoglobinemia was obtained. The baby then was treated with intravenous ascorbate and methylene blue. Within 2 days the child was alert, and the cyanosis had disappeared. It is known that methemoglobin has absorption spectra maxima at 500 nm and 631 nm. Answer the following questions:_______.
1. What is the chemical difference between hemoglobin and methemoglobin, and how do their oxygen capacities compare?
2. How do you analyze the sample blood to detect methemoglobin?
3. What is the cause of the cyanosis associated with toxic methemoglobinemia?
4. What is the biochemical basis for treatment of toxic methemoglobinemia with ascorbate and methylene blue?
