Vitamin B₁₂ Administration by Subcutaneous Catheter Device in a Cobalamin A (cblA) Patient

Cobalamin A deficiency (cblA) is an inherited disorder of intracellular cobalamin metabolism, caused by impaired 5'-deoxy-adenosylcobalamin (AdoCbl) synthesis. Hydroxocobalamin (OHCbl) is the cornerstone of cblA treatment because vitamin B12 may completely restore AdoCbl deficiency. Parenteral administration, intravenous, subcutaneous or intramuscular, is generally required to achieve effect. Daily injections represent a problem for the parents and the caregivers, and this may lead to poor compliance and scarce adherence to the long-term treatment.Our report describes the case of a patient with cblA deficiency, diagnosed by newborn screening, positively treated with daily OHCbl administration by a subcutaneous injection port (i-port advanceTM). After the insertion of the device, we checked methylmalonic acid (MMA) levels weekly for the first month and then monthly. MMA level remained always in the normal range.To date, placement of a subcutaneous catheter to minimize the pain related to parenteral vitamin B12 punctures has been described only in a patient with deficiency of the enzyme methylmalonyl-CoA mutase (MUT). No other experiences are described in the literature.Our case shows that OHCbl administration using a subcutaneous catheter is safe and effective even in patients with cblA deficiency. The use of subcutaneous devices may reduce difficulties in providing parenteral daily injections which is the main reason discouraging physicians and families to use such an invasive treatment. Moreover, our experience may be translated to other inherited metabolic disorders, such as cobalamin C (cblC) disease, which may require daily parenteral drug administration.