Puberty Delay in boys: Explained

Normally, puberty in girls can start anytime between 8-14 years and in boys between 9-15 years. In most boys, the first changes of puberty begin around the age of 12 years. The earliest change is an increase in the size of the testicles. The penis starts to get bigger and pubic hairs start to grow. The growth spurt begins a little later, usually around the age of 14 years and it continues for the next 4-5 years.

Definition of delayed puberty

Because of the wide variation in the age at which puberty starts, the definition of delayed puberty is based on a statistical measure of age by which 95% of the population would have the onset of puberty. Due to changing lifestyles, the age at which puberty starts is on the downtrend across the globe.

The most commonly used definition for delayed puberty is a lack of any puberty change by 13 years in girls and 14 years in boys.

Puberty Delay in boys: Explained

What are the causes for delayed puberty in boys?

 In most boys with delayed puberty, the reason is that their body constitution is set for a late onset of puberty and this condition is known as constitutional delayed puberty. They are late bloomers, who eventually will have puberty and all the normal bodily changes associated with puberty.The boys with constitutional delayed puberty are born with a small penis. Otherwise, these boys are healthy and do not have any medical conditions or deficiencies. It is considered to be inherited through genes and most of these boys (50 to 75%), had parents with delayed puberty.

The remaining have delayed puberty due to one of these reasons:

  • Hypogonadotropic hypogonadism: Disorder in the brain (hypothalamus or pituitary gland) that results in low levels of puberty hormones, Follicle stimulating hormone (FSH) and  Luteinizing hormone (LH). The boys born with this condition may have a penis which is small in size.  Some boys have additional symptom of poor sense of smell, along with the delayed puberty (this combination of signs is called Kallmann syndrome)
  • Functional hypogonadotropic hypogonadism: Some boys who are suffering from chronic diseases (such as sickle-cell disease, inflammatory bowel disease, diabetes, cystic fibrosis, etc.) may have delayed puberty due to delay in the maturation of the pathways needed to activate the puberty process.
  • Hypergonadotrophic hypogonadism: Here there is a failure of testes resulting in low testosterone levels. These boys when physically examined, may have small testicles or sometimes have undescended testicles that are stuck in the abdomen. In others, the damage may be to any disease, injury, surgery or treatment (such as cancer treatments) that can cause damage to the testes.

What are the symptoms and signs of delayed puberty in boys?

Not developing any of the puberty related changes by the age of 14 years in boys should prompt the suspicion of delayed puberty.

The penis and testicles do not show any signs of growing even at the age of 14 years. Sometimes, the testicles have started to grow but penis remains small, which may indicate that the other features of puberty may begin in 6-12 months.

The boys who have constitutional delayed puberty will be shorter when compared to other boys of the same age. However, they will usually catch up with other boys by the time they are 18.

How is the diagnosis of delayed puberty made? 

  • Physical examination may offer the doctor clues about non-development of sexual characteristics in the affected subject. The penis and testicles may be examined to see if there are any defects such as undescended testicles.
  • Blood tests will be done to check the levels of Testosterone, Luteinizing hormone (LH), and Follicle stimulating hormone (FSH).
  • Sometimes, they may take an X-ray of bones to see the level of bone maturity (known as bone age x-ray).
  • Brain MRI may be done to investigate for problems with the pituitary gland.

How is delayed puberty in boys treated?

In boys who have constitutional delayed puberty, the doctor will try to reassure the parents to wait for puberty to start naturally. If the child is worried or depressed, counselling may be required to help the child cope.

In those who are impatient to wait for this, a short course of testosterone treatment may be prescribed to trigger the start of puberty. The dose and duration of testosterone injection therapy will be decided by the treating specialist (paediatric endocrinologist), but commonly it will be monthly injections given for many months. This will initiate the pubertal changes and promote the growth of the penis, pubic hair and other sexual characteristics, which will continue naturally after stopping treatment in most subjects.

In boys who have delayed puberty due to causes in the brain or testicles, testosterone administration is the treatment of choice, but they will require higher doses and this treatment will be required to be continued long-term.

Consult a top General Physician

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  • Traggiai C, Stanhope R. Delayed puberty. Best Pract Res Clin Endocrinol Metab. 2002 Mar;16(1):139-51.
  • Palmert MR, Dunkel L. Clinical practice. Delayed puberty. N Engl J Med. 2012 Feb 2;366(5):443-53.
  • Robert L. Rosenfield. Diagnosis and Management of Delayed Puberty. The Journal of Clinical Endocrinology & Metabolism 1990 70:3, 559-562.
  • American Academy of Pediatrics. Delayed Puberty in Boys: Information for Parents. Accessed at https://www.healthychildren.org/English/ages-stages/gradeschool/puberty/Pages/Delayed-Puberty.aspx
  • Australasian Paediatric Endocrine Group. Hormones and Me – Delayed Puberty. Accessed at http://www.apeg.org.au/Portals/0/Resources/Hormones_and_Me_6_Delayed_Puberty.pdf

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