Editing Testosterone Deficiency (2018) (section)

==== Initial Evaluation ====
* '''<span style="color:#ff0000">Serum luteinizing hormone (LH)</span>'''
**'''<span style="color:#ff0000">Should be measured in all patients with low testosterone</span>'''
*** '''Low or low/normal LH level is consistent with a secondary (central) hypothalamic-pituitary defect, (hypogonadotropic hypogonadism)'''
***'''High LH indicates a primary testicular defect (hypergonadotropic hypogonadism)'''
**** In some cases, the etiology is obvious (e.g. iatrogenic causes), in others, a karyotype may be warranted to establish a diagnosis of Klinefelter syndrome (47, XXY). In other cases, it may not be possible to establish a definitive etiology
***** '''Klinefelter syndrome'''
****** '''See [https://test.urologyschool.com/index.php/Disorders_of_Sexual_Differentiation#Klinefelter_syndrome Klinefelter Syndrome Section] in [[Disorders of Sexual Differentiation]] Chapter Notes'''
******'''Characterized by hypergonadotropic hypogonadism (very high LH and FSH, low testosterone)'''
****** '''Management'''
*******'''Exogenous testosterone to treat signs and symptoms associated with low testosterone'''
*** '''<span style="color:#ff0000">Age-related changes</span>'''
**** '''<span style="color:#ff0000">LH does not decline as males age</span>, suggesting that reduced testosterone results from testicular hypofunction rather than changes at the hypothalamic-pituitary levels.'''
**** '''<span style="color:#ff0000">The number of Leydig cells per testis has been shown to remain unchanged,</span> suggesting that changes in the steroidogenic machinery of the individual cells and not their reduced number are responsible for the declining serum testosterone concentrations.'''
* '''<span style="color:#ff0000">Serum prolactin</span>''' 
**'''<span style="color:#ff0000">Should be measured in patients with low testosterone levels AND low or low/normal luteinizing hormone levels (hypogonadotropic hypogonadism) to screen for hyperprolactinemia.</span>'''
** '''<span style="color:#ff0000">Hyperprolactinemia</span>''' 
***Prolactin is a hormone that is synthesized and secreted from the pituitary gland
***'''<span style="color:#ff0000">Cause of secondary (central) testosterone deficiency and can lead to (4):</span>'''
***# '''<span style="color:#ff0000">Infertility</span>'''
***# '''<span style="color:#ff0000">Decreased libido</span>'''
***# '''<span style="color:#ff0000">Sexual dysfunction</span>'''
***# '''<span style="color:#ff0000">Gynecomastia</span>'''
*** '''<span style="color:#ff0000">The mechanism of action of prolactin may be through inhibition of dopaminergic activity in the medial preoptic area and decreased testosterone.</span> In addition, prolactin may have a direct effect on the penis through its contractile effect on the cavernous smooth muscle'''
*** '''<span style="color:#ff0000">Causes:[https://pubmed.ncbi.nlm.nih.gov/33295257/ §]</span>'''
***# '''<span style="color:#ff0000">Medications (7):</span>'''
***## '''<span style="color:#ff0000">Dopamine antagonists (most commonly)</span>'''
***## '''<span style="color:#ff0000">Anti-psychotics</span>'''
***## '''<span style="color:#ff0000">Selective serotonin reuptake inhibitors</span>'''
***## '''<span style="color:#ff0000">Proton pump inhibitors</span>'''
***## '''<span style="color:#ff0000">Calcium channel blockers</span>'''
***## '''<span style="color:#ff0000">Anti-emetics</span>'''
***## '''<span style="color:#ff0000">Opiates</span>'''
***# '''<span style="color:#ff0000">Chronic medical conditions (3):</span>'''
***## '''<span style="color:#ff0000">Hypothyroidism</span>'''
***## '''<span style="color:#ff0000">Renal failure</span>'''
***## '''<span style="color:#ff0000">Cirrhosis</span>'''
***##'''<span style="color:#ff0000">Stress</span>'''
***# '''<span style="color:#ff0000">Tumors</span>'''
***##'''<span style="color:#ff0000">Pituitary tumor</span>'''
***##* Persistently elevated prolactin levels can indicate the presence of pituitary tumors such as prolactinomas. '''<span style="color:#ff0000">Pituitary prolactinomas are benign tumors that can be effectively managed using medications, such as bromocriptine or carbergoline</span>'''
***##'''<span style="color:#ff0000">Prolactin producing tumors</span>'''
***##Non-lactotroph adenomas (GH, ACTH, chromophobe)
***##Cystic adenomas
***##Tumors near the hypothalamus or pituitary that interfere with the secretion of dopamine or its delivery to the hypothalamus (e.g.,craniopharyngiomas) infiltrative diseases (e.g., sarcoidosis, hemochromatosis, TB), and malignant tumors that arise within or near the sella or metastasize to these areas
***#Other
***##Elevated estrogen levels
***##Chest wall injuries
*** '''<span style="color:#ff0000">Diagnosis and Evaluation</span>'''
****'''<span style="color:#ff0000">If prolactin is mildly elevated (≤1.5 times the upper limit of normal), a repeat fasting prolactin should be drawn to rule out a spurious elevation[https://pubmed.ncbi.nlm.nih.gov/33295257/ ★]</span>'''
***** '''<span style="color:#ff0000">False positive elevated prolactin levels can occur with a stressful blood draw.</span> Consider this if it is only slightly elevated'''
**** '''For persistently elevated prolactin levels above the normal value without an exogenous etiology, MRI is indicated.[https://pubmed.ncbi.nlm.nih.gov/33295257/ ★]'''
****'''<span style="color:#ff0000">If total testosterone levels <150 ng/dL with a low or low/normal LH, patients should undergo a pituitary MRI regardless of prolactin levels, as non-secreting adenomas may be identified.</span>'''
**** '''Patients should be referred to an endocrinologist for further evaluation if the etiology for hyperprolactinemia cannot be established.'''
***'''Management<span style="color:#ff0000">[https://pubmed.ncbi.nlm.nih.gov/33295257/ §][https://www.ncbi.nlm.nih.gov/books/NBK459347/ §]</span>'''
****'''Depends on the etiology of the hyperprolactinemia'''
****'''If pituitary prolactinoma'''
*****'''Options (2):'''
******'''Dopamine agonists (first-line)'''
******'''Transsphenoidal surgery''' 
*******'''Surgery may be considered when dopamine agonist treatment is unsuccessful or if the patient prefers surgery to life-long therapy'''
****If hyperprolactinemia without, management should focus on treatment of the underlying condition or factor causing the elevated prolactin (e.g., treatment of hypothyroidism, medication changes for drugs associated with elevated prolactin levels).