Endocrine Abstracts

A 5-month-old child presented with progressive lethargy and loss of motor skills. His mother had pre-existing type 1 diabetes with good glycaemic control throughout gestation (HBA1c 7.3% at booking, 5.5% at 20 weeks). She was euthyroid during pregnancy but had a high titre of thyroid microsomal antibodies (25600). Full blood count was normal at booking and delivery (haemoglobin 12.3 and 11.8 grams per decilitre, MCV 83 and 84 respectively). She was not vegetarian.
The child's head circumference at birth was on the 91(super)st(/super) centile (36 cm) and birth weight was on the 25(super)th(/super) centile (2.94 kilograms at 38 weeks and 3 days). He was exclusively breast-fed. From 10 weeks, weight gain slowed. At 5 months, head circumference was on the 0.4(super)th(/super) centile; he was floppy and had lost the ability to roll over. He was anaemic with low serum vitamin B12 and raised urinary methylmalonic acid and homocystine.
The mother had developed borderline anaemia (haemoglobin 11.2 grams per decilitre) and was vitamin B12 deficient (serum true cobalmin 90 nanograms per litre, reference range 200-900) with biopsy-proven autoimmune gastritis. She had also developed compensated primary autoimmune hypothyroidism: free T4 13.4 picomoles per litre (reference range 11-24), TSH 11.2 milliunits per litre (reference range 0.1-5.5).
The child received parenteral vitamin B12 and carnitine supplements. His mother was established on parenteral vitamin B12 and thyroxine 75 micrograms per day. The baby's development quickly improved and by 22 months milestones were normal. Head circumference reached the 9(super)th(/super) centile. Homocystinuria disappeared and methylmalonate levels near-normalised.
Methylmalonic aciduria and B12 deficiency in the child were probably secondary to intrauterine and neonatal B12 deficiency caused by maternal pernicious anaemia. The condition has been reported several times previously in the offspring of vegetarian mothers, but very rarely in association with pernicious anaemia.