In Marfan syndrome, from birth, children grow on or above the 99th percentile for their age and sex, and are usually one of the tallest in their class at school. In contrast, their average weight is 25th percentile, which gives them their tall, lanky look. When asked, adult males say that 6 foot 8 inches is the tallest they would like to be, since otherwise “they do not fit in this world”. Car and aeroplane seats are not comfortable, clothing and shoes are difficult to find, and tall women worry that they may not find a suitable mate.
How should a parent manage this common problem? It is best to keep a growth chart of the child’s height measured in bare feet, every year on the child’s birthday. When the child reaches 150 cm (59 inches) it is time to be seen by a paediatric endocrinologist, for prediction of final height. Basically, 30 cm is added to the child’s height, but to determine final height more accurately, a wrist x-ray for bone age, and pubertal staging through examination for signs such as early breast development, can refine this estimate.
If agreed with the daughter and parents, low dose sex steroid therapy taken orally can be used to induce puberty at an age and height judged to achieve a satisfactory end point. For example, if a girl is not to exceed a final height of 180 cm, she needs to have started breast development (spontaneously or induced with low dose oestrogen) when she has obtained a height of 150 cm. Exactly the same arithmetic applies to boys whose puberty can be induced with injections of low dose testosterone. Expected side effects need to be discussed and acceptable.
With hormone therapy, the long bones cease to grow, as confirmed by the wrist x-ray. This signals the end of the growth spurt.
In recent years females treated with high dose oestrogen have reported unacceptable side effects including cancer, and reduced fertility. Therefore, low doses of sex steroid are now recommended for purposes of safe treatment of tall stature.
In summary, parents can help by measuring the child’s height annually and taking these figures to the appointment when the child is referred at height 150 cm by the general practitioner to a paediatric endocrinologist who can supervise pubertal management safely.
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Growth-Reductive Therapy in Children with Marfan Syndrome. Rozendaal L; Le Cesse S., Wit J. M., Hennekam R. C. M., Dutch Marfan Working Group. The Journal of Pediatrics November 2005:674 - 679