Boy’s Testosterone Levels

Author: Brian Hildebrandt, Last Updated: Dec 22, 2017

A reader asks…

Hi, my son is 9 yrs old.

While having his check up we mentioned to the doctor his penis shaft is a bit small.

He advised us to take a testosterone test and the boy’s testosterone levels check out to be 1.50 ng/dl.

Can you please tell whether the level is normal for a 9 year old boy?

Thanks in advance for your help.

Testosterone Ranges in Boys

According to the ranges I found it lists anything below 9ng/dl as normal for a 9 year old. Looking at the minimums for the age group above and below 9 year olds it lists the minimums as 2-3 ng/dl so your son may be a little on the low side.

I’m not extremely familiar with testosterone interactions in children, but in adults being on the low side of the range can still present symptoms. The ranges are developed by looking at where 95% of the population lies.

It’s based on a false assumption that 95% of the population is perfectly healthy, which isn’t always the case. Getting close to the bottom of the range may present symptoms of low T as well, however many doctors won’t acknowledge this.

Puberty and Penis Size

Once a boy hits puberty his penis size grows due to increased testosterone. This is mostly governed by the testosterone metabolite DHT (dihydrotestosterone) which causes the majority of androgenic features in males (body hair, lowered voice, acne, etc…)

After puberty, penis size is no longer influenced by DHT, so there is a critical window for growth to take place (11-17 years old). Otherwise you’d see adult men trying to increase their penis size this way, which unfortunately doesn’t work.

Most doctors won’t treat micro penis with testosterone/DHT until the later ages of puberty (13.5-17 years old).

Male Child, Teenager to Adult – Serum Total Testosterone

Premature (26-28 weeks): 59-125 ng/dl

Premature (31-35 weeks): 37-198 ng/dl

Newborn: 75-400 ng/dl

1-7 months: Levels decrease rapidly the first week to 20-50 ng/dl, and then increase to 60-400 ng/dl between 20-60 days. Boy’s testosterone levels then decline to prepubertal range levels of 3-10 ng/dl by seven months.

7-9 years: Less than 9 ng/dl

10-11 years: 2-57 ng/dl

12-13 years: 7-747 ng/dl

14-15 years: 33-585 ng/dl

16-17 years: 185-886 ng/dl

18-39 years: 300-1080 ng/dl

40-59 years: 300-890 ng/dl

60 years and older: 300-720 ng/dl

Androgen Deficiency May Cause Micro Phallus

“Androgen deficiency that develops early in childhood has few consequences, but if it occurs when puberty is expected, secondary sexual development is impaired.

Such patients have poor muscle development, a high-pitched voice, inadequate phallic and testicular growth, a small scrotum, sparse pubic and auxiliary hair, and absent body hair.

They may develop gynecomastia and grow to eunuchoidal body proportions (arm span exceeds height by 5 cm; pubic to floor length exceeds crown to pubic length by > 5 cm) because fusion of the epiphyses is delayed and long bone growth continues.”

Reference: Androgen Deficiency during 2nd and 3rd Trimesters may cause Micro Phallus.

Average Penis Growth Throughout Puberty

“The penis, measured in the stretched flaccid state, increases from an average length of 6.2 cm in pre-puberty to 12.4 +/- 2.7 cm in white adults and to 14.6 cm in black and 10.6 cm in Asian men”

“Penis growth at puberty generally starts between the ages of 11-14.5 and finishes between the ages 13-17.5”


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