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Hydroxocobalamin dose escalation improves metabolic control in cblC.
N Carrillo-Carrasco1, J Sloan1, D Valle2
1Organic Acid Research Section, Genetics and Molecular Biology Branch, National Human Genome Research Institute, National Institutes of Health, Building 49, Room 4A18, Bethesda, MD, 20892, USA.
Journal of Inherited Metabolic Disease
|October 13, 2009
Summary
Cobalamin C (cblC) is a metabolic disorder treated with hydroxocobalamin (OHCbl). Higher OHCbl doses improved metabolic markers in a patient with cblC, suggesting potential benefits for treatment optimization.
Area of Science:
- Biochemistry
- Genetics
- Metabolic Disorders
Background:
- Cobalamin C (cblC) deficiency is the most common inherited disorder of intracellular cobalamin metabolism.
- Newborn screening can detect cblC, which presents acutely and can be fatal if untreated.
- Intramuscular hydroxocobalamin (OHCbl) is the standard treatment, but lacks formal dosing guidelines.
Observation:
- A 13-year-old boy with cblC experienced worsening metabolic parameters despite standard treatment.
- The patient's OHCbl dosage was increased from 1 mg to 20 mg IM daily.
- A dose-dependent biochemical response was observed with increasing OHCbl dosage.
Findings:
- Plasma methylmalonic acid (MMA) decreased by 80% (25 to 5.14 µmol/L).
- Total homocysteine (tHcy) levels reduced by 55% (112 to 50 µmol/L).
- Methionine levels more than doubled (17 to 36 µmol/L).
Implications:
- Higher intramuscular OHCbl doses may be necessary for optimal biochemical control in cblC patients.
- Further clinical trials are needed to evaluate the efficacy of high-dose OHCbl therapy.
- The long-term impact of increased OHCbl dosing on cblC complications requires investigation.
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