Case 10: Absent periods

 

Case 10: Absent periods

CASE 10: ABSENT PERIODS

History

A 24-year-old woman presents with the absence of periods for 9 months. She started her

periods at the age of 13 years and had a regular 28-day cycle until 18 months ago. The periods

then became irregular, occurring every 2–3 months until they stopped completely. She has

also had headaches for the last few months and is not sure if this is related. She has a regular

sexual partner and uses condoms for contraception. She has never been pregnant. There is no

previous medical history of note.

She works as a primary school teacher and drinks approximately 4 units of alcohol per week.

She does not smoke or use recreational drugs. She jogs and swims in her spare time.

Examination

The woman is of average build. The blood pressure and general observations are normal. The

abdomen is soft and non-tender and speculum and bimanual examination are unremarkable.

INVESTIGATIONS

Normal

Follicle-stimulating hormone 7 IU/L Day 2–5

1–11 IU/L

Luteinizing hormone 4 IU/L Day 2–5

0.5–14.5 IU/L

Prolactin 1800 mu/L 90–520 mu/L

Testosterone 1.8 nmol/L 0.8–3.1 nmol/L

Magnetic resonance imaging (MRI) scan of the head is shown in Fig. 10.1.

Questions

• What is the diagnosis?

• Are any further

investigations indicated?

• How would you manage

this patient?

Figure 10.1 MRI scan of the head.100 Cases in Obstetrics and Gynaecology

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ANSWER 10

The investigations show a high-prolactin and a space-occupying lesion in the pituitary fossa

in the region of the anterior pituitary as detailed in Fig. 10.2. This is consistent with a pituitary adenoma (prolactinoma).

Prolactin should always be measured in a woman with amenorrhoea. Care should be taken in

interpreting the results, as levels up to 1000 mu/L can be found as a result of stress (even due

to venepuncture), breast examination or in association with polycystic ovarian syndrome.

Above 1000 mu/L the usual cause is a pituitary adenoma (micro- or macroscopic).

! Differential diagnosis of secondary amenorrhoea

• Hypothalamic:

• chronic illness

• anorexia

• excessive exercise

• stress

• Pituitary:

• hyperprolactinaemia (e.g. drugs, tumour)

• hypothyroidism

• breast-feeding

• Ovarian:

• polycystic ovarian syndrome

• premature ovarian failure

• iatrogenic (chemotherapy, radiotherapy, oophorectomy)

• long-acting progesterone contraception

• Uterine:

• pregnancy

• Asherman’s syndrome

• cervical stenosis

Figure 10.2 Arrow shows a small

asymmetrical enlargement of pituitary

gland, representative of a small

pituitary adenoma (prolactinoma).Case 10: Absent periods

25

Further investigation

Visual fields should be checked, as visual field defects may be present with a large

tumour. Thyroid function should be tested as hypothyroidism is also a cause of amenorrhoea. The other important investigation in any woman with amenorrhoea is a pregnancy test, although with this history this would be very unlikely. (Prolactin is also

raised in pregnancy.)

Management

Most prolactinomas respond to medical treatment with bromocriptine or cabergoline. These

are both dopamine agonists, which inhibit prolactin secretion from the anterior pituitary.

Cabergoline is generally the first-line agent in the management of prolactinomas and idiopathic hyperprolactinaemia due to higher affinity for D2 receptor sites, more rapid resolution

of prolactin levels, menstruation and return of ovulatory cycles and a better side effect profile.

Maintaining the prolactin level below 1000 mu/L causes menstruation (and ovulation) to

return in most women. This can be continued indefinitely or until pregnancy is achieved if

the presenting complaint is of infertility.

KEY POINTS

• Hyperprolactinaemia is a common cause of secondary amenorrhoea.

• Prolactin levels up to 1000 u/L may be due to non-pathological causes such as

stress.

• Prolactinomas can usually be treated effectively with medical suppression, and

surgery is only indicated rarely.