Book Review

When Puberty is Precocious: Scientific and Clinical Aspects

N Engl J Med 2007; 357:2413-2414December 6, 2007

Article

When Puberty is Precocious: Scientific and Clinical Aspects
(Contemporary Endocrinology.) Edited by Ora H. Pescovitz and Emily C. Walvoord. 468 pp., illustrated. Totowa, NJ, Humana Press, 2007. $139. ISBN: 978-1-58829-742-6

Kids grow up too fast these days — many parents, grandparents, and educators have voiced this sentiment, but is it true? When Puberty Is Precocious cogently presents both facts and speculations about whether children today are entering puberty earlier than children did in the past. Although the focus is on precocious puberty, the book is much broader in scope. The authors include many experts in clinical research and basic science. They eloquently address what is known about puberty and the problems that remain to be solved. What controls puberty? When is the onset of puberty too early? Why is it sometimes disordered? Within the book there is some repetition of concepts, which is not cumbersome but is actually helpful as the tangled story unfolds.

The book is divided into seven logical parts, but three current themes run through it. The first theme is the complex molecular mechanisms and neuroendocrine discoveries that are related to pubertal control. The pubertal reawakening of the hypothalamic gonadotropin-releasing hormone pulse generator is still a mystery, but the characters involved include neuropeptide Y as well as the γ-aminobutyric acid neurotransmitters and the glutamatergic and kisspeptin neurons. The discussion is thoughtful and covers a range of topics including rodent models, nonhuman primates, humans, and the exploration of candidate genes, setting the stage for readers to gain an understanding of the complexity of pubertal development.

The second theme in the book is the ongoing debate about historical trends and the intriguing influences on altered timing of puberty. Puberty is brought on by a complex combination of genetics, hormones, and environment. Various factors are discussed, including environment, endocrine disruptors, obesity, in utero effects, and economics. The question of what is normal versus what is abnormal is also woven throughout the book, and the old battle of nature versus nurture is visited. Although some contend that 50 to 80% of variation in the onset of puberty is genetic, others contend that environment plays a critical role not only because of the effect it has on endocrine disruptors but also because of its cultural and economic influences.

Endocrine disruptors are chemicals that disturb normal hormonal function, and their role in puberty is controversial. Plant estrogens, pesticides, and other agents have been implicated in some epidemics of early puberty, but the connection between these chemicals and puberty has not been proved. Obesity is a factor not only in the risk of cardiovascular disease and diabetes among adults but also in the early onset of puberty and pubertal disorders. But which is the chicken and which is the egg? Does increased body mass lead to early puberty or is it the result of early puberty — and why? In Chapter 5, “Puberty Is Starting Earlier in the 21st Century,” the author makes an argument for why puberty is beginning earlier than it did in “the good old days.” In Chapter 7, “Puberty Timing Remains Unchanged,” the authors present evidence for why things are not so different from the way they used to be. This discrepancy is helpful in illustrating the unknowns in this area of study. Part of this debate involves distinguishing between documentation about the onset of puberty, descriptions of pubertal progression, and data regarding the conclusion of puberty.

The third major theme is the comprehensive discussion of pathology — the true abnormalities in contrast to normal trends. Puberty can be delayed, precocious, absent, or reversed. One chapter is devoted completely to the psychosocial ramifications of precocious puberty. The causes of sexual precocity are thoroughly evaluated and range from the intriguing area of in utero influences, to known hormonal alterations in the ovaries, testes, pituitary gland, and hypothalamus gland, to speculations about children who were adopted from developing countries.

The tension between early puberty as a normal phenomenon and true precocious puberty, which compels investigation and treatment, should not be lost in the midst of all the other discussion in this book. I would emphasize the importance of not defining “normal” before we have a better understanding of the trends. Some girls may simply be early bloomers, whereas others the same age may have pubertal disorder.

A weakness of the book is the suboptimal quality of some of the reproduced illustrations. However, the book reads well and is organized in a way that makes it a valuable reference tool, and the references cited in the chapters are extensive. When Puberty Is Precocious will be appreciated by primary care physicians as well as pediatric endocrinologists. The open discussion of the unknown in the context of well-grounded science leaves the reader anticipating what the future will reveal. At the same time, practical answers for the care of patients and up-to-date changes in management are provided.

Karen O. Klein, M.D.
University of California, San Diego, San Diego, CA 92123
koklein@sbcglobal.net