Adolescent girls with the eating disorder anorexia nervosa may reach normal height once they recover from the disease, new research suggests.

However, growth may be permanently stunted in girls who suffer from anorexia for longer than about 2.5 years, according to the research conducted by Dr. Rajani Prabhakaran of Harvard Medical School in Boston and colleagues.

Studies on the impact of anorexia on growth and stature have yielded mixed results. While anorexia might be expected to cause short stature, and some studies suggest that girls with the eating disorder are indeed shorter than normal, other research suggests they may reach their full height potential, or even be taller than average.

During normal puberty, levels of growth hormone (GH) and insulin-like growth factor-1 (IGF-1) rise, triggering a growth spurt, Prabhakaran and colleagues explain in the journal Pediatrics. Growth slows and eventually stops as estrogen levels rise. It’s possible, they say, that this process of growth and bone aging is delayed in girls with anorexia, giving them a chance to reach their full potential height after they recover.

To investigate, the researchers looked at 110 12- to 18-year-old girls with anorexia and 98 healthy controls of the same age. They followed a subset of both groups for a year, and also tested hormone levels over a 12-hour period in some of them. They estimated the girls’ potential adult height based on the heights of their parents.

They found that girls with anorexia had lower levels of IGF-1 than the healthy girls, although most had levels of the hormone within the normal range. They had relatively high levels of GH, suggesting that they had become resistant to this hormone’s effects.

Girls with the lowest IGF-1 levels and those with anorexia for the longest period of time were the shortest. And while GH levels predicted height in the healthy girls, GH levels weren’t related to height in the girls with anorexia, suggesting that the hormone didn’t influence bone growth in girls with the condition.

Girls who had been sick for 32 months or longer were shorter than average, while those who had the condition for at least 29.5 months had a lower-than-average predicted adult heights.

Among girls with anorexia who hadn’t yet reached puberty, a greater delay in bone aging was linked to faster growth during follow-up.

“It is possible that previous reports of short stature with anorexia were from studies in children with a prolonged duration of anorexia and delayed diagnosis,” the researchers say. “In such situations, a delay in bone aging may not be sufficient to protect against statural deficits that arise from very low and sustained IGF-1 levels consequent to severe and prolonged undernutrition.”

They call for long-term, larger studies to further investigate whether girls with more severe anorexia and those who have had the condition for a longer time are indeed at greater risk of stunted growth.

SOURCE: Pediatrics, June 2008.