Management of Amenorrhea and Inconsistent Cycles

Initial Diagnostic Workup

The American College of Obstetricians and Gynecologists recommends measuring serum prolactin levels to evaluate for hyperprolactinemia, which commonly causes amenorrhea and may indicate a pituitary adenoma 2, 1
Measuring TSH is essential to exclude thyroid dysfunction as a reversible cause of amenorrhea 2
Measuring FSH and LH levels, ideally between cycle days 3-6 if any bleeding occurs, helps differentiate between ovarian failure and hypothalamic-pituitary dysfunction 2, 1
Measuring testosterone and androstenedione is necessary if signs of hyperandrogenism are present to evaluate for polycystic ovary syndrome (PCOS) 2, 1

If prolactin is elevated, ordering a pituitary MRI is crucial to rule out prolactinoma, as this is the most common pathologic cause of hyperprolactinemia 2, 1
If FSH is elevated with low/normal LH, diagnosing primary ovarian insufficiency is necessary, and counseling about unpredictable ovarian function and fertility options should be provided 2, 1
If LH/FSH ratio is >2 with normal/elevated LH, suspecting PCOS and ordering a pelvic ultrasound to identify ovarian cysts and thickened ovarian stroma is recommended 2, 1

Never assuming amenorrhea is benign without evaluation is a common error, as prolonged hypoestrogenism increases risks of osteoporosis and cardiovascular disease 2, 1
Delaying pituitary imaging if prolactin is elevated can lead to visual field defects and require urgent intervention 2, 1
If pelvic ultrasound shows structural abnormalities, referring to gynecology for further evaluation is necessary 2, 3