Assessing and managing micronutrient deficiency in a paediatric patient

Deficiency of iron, iodine and vitamin A are widespread globally, with particularly detrimental effects for infants and children

Dr Dónal Farrell, Consultant Dietitian, Paediatrics, Ireland

November 23, 2019

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  • With improved overall nutrition and food availability, these have been observed less and less in the developed world.1

    However, it is still common in many populations, particularly children, where there are high demands for growth and development. In Ireland, one in 10 toddlers has inadequate intakes.2 Inadequate vitamin A and D intakes have also been highlighted in our toddler population.2 Children with autism often have particularly restricted diets and may be at greater risk of micronutrient deficiency. Interestingly, recent papers from the US and Ireland have highlighted vitamin C deficiency3 and concomitant vitamin A and D deficiency4 respectively in children with autism. 

    Micronutrient deficiencies can occur in all settings and the registered dietitian (RD) is an important member of the team when it comes to assessing, intervening and monitoring the patient. In this piece, the case of a child with an extremely restricted oral diet presenting with micronutrient deficiency is discussed. 


    Client history: Suspected autistic spectrum disorder, global developmental delay, non-verbal and poor sight. 

    Medical investigations and observations: The child presented at three years old with profound iron deficiency anaemia. The child had an extremely restricted diet and was referred to dietetics. She was not linked with community services at presentation. The child was also referred to dentistry.  

    Biochemistry/Lab values: Hypochromic, microcytic anaemia was present with low serum ferritin. Serum Iron was also low. C-reactive protein (CRP) was within reference range (see Table 1).

    Medications and prescribed nutrition: The child was started on 5ml of ferrous fumarate once daily, equal to 45mg of elemental iron or ~3mg/kg per day. No other medications or supplements were used.

    Nutrition-focused physical findings: The patient presented with no overt symptoms of deficiency (eg. nail ridges, koilonychia, glossitis, stomatitis). Poor dentition was noted with significant plague build-up. No lower gastrointestinal issues were reported at baseline.

    Anthropometry: Weight and height on WHO-UK centile charts were on the 98% and 91% respectively and no historical growth issues were evident 

    Nutrition-related history: (Summary) Intake was high in sugar and refined carbohydrate. Based on growth, overall energy need was met along with sufficient protein. Most importantly, the diet lacked almost any source of iron or copper. Calcium and tannin intake were potentially exacerbating inadequate iron intake. Milk alone is, however, a remarkably complete food providing significant contributions of a host of micronutrients (see Table 2). Dietary analysis using food composition data showed that significant additional contributions of other nutrients not provided by dairy were supplied by popcorn, waffles and crisps such as thiamine, vitamin C, E and K, zinc and manganese – 50-100% European Food Safety Authority (EFSA) recommended daily allowances (RDAs)/adequate intakes (AIs). 

    Given suboptimal intakes, serum vitamin D, folate, selenium and copper were analysed. Vitamin A was analysed to rule out any contribution to existing visual impairment. It is important to note that serum copper and selenium are not ideal markers of status, but are used clinically.5 See Table 3 for further biochemical results.

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    A full blood count (FBC) and serum ferritin would be repeated in three months and supplementation continued for a further one to two months ideally. Thereafter, routine annual bloods would be done including an FBC, serum ferritin and CRP. These tests are inexpensive and widely available. Unfortunately, oral diet was not amenable to significant change. Given communication and behavioural challenges, management focused on ensuring adequate intake by supplementation and reassuring parents while maximising quality of life and the feeding experience. Total milk intake was high but not excessive. It was enjoyed and nutritionally-dense; intake was maintained at up to 800ml per day.

    Iron and Vitamin C

    High-dose iron appeared to be causing significant GI discomfort. Once ferritin and FBC levels were normal, a plan was devised to trial low dose (5mg) iron supplement with vitamin C. This would be taken an hour apart from any dairy to maximise absorption. The patient had weaned off tea, which might otherwise compromise iron absorption due to the tannin content. 

    Folate and vitamins A, D and E

    Initially, 3000IU vitamin D a day for eight weeks, followed by maintenance dose of 400IU thereafter indefinitely (in line with local practice). A shop-bought fortified milk was suggested; this contained added folic acid to meet the RDA along with additional vitamin A, D and E. A repeat folic acid level would be carried out in six months. If within range, no routine screens were necessary if adequate intake was maintained. Vitamin D levels would be done at six months, one year and as indicated thereafter. Additionally, if levels were at least 70nmols/L, the 400IU supplement could be discontinued given the expected dose-response relationship.6

    Copper and selenium 

    Given previously normal levels, no routine screen would be carried out. While intake was suboptimal compared to EFSA AIs, there was an absence of any physical indication of deficiency; thus a conservative approach was taken and the patient would be monitored annually for physical or biochemical presentations of deficiency; change in hair colour or integrity (copper or selenium), or unexplained neutropenia with or without refractory anaemia unresponsive to iron (copper). 

    Discussion and learning

    Given expense and difficulty with interpretation, biochemical investigations should not be done indiscriminately. In the absence of guidelines, it is best to start with ‘routine’ tests, eg. iron studies. Proceed with additional tests only when biochemical, physical and intake data gives strong reason to do so. As illness/inflammation affects the metabolism of nutrients, it is best to do nutritional bloods when well. is a useful resource, but discuss with your testing laboratory regarding site-specific reference ranges and test availability. The Pediatric Nutrition-Focused Physical Exam Pocket Guide by the Academy of Nutrition & Dietetics is a useful guide for physical exam and interpretation. The BNF for children is useful for vitamin and mineral supplementation/prescription guidelines. 

    It is important to acknowledge the effect of any intervention on parents, the child and the family. Vitamin or mineral supplements can have side-effects and administration can cause further stress. Liquid preparations are often preferred. It is best to avoid asking parents to ‘hide’ supplements in food as this can illicit food refusal and negative effects on the parent-child dynamic. Alternative options such as fortified foods should be utilised where possible. 

    Micronutrient deficiency can occur with restricted diets. Thorough assessment by the RD should include intake and physical exam with supporting biochemical investigations as indicated. The RD’s role is essential to the interpretation and translation of this complex area of nutrition science. 

    Dónal Farrell is a freelance consultant dietitian with a special interest in paediatrics


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    2. Alliance IUN. National Pre-School Nutrition Survey Summary Report [Internet]. 2012 [cited 2019 Sep 26]. Available from:
    3. Ma NS, Thompson C, Weston S. Brief Report: Scurvy as a Manifestation of Food Selectivity in Children with Autism. J Autism Dev Disord [Internet]. 2016 Apr [cited 2019 Sep 26];46(4):1464–70. Available from:
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    © Medmedia Publications/Professional Nutrition and Dietetic Review 2019