Endocrine Evaluation
Basic endocrine evaluation includes measurement of
# Serum testosterone (T)
# Follicle-stimulating hormone (FSH)
Testosterone is necessary for the development and maintenance of secondary sexual characteristics and libido as well as initiation and maintenance of sperrnatogenesis. Serum FSH crudely reflects the status of the serniniferous epithelium. Elevated serum FSH results from impaired secretion of inhibin, a Sertoli cell product that normal feeds back at the pituity and hypothalamus to turn off FSH secretion and suggests abnormalities in the seminiferous epithelium and subsequently spermatogenesis. An FSH level greater than two to three times the upper limits of normal suggests severely impaired seminiferous tubule , but may still be treatable.
# Luteinizing hormone (LH)
is stimulatory to the Leydig cells and hence T production. Isolated LH abnormalities are very rare. LH levels need be obtained only in men with abnormal T levels .Low levels of FSH, LH, and T are diagnostic of hypogonadotropic hypogonadism. These men have a delay or failure in the onset of puberty and therefore poorly developed secondary sexual characteristics and small firm testes. Testosterone replacement will masculinize these men but testicular growth and the initiation of spermatogenesis requires gonadotropin replacement. Hypogonadotropic hypogonadism is usually due to a pituitary tumor, with the most common pituitary lesion being a benign prolactinoma. These are usually associated with a decreased libido, an elevated serum prolactin level, and decreased serum T and LH levels. Both macro and microadenomas are often best treated with bromocriptine. Serum estrogens, prolactin, and adrenal steroids are only measured if clinically indicated (low serum T, decreased libido, gynecomastia, or a history of precocious puberty).
Men who are incompletely masculinized have disproportionately long extremities due to absent or deficient androgen stimulation required for epiphyseal closure at the time of puberty. This is seen in men with hypogonadotropic hypogonadism (Kallmann's syndrome when associated with absent sense of smell or other midline defects) or Kleinfelter's syndrome. After evaluation of body habitus, the thyroid is palpated and the heart and lungs auscultated. Chronic bronchitis associated with congenital epididymal dysplasia is seen in Young's syndrome. Situs inversus with associated immotile sperm is seen in immotile cilia (Kartagener's) syndrome. The breasts are observed and palpated for gynecomastia, which can be associated with estrogen secreting testicular neoplasms, adrenal tumors, and liver disease. Nipple discharge or tenderness may be seen with prolactin-secreting pituitary adenomas.
The abdomen is palpated and percussed. A large varicocele that does not collapse in the supine position warrants a search for an abdominal mass. An enlarged liver suggests hepatic dysfunction, which may be associated with infertility due to altered sex steroid metabolism. The penis and urethral meatus is examined for condylomata. The urethra is milked for discharge. The location of the meatus is noted. Severe hypospadias may result in inadequate delivery of semen into the vagina. Scrotal examination is first performed with the patient supine. This allows a varicocele, if present, to collapse; testis size and consistency can then be properly assessed. Use an orchidometer to measure testicular size. Normal testicular volume ranges from 15 to 30 cm . The testes should be firm in consistency. A change in testicular consistency is indicative of testicular pathology. Small soft testes indicate poor spermatogenesis. Small hard testes suggest postorchitis or posttorsion atrophy or Kleinfelter's syndrome.
Focal irregularities in consistency raise the suspicion of malignancy. Smooth firm nodules palpated on the surface of the testis usually represent tunica albuginea cysts. Mobile small hard bodies,corpora amylacea, may be palpated floating within the tunica vaginalis. Transillumination of the scrotum in a darkened room differentiates solid from cystic masses. In general, testes that are normal in size and-consistency usually have normal sperm production, whereas small-volume, soft testes are associated with impaired spermatogenesis. The normal epididymis, posterolateral to the testes, is soft and barely palpable. Induration, modularity, or irregularities are suggestive of epididymal pathology. A full, firm, easily outlined epididymis that is nontendcr suggests epididymal obstruction. Epididymal cysts or spcruiutoccies are firm, smooth, transilluminate, and almost always located in the caput.
The vas deferens should be palpated bilaterally. The vas is the diameter and consistency of a venetian blind cord, and is usually posteromedial and separate from the internal spermatic cord structures. We have observed bilateral congenital absence of the vas deferens (CAV) in 1.3% of of patients presenting for infertility evaluation. With a relaxed scrotum, the diagnosis of CAV can almost always be made by palpation. These men will have azoospermia associated with low seminal volumes and nonclotting clear ejaculate. Serum follicle-stimulating hormone (FSH) is usually normal, reflecting normal spermatogenesis. Testes biopsy and scrotal exploration are not necessary prior to therapy. Because the vas deferens derives from the ureteral bud, CAV is associated with. an 11% incidence of renal agenesis and abnormalities. A renal sonogram should be obtained in all men with CAV. Most men with CAV test positive for cystic fibrosis gene mutations, although they do not have any pulmonary manifestations of this disease.We test the patient and their wives for cystic fibrosis (CFTR) gene mutations and refer the couples for genetic counseling. Men with cystic fibrosis (CFTR mutations in association with digestive and/or pulmonary problems) will often have bilateral congenital absence of the vas deferens. CAV, whether associated with cystic fibrosis or not, may be treated using sperm retrieval and in vitro fertilization to effect pregnancies.
Large varicoceles are readily seen through the relaxed scrotal skin in a warm room with the patient standing. Small varicoceles may be appreciated as a distinct impulse and palpable dilation of the internal spermatic veins during the Valsalva maneuver. The best method to elicit a strong and sustained Valsalva is to tell the patient to bear down as if having a bowel movement. If a varicocele is detected, the patient should be placed supine. A varicocele should completely collapse when the patient is supine. A large varicocele, which does not collapse in the supine position, leads to suspicion of a retroperitoneal mass and an abdominal sonogram is indicated. In the hands of an experienced sonographer scrotal ultrasound with color flow Doppler is useful in the evaluation of questionable varicoceles, especially in obese men or men with a small tight scrotum. Our monographic criteria for the diagnosis of a varicocele is the presence of any internal spermatic veins greater than 3 mm in diameter associated with retrograde flow on Valsalva. Subclinical or questionable varicoceles are of limited clinical interest. Our data has clearly shown that response to varicoceletomy is related to varicocele size. Men with large varicoceles sustain a greater improvement in semen quality following varicocele surgery than men with small or subclinical varicoceles. Digital rectal examination is always performed. The size and consistency of the prostate is noted. Masses, cysts, irregularities, tenderness, and whether or not the seminal vesicles are palpable are noted. Stool should be tested for occult blood
Anatomy and Physiology of Male Reproduction
|
|
|
|