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* nbme1-26-27
 #426534  
  tranquilizer - 07/09/09 15:42
 
  A 17‐year‐old girl is brought to the health center by her mother because the girl has had only two menstrual periods in the past 8 months. She had regular menstrual periods from menarche at age 14 years until 18 months ago. For the past 18 months she has been training as a long‐distance runner. Item 1 of 2 26. The underlying mechanism of her menstrual dysfunction is best defined by an abnormality in which of the following serum concentrations?
A ) Androstenedione
B ) Creatine kinase
C ) Luteinizing hormone
D ) Testosterone
E ) Thyroid‐stimulating hormone (TSH)


Which of the following is the most likely cause of the menstrual irregularity?
A) High‐carbohydrate diet
B ) Increased basal body temperature
C ) Increased muscle mass
D ) Loss of body fat
E ) Repeated volume depletion
 
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* Re:nbme1-26-27
#1808644
  15121974 - 07/09/09 15:45
 
  ans.......c,d  
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* Re:nbme1-26-27
#1808645
  rubina_c - 07/09/09 15:45
 
  c and d  
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* Re:nbme1-26-27
#1808655
  alendronate - 07/09/09 15:51
 
  cd  
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* Re:nbme1-26-27
#1809155
  bobanpjoseph - 07/10/09 06:04
 
  Secondary amenorrhea
The following are causes of amenorrhea after normal periods have been present at an earlier time:

