Kirsty, who is 10 years old, comes to see you with her mother as she has been putting on a good deal of weight. They think the problem started 2 years ago, and she now weighs 80 kg and is 148 cm tall. She is in her last year at primary school and is by far the tallest girl in the class. She has been an excellent pupil to date and has happily gone to school in the past, but over the last term she has begun to refuse to go. She says that she does not like it anymore as children have started to tease her because of her weight.
Her mother, who is overweight herself, has been trying to encourage her to eat fruit and vegetables, and has also tried to encourage her to be more active, but Kirsty resists as she is ridiculed when she does so. Mrs Hare recognizes that Kirsty’s lifestyle is not ideal, but does not feel that it fully explains her weight problem. She is becoming convinced that Kirsty has a glandular problem.
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(a) You are sure that Kirsty does not have a hormonal or glandular cause for her obesity. How can you be so sure?
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Kirsty is tall for her age and also clearly has no learning disability. She therefore has ‘simple’ or nutritional obesity. Children with a genetic or syndromic cause for their obesity tend to be short, dysmorphic and have learning difficulties. Hormonal causes are rare, and children show poor growth in height as they put on weight.
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(b) What is important to ask about in the history?
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Even though you may not be looking for a cause for Kirsty’s obesity, it is important to take a good history. Asthma is more common in obese children and can contribute to a lack of exercise. Sleep apnoea is quite common and you should ask about snoring, cessation of breathing at night and lethargy during the day. A family history of obesity, adult-onset diabetes and cardiovascular disease is relevant.
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(c) What do you look for on physical examination?
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It is important to look for acanthosis nigricans—a dark velvety change in the skin in the neck, axillae and knuckles—as this indicates that she may well already have insulin resistance. Her blood pressure should also be checked.
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(d) Is it worthwhile doing any investigations?
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As it is so unlikely that Kirsty has a medical cause for her obesity it is unnecessary to carry out investigations to make a diagnosis. However, you might consider checking a fasting lipid screen, liver function tests and an oral glucose tolerance test as she is at high risk for co-morbidity.
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(e) Her mother asks you if you can reassure her that Kirsty simply has puppy fat. What do you say?
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Unfortunately you cannot reassure Kirsty and her mother that this is "puppy fat". She is at high risk of adult obesity, which is compounded by the family history. You can, however, tell her that if she can only hold her weight steady that she will slim down as she is only 10 and is likely to have a good deal more growth before she reaches adult height.
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(f) What help can you offer Kirsty?
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Kirsty needs help in changing her lifestyle. She needs to engage with someone who can encourage her to eat a balanced, healthy diet and be more active. Crash diets are to be discouraged as they tend to lead to a rebound in weight gain, and are potentially damaging in children.
