-SERUM PREGNANCY HORMONE TEST
-PROGESTERONE CHALLENGE TEST
-SERUM HORMONE PROFILE
-THYROID FUNCTION TEST
Following a detailed history and physical examination, investigations will be directed to confirm the suspected and possible cause of the HPO axis disorder. Below are some of the common investigations commonly done to unravel the causes of absent and irregular menses.
1. SERUM PREGNANCY HORMONE TEST
A serum pregnancy hormone test or simply a blood pregnancy test must be done in all sexually active women presenting with absent or delayed menses or with abnormal menstrual bleeding following a period of oligomenorrhea to exclude pregnancy, as pregnancy is the commonest cause of absent menses or amenorrhea in sexually active women. Even among women with irregular menstrual cycles or anovulatory cycles, an occasional ovulation may occur such that as long as they are exposed to unprotected intercourse, there remains a chance of pregnancy, no matter how unlikely.
2. PROGESTERONE CHALLENGE TEST
In all women with disorders of the HPO axis, PCOS is the commonest cause. It is also the only cause of absent or irregular menses, associated with high or normal levels of oestrogen hormone in the blood, contrary to all other causes of absent or irregular menses, in which there is a chronic state of low oestrogen level, referred to as a hypoestrogenic state. Therefore, women with PCOS presenting with amenorrhea or oligomenorrhea, will respond with vaginal bleeding within 2 days to 2 week of completion of a 7 to 10 days course of progesterone tablets, in contrast to women with low oestrogen blood level e.g. those with POF and chronic hyperprolactinaemia or women with genital tract outflow obstruction such as severe Asherman syndrome and cervical stenosis. Therefore the use of progesterone tablets in women presenting with oligo/amenorrhea in a bid to challenge the uterus to bleed is referred to as progesterone challenge test. While a positive test, seen as withdrawal bleeding few days to withdrawal of the given progesterone tablet signifies an intact endometrium with adequate oestrogen exposure, suggestive of PCOS, a negative result seen as failure of bleeding after withdrawal of the progesterone tablets signifies either a severe obstruction to the outflow of the blood from the uterus or an endometrial lining that has not been exposed to adequate oestrogen.
To further differentiate the above two possible causes of a negative progesterone challenge test result, a combined oral contraceptive pill (COCP) can be given to such women for a month to assess for a withdrawal bleeding or an HSG can be ordered, based on the suspected cause of the amenorrhea. In the event of a positive bleeding after the use of a complete cycle of COCP, then a chronic state of low oestrogen such as POF and chronic hyperprolactinaemia would be suspected, but in the event of a negative result, the presence of an obstruction to the out flow of menses would seem more likely.
3. SERUM HORMONE PROFILE
A hormone profile is usually indicated in all women with a disorder of the HPO axis. Usually done within the third to the fifth day of the menstrual cycle for all couples being worked up for infertility management, it can also be done on the third day of a withdrawal bleeding to help interpret the result similar to what is expected of a woman in the early phase of her menses. This is because women with irregular menses can not be easily timed at being at any particular phase of their menstrual cycle, yet an occasional ovulation can still occur. Hormones usually assayed or measured are the LH, FSH, testosterone, prolactin and oestrogen. A reversal of the normal FSH:LH ratio (normal is 2:1) and a high level of the LH hormone may suggest the presence of PCOS in women with oligo/amenorrhea. A high testosterone hormone level may also be seen in women with PCOS as well as women with CAH and other androgen secreting tumours. Other hormonal assays for other endocrinological causes of absent and irregular menses, should only be done in women where history and clinical presentation suggest so, e.g. the cortisol level in women suspected of Cushing’s syndrome.
4. THYROID FUNCTION TEST
A thyroid function test comprising of free thyroid hormones ( T3 and T4) and a TSH level should only be done in women where clinical features suggests a thyroid disorder, otherwise it is not routinely done.
5. IMAGING TESTS
1) TRANSVAGINAL SCAN (TVS)
A TVS can be used to view the general appearance of the ovaries and in the process help diagnose PCOS. Polycystic ovaries refers to the presence of multiple small cysts at least 12 or more each less than 1mm in diameter, in one or both ovaries. While many women with polycyctic ovaries may not have PCOS, similarly, many women with PCOS may have normal looking ovaries on TVS. Hence specific criteria are required to be met before a diagnosis of PCOS is made in any particular woman.
2) HSG AND HYSTEROSCOPY
Women with negative progesterone challenge test (PCT) result, suspected of having an obstruction along their femle genital tract to the outflow of their mesntrual period, can be investigated with imaging studies such as hysterosalpingography (HSG) or a hysteroscopy to confirm the diagnosis of a uterine synechiae.
3) MRI AND CT SCAN
MRI and CT scan can be used to view the skull in cases suspected of brain tumors either within the pituitary gland and or the hypothalamus. This is indicated in women who present with headache, visual disturbances and oligo/amenorrhea. Similalry, a large prolactin secreting tumor may be suspected if a very high prolactin level is reported in the hormone profile with or without local symptoms of compression of surrounding structures such as head ache or blurring of vision by the suspected prolactinoma.
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