Premenstrual syndrome and its luteal-phase timing
Premenstrual syndrome (PMS) is a pattern of symptoms that recur in the luteal phase (the second half of the menstrual cycle, after ovulation) and resolve with menstruation (the period).
Remember
PMS is recognised by its timing rather than by any single symptom: the symptoms build in the days before a period, usually ease soon after bleeding starts, and leave a relatively symptom-free interval.
Premenstrual syndrome (PMS) is recognised by its timing. The symptoms recur in the luteal phase, the second half of the menstrual cycle, which runs from ovulation until the next period. They resolve with menstruation, and a relatively symptom-free interval follows before they return in the next cycle.
The symptoms are both physical and psychological. Typical psychological symptoms include anxiety, low mood and mood swings, while typical physical ones include breast tenderness and headaches. It is the timing, rather than any single symptom, that makes the diagnosis.
The cause is not thought to be abnormal hormone levels. One proposed explanation is that some women are unusually sensitive to the normal rise and fall of oestrogen and progesterone across the cycle. PMS is recognised from the history, and a symptom diary kept over at least two cycles shows whether the pattern really is cyclical (recurring with the cycle). The symptoms must also be severe enough to affect daily life, and the diagnosis is made only when other conditions that could explain them are absent.
Look-alikes (conditions with similar symptoms) are separated from PMS by timing. Symptoms present all month suggest depression or another condition. Cramping pain that peaks during bleeding is dysmenorrhoea (period pain, where the womb tightens during the period). Low mood that is present all month but worsens before each period is premenstrual worsening of a condition already there, not PMS.
The most severe form is premenstrual dysphoric disorder (PMDD), with much more intense symptoms and very marked mood symptoms.
Key facts
- Timing
- symptoms build in the days before a period, usually ease soon after bleeding starts, and leave a relatively symptom-free interval
- Cause
- not thought to be abnormal hormone levels, but one proposed explanation is increased sensitivity to the normal rise and fall of oestrogen and progesterone
- Diagnosis
- made from the history, with a symptom diary kept over at least two cycles to show the pattern
- Constant symptoms
- symptoms present all month suggest depression or another condition rather than PMS
- Period pain
- cramping pain that peaks during bleeding is dysmenorrhoea rather than PMS
- Severe form
- premenstrual dysphoric disorder (PMDD), with much more intense symptoms and very marked mood symptoms
Exam traps
- Symptoms that persist through the follicular phase (the first half of the cycle, from the start of the period until ovulation) do not fit PMS, because they lack the symptom-free interval after menstruation that defines PMS, and their premenstrual onset is insufficient for the diagnosis.
- Low mood present all month with premenstrual worsening does not show PMS, because PMS has a relatively symptom-free interval after menstruation, and it suggests premenstrual worsening of depression.
- Cramping pain that begins before a period and peaks during the bleeding describes dysmenorrhoea rather than PMS, because PMS symptoms improve as bleeding begins instead of peaking then.
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