Micropenis is an unusually small penis. The term micropenis (MP) is applied if the measured penile length is more than 2.5 standard deviations below the mean for age (Pic. 1). The condition is usually recognized shortly after birth. The term is most often used medically when the rest of the penis, scrotum, and perineum are without ambiguity, such as hypospadias. Micropenis occurs in about 0.6% of males.

Most cases are due to lack or decreased testosterone levels that can be secondary to lack of gonadotropins or testosterone deficiency or dysfunction. Micropenis can also occur as part of many genetic syndromes (such as Kallmann syndrome and Klinefelter syndrome). It is sometimes a sign of congenital growth-hormone deficiency.

Patients with micropenis have a low sperm count which results in infertility or decreased fertility. Micropenis has an effect on the psyche. Men often have low self-confidence and suffer from depression.

Some types of micropenis can be addressed with growth hormone or testosterone treatment in early childhood. Operations are also available to increase penis size in cases of micropenis in adults.

Klinefelter syndrome

Klinefelter's syndrome is a condition that occurs in men who have an extra X chromosome in most of their cells. The syndrome can affect different stages of physical, language and social development. The symptoms of having Klinefelter's Syndrome is having a small penis and small firm testicles. The existence of reduced penile size were evaluation in 16.7% and 11.5% of prepubertal and pubertal patients. 3.1% of infertile males have Klinefelter syndrome.

Kallmann syndrome

Kallmann syndrome (KS) is a rare genetic condition that is characterised by a failure to start or a failure to complete puberty. Patients with KS lack a surge of gonadotropin-releasing hormone (GnRH), luteinizing hormone (LH), and follicle-stimulating hormone (FSH) that occurs between birth and six months of age. This surge is particularly important in infant boys as it helps with testicular descent into the scrotum. A small percentage of boys with KS will be born with micropenis and/or undescended testes, both of which may be treated surgically in the first year of life.

Hypogonadotropic hypogonadism

Hypogonadotropic hypogonadism (HH), also known as secondary or central hypogonadism, as well as gonadotropin-releasing hormone deficiency or gonadotropin deficiency (GD), is a condition which is characterized by hypogonadism due to an impaired secretion of gonadotropins.

Normal pubertal development and reproductive function depends on the intact release and action of hypothalamic gonadotropin releasing hormone (GnRH). As a precondition, distinct developmental and functional procedures involving the coordinated action of other hypothalamic hormone-receptor systems are required for GnRH disposal.

Examples of symptoms of hypogonadism include delayed, reduced, or absent puberty, low libido, and infertility. Male patients may present at birth with micropenis and cryptorchidism and undetectable gonadotropin levels.


Azoospermia is the medical condition of a man not having any measurable level of sperm in his semen. Pretesticular azoospermia (an inadequate stimulation of otherwise normal testicles and genital tract)may be caused by Kallmann syndrome and other genetic conditions that lead to GnRH or gonadotropin deficiency. As mentioned above a small percentage of boys with KS will be born with a small penis, causing infertility. In humans, azoospermia affects about 1% of the male population and may be seen in up to 20% of male infertility situations.

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Azoospermia ―sourced from Wikipedia licensed under CC BY-SA 3.0
Klinefelter syndrome ―sourced from Wikipedia licensed under CC BY-SA 3.0
Kallmann syndrome ―sourced from World Heritage Encyclopedia licensed under CC BY-SA 3.0
Hypogonadotropic hypogonadism ―sourced from Wikipedia licensed under CC BY- SA 3.0
Early detection of fetal micropenis after IVF-ICSI ―by Bashiri et al. licensed under CC BY 3.0
Micropenis ―sourced from Wikipedia licensed under CC BY-SA 3.0
Human penis size ―sourced from Wikipedia licensed under CC BY-SA 3.0
Klinefelter's Syndrome ―sourced from Project-14 licensed under CC BY-SA 3.0
Flacid Micropenis ―by Torez2012 licensed under CC BY-SA 3.0
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