Hypothalamic causes
Weight loss, which could be due to disease, simple dieting, excessive exercise, or anorexia nervosa.
Excessive weight gain (obesity). Obesity itself can disrupt the control of sex hormones. Fat cells can change the female hormone estrogen to the male hormone androgen, and a large enough number of fat cells can cause acne, facial hair, and loss of periods. The condition polycystic ovarian syndrome can come about from obesity (although sometimes obesity is not present). Also, obesity can give rise to type 2 diabetes mellitus, which can disrupt menstruation if it is severe and poorly controlled.
Excessive exercise. Although exercise is generally healthy, excessive exercise can be associated with amenorrhea. [9] This generally happens if the girl or woman exercises the equivalent of running over 25 miles per week. Participation in other competitive sports, such as basketball, soccer, volleyball, and tennis, can also frequently entail daily, vigorous exercise and running. Furthermore, certain sports and activities, such as cheerleading, gymnastics, and modeling, are associated with high rates of anorexia, as there may be strong social pressure to keep a low body weight.
Stress. It is not uncommon for a high stress level to delay menstrual periods or cause a missed period altogether. This was known in one college as "finals-week amenorrhea." Although stress-induced amenorrhea may be short-lived, it may be particularly anxiety-producing, especially in young girls who are otherwise prone to stress and are already in a stressful environment. The possibility of pregnancy may add to the anxiety. In some cases, the stress may continue for a prolonged period and may fit the definition of secondary amenorrhea, lasting 3 months or more. If there is a death of a close friend or relative, bereavement may also delay menstrual periods, as a subtype of stress-induced amenorrhea. Physical stress can result in amenorrhea. Some female soldiers deployed in Iraq have amenorrhea due to a combination of extreme heat and extreme stress.
Chronic illness. Any systemic illness may apply stress on the body, resulting in the body's need to conserve strength and resources; this may lead to amenorrhea.
Medications (drug-induced amenorrhea). Medications that can cause amenorrhea include oral contraceptives, other medications containing estrogen or progesterone, phenothiazine, or some illicit drugs of abuse.
Pituitary causes
Craniopharyngioma, a tumor in the stalk of the pituitary gland. Due to direct damage to the pituitary gland, this tumor results in a lack of production of the hormones LH, FSH, and GnRH, as well as TSH and prolactin. This tumor generally occurs in children between 5 and 10 years of age, and accounts for 9% of all brain tumors in children.
Prolactinoma, a prolactin-producing tumor in the pituitary gland. Small prolactinomas have been found in about 10% of normal people, based on autopsy results, but significant prolactinomas are rare, found in only 14 out of 100,000 people. The high levels of the prolactin hormone inhibit the other hormones and the large mass in the pituitary gland also prevents the other hormones from regulating the menstrual cycle.
Sheehan syndrome, which is hemorrhage (bleeding) and necrosis (cell death) of the pituitary gland due to the sudden loss of blood and loss of blood pressure during childbirth. This condition occurs only with extreme losses of blood, although milder variants of this condition may be more common than expected. The condition may be mild or severe, temporary or permanent. It can result in difficulty breastfeeding, hypothyroidism, and amenorrhea.
Hypothalamic hamartoma, a blood deposit or mass in the hypothalamus, causing an inability to regulate the pituitary gland. This can result in delayed puberty and amenorrhea, although it can also result in precocious puberty.
Ovarian causes
Ovarian failure, or ovaries that once were normal now failing to produce enough estrogen and progesterone to cause menstrual cycles or fertility
Radiation to the ovaries can occur in the treatment of some cancers, or may be due to radiation exposure in the environment
Surgery: Surgical removal of the ovaries, called oophorectomy, is an obvious cause of the ovaries not functioning. Other surgeries in the general abdominal region may cause adhesions to form and may then cause damage to the ovaries. This would be rare, as both ovaries need to stop functioning in order to produce ovarian failure.
Chemotherapy slows or kills the fastest-growing cells in the body, and in young women of reproductive age, this includes the cells of the ovaries. Also, certain chemotherapy agents are known to cause specific damage to the ovaries. The ovarian failure may be temporary, while chemotherapy is actively being taken, or may be permanent.
Autoimmune disease: The body may make antibodies that attack the cells of the ovaries, resulting in autoimmune ovarian failure. This is very rare, but may occur in women who already have other autoimmune diseases, such as lupus or Addison's disease.
Endometriosis occurs in 5% to 10% of women. Ovarian failure may be due to the complications of endometriosis and the destruction of the ovaries, or it may be due to the surgical removal of the ovaries as a treatment for endometriosis.
Polycytic ovarian disease, which is associated with obesity, insulin resistance, glucose intolerance, high levels of LH in relation to FSH, amenorrhea, acne, and hirsutism (excessive body hair growth).
Uterine causes
Asherman syndrome, which describes a uterus crisscrossed by scar tissue or adhesions. The syndrome is usually caused by dilation and curettage (D&C), a procedure in which the uterus is cleaned out after complicated miscarriages or elective abortions, in order to remove any remaining portions of placenta, tissue, or fetal matter. The adhesions that sometimes form after this procedure then lead to amenorrhea and infertility.
Hormonal causes
Pregnancy: This is the most common cause of secondary amenorrhea, even out of cases where the cause is initially not known. Even if several months have elapsed since the last period, the woman with secondary amenorrhea may have a pregnancy she doesn't know about, as some women may have little weight gain or symptoms of pregnancy in the first few months other than a loss of periods.
Lactation amenorrhea occurs normally after childbirth if a woman continues breastfeeding. If a woman breastfeeds regularly and exclusively, she may have her periods delayed for even a year, and on average, about 7 months. This time period also is a natural form of delaying childbirth, as the woman is infertile during this time period.[10] However, the absence of periods can not be wholly relied upon as contraception: the first ovulation occurs 2 weeks before the first menstrual period after childbirth, and a woman could conceive a child even before having her first period after childbirth.
Cushing syndrome: High levels of cortisol, as happens in Cushing syndrome, can inhibit menstruation
Hyperthyroidism: Hyperthyroidism can decrease, disrupt, or stop menstrual cycles
Hypothyroidism: Hypothyroidism can interfere with menstrual cycles, making menstual cycles irregular, and in some cases, can cause amenorrhea. Even if hypothyroidism is found in a particular woman with amenorrhea, care should be taken to ensure that the woman does not have a general lack of pituitary hormone production, as can be seen in a prolactinoma or craniopharyngioma.
Androgen excess: Signs of virilization (becoming more male-like) may be seen in androgen excess. This could be due to a tumor that is secreting male sex hormones. This tumor may be in the adrenal glands or in the ovaries. Also to be considered is the actual ingestion of male sex hormones, such as testosterone or androstenedione.
 
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