الاثنين، 8 فبراير 2010

Gonads and Infertility

Gonads and Infertility


Investigations of male hypogonadism and infertility:
1- Semen analysis should be performed. Normal seminogram on two separate occasions requires no further endocrine functions testing.
2- Low sperm count necessitates measurements of plasma FSH, LH testosterone and prolactin.
a) Cases with primary (testicular, hypergonadotophic) hypogonadism show low plasma testosterone levels with increased FSH and LH.
b) Cases with secondary (pituitary - hypothalamic hypogonadotrophic) hypogonadism show reduction of plasma testosterone and selective reduction of FSH, LH or both.
Injection of human chorionic gonadotrophin corrects secondary hypogonadism.
Investigations for female subfertility:
1- In patients with normal menstruation: Serum progesterone should be determined daily between days 19 and 23 of the cycle. Values more than 30 nmol/L indicate ovulatory cycle, those between 10 and 30 nmol/L suggest ovulatory cycle with luteal phase defect, while values below 10 nmol/L indicate anovulatory cycle.
2- In patients with amenorrhea or anovulatory cycle, it is important to measure plasma levels of prolactin, FSH, LH, estradiol and sometimes TSH and free T4.
- If prolactin level is high: specific therapy with bromocriptine is started.
- If prolactin is normal: measure FSH, LH and estradiol. When FSH and LH are high and estradiol is low, there is primary ovarian failure. When LH is high with low FSH and oestradiol, the patient may have the polycystic ovary syndrome (PCOS). When all hormonal values are low, there may be hypothalamic, pituitary or other endocrine disease.

Some laboratory aspects of pregnancy
The clinical laboratory has an important role in diagnosis, management and evaluation of pregnancy, both normal and abnormal.
Diagnosis of pregnancy and ectopic pregnancy: The diagnosis of pregnancy is based on the detection of hCG in serum about 10 days after conception, with a marked and gradual increase thereafter. In ectopic pregnancy plasma hCG fails to rise at the normal rate.
Maternal serum screening for fetal defects: Prenatal diagnosis of fetal abnormalities is advised for pregnancies at risk because of either advanced maternal age or family history.
Maternal serum a-fetoprotein (AFP) is used to screen for neural tube defects (anencephaly and spina bifida) at 18-20 week gestation. If elevated levels are found on two occasions, ultrasound and amniocentesis may be indicated.
Screening for the presence of a fetus with Down’s syndrome can be performed using measurement of the following analytes in maternal serum at 16 wk gestation:
* AFP: values are approximately 30% lower in mothers having trisomy 21 or trisomy 18.
* Chorionic gonadotropin: values are approximalety 2 times higher when fetal Down syndrome is present.
* Unconjugated Estriol: values are approximately 0.7 time lower when fetal Down syndrome is present.
* Values of these analytes (triple markers) should be compared to median values reported for women of matched age, body weight and gestational age in weeks.

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