Mar 12, 2010
Journal of Inherited Metabolic Disease
Editor, I read the recent report by Carrillo-Carrasco et al. with a great interest (Carrillo-Carrasco et al. 2009). They reported a case of cobalamin C (CblC) and concluded that “higher hydroxocobalamin (OHCbl) doses might be required to achieve an optimal biochemical response in CblC patients, but it is unknown whether it may slow or eliminate other complications (Carrillo-Carrasco et al. 2009).” Indeed, the proper dosage of OHCbl in CblC patients is still a myth. The authors reported on only one successful case, and the monitored outcome is only a short-term one. The success might be an incidental finding. Although there are some reports on long-term use of OHCbl, there is no evidence that a dose adaptation brings a significant improvement in outcome. Andersson et al. reported that developmental delay of variable severity was always present without clinical correlation to age at diagnosis or treatment (Andersson et al. 1999). Indeed, it is not surprising that an increased dose of OHCbl might lead to an increase in related substances in the metabolic pathway within a patient’s body. However, the question is whether this increase has clinical impact and leads to any side effect. OHCbl can also significantly increase blood pressure (Uhl et al. 2008), and this should be a concern in escalating the dosage of this drug.