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.
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IMD WATCH 3 PLAN AND IMPLEMENT NUTRITION AND DIETETIC INTERVENTION The patient was commenced on: • 40Kcals/kg/day; • 1.1g/kg/day of protein made up of (40g from diet and 30g from a medical protein supplement for PA); • British Inherited Metabolic Disease Group (BIMDG) emergency regimen; IV dextrose and oral glucose polymer for illness and high risk times such as two weeks postpartum. She was advised to avoid fasting, eat every three hours and have a bedtime snack. Standard pregnancy food safety advice was also given, including limiting caffeine, and avoiding alcohol. Vitamin D, folic acid 5mg and omega-3 supplements were continued and a calcium supplement of 1,000mgs was added to meet the requirement for twin pregnancy.2 Dietary protein was increased by 15% at week gestation 6, 11 and 20 due to low branched chain amino acids. The protein intake from medical protein supplement was increased in the third trimester to provide a total protein intake of 1.2g/kg/day. Calories were increased in the second and third trimester and were extrapolated from single foetus requirements.3 Her total weight gain was within the recommended range for twin pregnancy 25.5kgs (17 to 25kgs).4 Twin girls were delivered via C section at 33 weeks due to a shortened cervix, signs of premature labour and breech of first infant. They weighed 1.55kg and 1.34kg. Breastfeeding was encouraged, but infant formula was used. 4 MONITOR AND REVIEW Dietetic management postpartum There is a risk of decompensation at birth and for the first two weeks postpartum.6 It is thought to relate to metabolic stress of changes to the puerperium and increased protein load for catabolism following involution of the uterus. For the first two weeks postpartum: • the patient restricted her dietary protein intake and continued her emergency regimen; • extra non protein calories were given in addition, which included prescribable low protein foods and glucose polymer; • IV dextrose was continued until she was eating well; • the medical protein supplement was weaned down and stopped; • energy intake was reduced after initial 14 days back to normal requirements of 35.3Kcals/kg5 and dietary protein was increased up to safe levels;3 • lower dose calcium, vitamin D, magnesium and omega-3 supplement and L carnitine were continued. 5 EVALUATION There is limited literature on the management and pregnancy outcomes for women with PA. Close monitoring by the multidisciplinary team is needed to ensure metabolic stability and normal growth and development of the foetus.
References 1 Schwoerer J et al (2016). Successful pregnancy and delivery in a women with propionic acidaemia from the Amish community. Molecular Genetics and Metabolism reports. Jun 2; 8: 4-7 2 Pen (2016). Dietitians of Canada Multi fetal practice guidance summary .Practice Evidence in Nutrition. www.pennutrition.com/ KnowledgePathway.aspx?kpid=13491&pqcatid=146&pqid=13522. Last accessed 20.7.17 3 World Health Organisation, Food and Agriculture Organisation of the United Nations, United Nations University (2007). Report of a joint FAO/ WHO/UNU expert consultation (WHO Technical Report Series 935). Protein and amino acid requirements in human nutrition. World Health Organisation, Food and Agriculture Organisation of the United Nations, United Nations University 4 Rasmussen KM and Yaktine AL (2009). Weight gain during pregnancy: re-examining the guidelines. Institute of Medicine (US) and National Research Council (US) and Committee to Re-examine IOM pregnancy weight guidelines. Washington (DC): National Academies press (US) 5 Baumgartner et al (2014). Proposed guidelines for the diagnosis and management of methylmalonic and propionic academia. Orphanet J Rare Dis 2014; 9: 130 6 Murphy (2015). Pregnancy in women with Inherited Metabolic Disease. Obstet Med June; 8(2) 61-67
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