Dear Doctor, I think I have the most irregular menstrual cycle ever. Sometimes I go two days, sometimes a week! Sometimes I skip a month and sometimes it comes twice! Even the flow is inconsistent. Some days it is heavy, others very light. What is the reason behind this? How can I get a normal cycle because mine is unpredictable and I just never know when it is going to hit.Pauline Dear Pauline What is your age currently? When did your menses start and how long have you had this problem of irregular menses? Answers to these questions can help find the underlying cause of irregular menses in your case. Menses start around puberty and continue till menopause. Menstrual cycle is governed by the equilibrium of two hormones, estrogen and progesterone, the levels of which are influenced by hormones from the pituitary gland and adrenal glands. Initial few cycles after puberty tend to be irregular, a time period which can be from six months to even up to 12 months in some cases. After that, a set pattern of duration of bleeding and amount of flow is set, which recurs every month. It can be from three to five, even up to seven days. The dates can be consistent or plus, minus one week. Around menopause as well, the cycles can be naturally irregular, both duration and amount of flow of blood during menses being altered. It is disturbed during pregnancy and breastfeeding. One may start a new pattern of menstrual cycles after child birth and stopping breastfeeding. Stress, obesity, excess physical activity, use of alcohol, can also alter the menstrual cycles. Hormonal disorders such as overactive or under active thyroid gland, disorders of the pituitary or adrenal glands, polycystic ovarian syndrome (PCOS), are other disorders which can disrupt the menstrual cycle. Drugs like corticoids, hormonal contraceptive pills, can change the regular menstrual cycles as side effects. Among disease conditions, severe anaemia is known to affect menstrual cycles. Hormone producing cancers or ovarian tumours can also have same effect. The underlying cause of disturbed menstruation can be known from history and clinical examination. Tests of blood hormone levels and pelvic ultrasound examination are also useful in this regard. Treatment depends on treating the underlying cause detected. Dr. Rachna Pande is a specialist in internal medicine. rachna212002@yahoo.