Let's go on to
This clinical syndrome results from failure of the
testes to produce physiologic levels of testosterone
and normal numbers of sperm due to disruption of
the hypothalamc and pituitary testicular axis.
It can be primary, in the case
of testicular abnormalities
or secondary in the case of pituitary dysfunction
where GnRH and FSH and LH are deficient.
Causes of hypogonadism are numerous and
are divided into primary and secondary.
Primary would primarily affect the testicles and secondary
would be another cause, usually of the endocrine axis.
Dealing with the primary cause is infection such
as mumps which is a viral infection with orchitis
which is inflammation of the testicles,
is a significant cause of hypogonadism.
It can also be a consequence of radiation treatments for
conditions like testicular malignancies or lymphomas.
It can also occur when taking
chemotherapy agents or other toxins.
When there is being testicular
trauma or testicular torsion,
and then in Klinefelter syndrome which is 47,XXY
tends to be the most common congenital cause.
Under these situations, you would look for
the following clinical characteristics:
Very tall stature, small
testes, developmental delay
and patients manifesting socialization
and other psychological abnormalities.
Moving on to secondary
Kallman syndrome, which is associated
with anosmia is a pituitary cause.
Also, hyperprolactinemia, medications that
affect secretion of GnRH or FSH and LH
Critical illness, untreated sleep disorders
which usually manifest as central sleep apnea,
Obesity which can also contribute
not only to the condition a priori
but also through sleep disorders
and central sleep apnea.
Liver and kidney diseases, alcohol
and marijuana use, eating disorders
and finally, trauma, this time to the
head as opposed to the testicles.
Let's go on to a
case that overviews
a 45 year old man, who is evaluated for the
management of tiredness and reduced libido,
a very common presentation
in general medical practice.
Medical history is significant for
hypertension and hyperlipidemia.
Medications are hydrochlorothiazide
On physical exam, his
vital signs are normal.
He has normal hair distribution, no gynecomastia
and an unremarkable testicular exam.
Lab studies obtained at 6 PM revealed a total
testosterone level of 210 ng/dL
and an LH level of 5 mU/mL
What should one do next?
So, going through this case, the low libido and fatigue
suggest that the patient has a low testosterone level.
A testosterone level should be checked
at 8 AM, the diagnosis is then confirmed
if he has two separate measurements
at 8 AM that are both low.
This particular patient did indeed
have a low testosterone level
and a low luteinizing hormone
level at 5 mU/mL
In the setting of low libido implying
that he has secondary hypogonadism.
Measuring at 8 AM testosterone level is indicated
in men with symptoms of hypogonadism.
If the testosterone level is low, a second level
is then checked the following day, again at 8 AM.
The diagnosis is made with a low
serum testosterone measurements.
Measurements of free testosterone
is appropriate in obese men
because obesity will lower the
sex hormone binding globulin
and will lead to falsy low measured
total testosterone levels.
If the testosterone is low, a serum
luteinizing hormone is then measured.
If this is elevated, primary
hypogonadism is the diagnosis.
If the luteinizing hormone level is low, then
it would suggest secondary hypogonadism.
Further evaluations of these patients
is usually directed to identifying
the cause of the elevation or
decrease in luteinizing hormone.
Treating hypogonadism is usually in
the form of a testosterone therapy
which can be initiated after the
etiology has been determined.
The goal is to replace testosterone so that the measured
total testosterone value is in the mid to normal range.
Testosterone replacement should be in the form of a
gel, a patch or an injection to avoid the phenomenon
whereby testosterone that's taken orally is heavily
metabolized by the liver during first pass.
Testosterone therapy have
clinical benefits that include
an increase in libido, an increase in
lean muscle mass and fat free mass
and also in bone density and improvement
in secondary sexual characteristics.
Potential adverse effects include
acne, their impact to the prostate,
so they should be avoided in patients who
have a history of prostatic carcinoma,
also in patients who have a history of obstructive sleep
apnea and then hematologic effects are significant.
Patients tend to develop an increase in their red
cell volume, otherwise known as erythrocytosis
and they can also have an increase in
their platelets or thrombophillia.
The thrombophillia can lead to
the occurrence of blood clots
and the thrombocytosis may
contribute to sluggish circulation.
Patients should be counseled on the decreased fertility
that's associated with exogenous testosterone therapy.
Testosterone therapy is only indicated for
the treatment of testosterone defficiency.
It is not used for
So if the patient
it is a good idea for them to know this
prior to taking testosterone replacement.