The study, published in Clinical Endocrinology (2004;60:682-7), stated that taking a supplement of vitamin A and iron can help children with constitutional delay of growth and puberty (CDGP).
The researchers compared the effect of supplementation with hormonal therapy on 102 boys with CDGP. The average age of the participants was 14.4 years - none of them showed any signs of puberty and all were short for their age and had a slow growth rate.
The boys were assigned to receive one of six treatments: 5 mg per day of a growth-promoting steroid hormone (oxandrolone) for six months; 100 mg of testosterone per month for three months; 100 mg of testosterone per month for six months; 6,000 IU of vitamin A per week plus 12 mg of iron per day for 12 months; 5 mg of oxandrolone per day for six months plus 6,000 IU vitamin A per week and 12 mg iron per day for 12 months; or no treatment.
The success of the different regimes was assessed by measuring at the beginning of the study and then at six and 12 months, the height, weight, pubertal status (by testicular volume), and bone age - namely the age based on the appearance of the bones as bone age is younger than a child's actual age in sufferers of CDGP.
The researchers found that those who were treated with vitamin A and iron had significantly faster growth rates than those in the control group. The growth rates in the vitamin A and iron group were similar to those seen in the testosterone and oxandrolone groups. The vitamin A and iron group was the only group to experience an increase in testicular volume - indicating the onset of puberty - after six months of treatment. All of the treatment groups had an increase in testicular volume at the end of 12 months, except the group that did not undergo any treatment.
The researchers therefore concluded that daily supplementation with small amounts of vitamin A and iron may be as effective as hormone therapy for boys with CDGP, without the same side-effect risks.
Vitamin A levels are lower in children with CDGP than in children of normal height and sexual maturity. Scientists have suggested that a deficiency of vitamin A may contribute to a delay in the onset of puberty by decreasing the secretion of growth hormone, leading to slowed growth. Iron is also necessary for normal growth, and it enhances the effect of vitamin A in the treatment of certain conditions.
CDGP restricts growth and delays the onset of puberty in boys and less frequently in girls. It is characterised by slow growth until the age of three, followed by normal growth until the time when puberty would normally begin, around the age of 12. Because puberty is delayed, normal testes enlargement does not occur in boys with CDGP and the growth of the skeleton is affected, causing improper bone development that can lead to sufferers being more prone to fractures later in life.
Children affected by CDGP eventually enter puberty and reach normal adult height, but the stigma of being short and sexually immature and the possibility of poor bone formation often leads doctors to prescribe sex hormones to induce puberty and enhance growth in such children.
Sex hormones can have a whole range of potential side effects including acne, muscle cramps, and perhaps most worryingly severe liver disease in cases of prolonged use.