IMD WATCH
Melanie Hill RD, Sheffield Teaching Hospitals NHS Foundation Trust Melanie works as a Specialist Dietitian for adults with inherited metabolic disorders at Sheffield Teaching Hospitals NHS Foundation Trust. She started her career in Dietetics in 1997 and has worked in a variety of specialities, more recently working in metabolic disorders and managing pregnancy in women with metabolic disorders.
PROPIONIC ACIDAEMIA AND A TWIN PREGNANCY: CASE STUDY Propionic acidaemia (PA) is an autosomal recessively inherited metabolic disease. It is a rare disorder of 1:50,000 to 1 in 100,000 births.1 It is caused by a deficiency in the enzyme Propionyl CoA Carboxylase. Propionyl CoA is produced in the metabolism of amino acids valine, isoleucine, threonine and methionine and odd chain fatty acids. Deficiency results in an accumulation of organic
acids including propionate which are toxic to tissues. Patients risk decompensation, severe acidosis and hyperammonaemia. In pregnancy, women need to be managed closely to prevent metabolic decompensation.
1 ASSESSMENT Patient: age 36 and six weeks pregnant The patient was diagnosed with PA at nine months old following investigations for hypotonia and slow motor development. She was treated with a low protein diet and protein supplement free of amino acids: valine, methionine, isoleucine and threonine. She also took Ketovite, calcium, Biotin and L-carnitine. Her past medical history included persistent ECG T wave inversions in anterolateral leads, fainting episodes, one episode of decompensation at the age of eight and hypothyroidism. She presented in our clinic at age 36 and six weeks pregnant after a third attempt of in vitro fertilisation (IVF). She had a decompensation two weeks after embryo implantation secondary to infection. Prior to pregnancy, her weight was 59.3kgs, BMI 21.7kg/m2. Dietary intake was 2,100 calories and 38g protein per day (0.65g/kg/day). She was taking folic acid 5mgs, magnesium sulphate 50mg bd, omega-3 supplement 1 gram/day, a pre-natal vitamin and mineral, vitamin D 25mcgs, thyroxine 137mcgs and carnitine 3g bd. 2 IDENTIFICATION OF NUTRITION AND DIETETIC DIAGNOSIS Aims of treatment • To reduce the production of propionate and other metabolites by using a low protein diet to restrict pre cursor amino acids. •
To avoid fasting, thereby limiting lipolysis and in turn oxidation of odd chain fats.
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To provide sufficient calories, protein and micronutrients to support growth of foetuses.
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To maintain metabolic control throughout pregnancy, peri- and postpartum period.
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To provide an emergency regimen for illness and high risk situations, i.e. for two weeks postpartum.
www.NHDmag.com October 2017 - Issue 128
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