The results are listed in Table 1. Methemoglobin levels in the 3 affected siblings (IV: 3, 4 and 9) were significantly elevated even though all 3 patients were being treated with ascorbic acid.

(A methemoglobin concentration above 20% should ... Indications for the initiation of NAC include a serum acetaminophen level on or above the Rumack-Matthew nomogram; situations in which a serum ...