A diagnostic work-up should be initiated if there are symptoms of pathology, i.e., if the menstrual disturbance is beyond the normal spectrum of physiological variability. Most mild and moderate disturbances during adolescence are transient and self-limited. Diagnostic steps should be taken if the problems are severe or persisting. The patient’s history is informative concerning her personal situation. Physical and gynecologic examination is performed to evaluate the somatic status. Sexual development and the age of menarche are salient points. If menstrual bleeding has begun, the type and rhythm should be recorded and documented in a menstrual calendar. The normal menstrual cycle has a mean interval of 28 days (±7 days) with a duration of 4 days (±2 - 3 days). There is a physiological range of menstrual flow up to 80 ml.

Abnormalities of the type of bleeding (menorrhagia, hypermenorrhea, metrorrhagia) can be caused by anovulation, imbalance of hormonal factors, and occasionally coagulation disorders. Endocrine exploration is usually not necessary because the results in these patients are usually quite normal. Assessment of the hematological status and a complete blood count may detect a coagulation disorder. A pregnancy test may be indicated.

Abnormalities of rhythm, particularly oligomenorrhea, can be a sign of a real endocrine disturbance. Endocrine exploration is indicated if a prolonged interval persists for longer than 2 years, and earlier if there are symptoms of endocrine disease. Basic hormone radioimmunoassays suffice. This means measuring follicle-stimulating hormone (FSH), luteinizing hormone (LH), prolactin (Prl), estradiol (E2), testosterone (T) and dehydroepiandrosterone-sulfate (DHEA-S). The blood sample should be obtained in the early follicular phase.

Measuring progesterone (P) in the second phase of the cycle can provide information on luteal function. The measurement of basal body temperature will not be performed by teenage girls. Thyroid function should assessed by measuring TSH and, possibly, fT4.

Further steps depend on the results of these initial tests. A single abnormal hormone level should be confirmed by a repeat test because intra-individual variation is considerable. If the levels are normal or within an individual physiological range, expectant management and reassurance are all that is needed.

If testing yields significant abnormalities, further exploration, prophylaxis or treatment may be necessary.

Organic lesions are rare in this age group but have to be ruled out. Signs or symptoms of a tumor, particularly a cerebral lesion, should be investigated with pelvic ultrasound, computed tomography (CT) or magnetic resonance imaging (MRI).