ESPN 50th Annual Meeting

ESPN 2017


 
Thrombotic microangiopathy and breastfeeding. Where is the link?
JEAN DANIEL DELBET 1 IULIA STOICA 1 MARTIN AUGER 1 ALIZEE MICHEL 1 FERIEL FORTAS 1 TIM ULINSKI 1

1- PEDIATRIC NEPHROLOGY UNIT, ARMAND-TROUSSEAU HOSPITAL, AP-HP, UNIVERSITY PARIS 6, UPMC, PARIS, FRANCE
 
Introduction:

Thrombotic microangiopathy (TMA) is exceptional in infants and is mostly linked to thrombotic thrombocytopenic purpura via ADAMTS13 gene mutations or to atypical hemolytic uremic syndrome. However, vitamin B12 disorders can also be associated with TMA. We report a case of TMA in a 7-month-old patient due to severe vitamin B12 deficiency.

Material and methods:

A 7-month-old boy presented to our emergency department with marked pallor and severe asthenia. Laboratory tests revealed a severe anemia (haemoglobin 30 g/L), thrombopenia (26 x 109/ml) and 20% schistocytes. Initial investigations revealed also leukopenia, lymphopenia and megaloblastosis. Renal function was normal. Test for Shiga toxin producing Escherichia coli was negative, there was no complement activation and ADAMTS13 activity was normal.

Results:

He was rapidly treated by fresh frozen plasma infusion and a high dose of vitamin B12 (5,000 μg IM) at the time of admission, which allowed stopping the hemolysis within 12 hours. Further metabolic investigations revealed a markedly elevated urinary methylmalonic acid (MMA) at 1245 μmol/mmol creatinine (< 10 μmol/mmol creatinine). Vitamin B12 level was very high (>1500 pmol/l) and plasma homocysteine very low (< 3 µmol). Unfortunately, these tests were performed after plasma infusion and B12 injection. Five days after the beginning of the vitamin B12 treatment, MMA level was normal (2 μmol/mmol). Moreover, the patient received exclusively breastfeeding; his mother has a severe vitamin B12 deficiency (< 50 pmol/l) and we noted a progressive lethargy and a poor weigh gain since he was 4 months old, suggesting a vitamin B12 deficiency rather than a disorder in the cobalamin metabolism.

Conclusions:

Vitamin B12 deficiency can lead to severe TMA, even in infants. TMA is probably linked to hyperhomocysteinemia which is known to cause endothelial dysfunction.