What is PCOS in Lean women

PCOS or Polycystic Ovarian Syndrome is a clinical condition which affects about 3.7% to 22.5% women in India. It is primarily an Endocrine disorder which was described for the first time in 1935 by Stein and Leventhal. In 2003, the European Society of Human Reproduction & endocrinology ( ESHRE) & American society of Reproductive Medicine ( ASRM ) revised the criteria for PCOS to include the following :

• Oligo/Anovulation ( ie delayed or absence of release of egg from the ovary ) leading to menstrual irregularities.
• Polycystic ovarian morphology on Ultrasound ( ie 10-12 follicles in either ovary and/or increased ovarian volume >10cm3 ).
• Clinical or Biochemical evidence of Hyperandrogenism ( ie manifestations of increased male hormones-androgens in the body ) provided, the other causes leading to excess androgens in the body have been excluded.

So for most of us, the mention of PCOS creates a mental image of an overweight / obese girl with menstrual irregularities, facial hair , acne and fertility problems. But hey ! are you aware that there is also a subset of women who have a normal weight or might even be underweight and still suffer from PCOS ? Studies claim that upto 24.39% of women with PCOS may be non-obese with a BMI <23 Kg/m². These women constitute what we call as ‘Lean PCOS’.

What is BMI?

BMI ( Body Mass Index ) is a measure of body fat based on height and weight that applies to adult men & women. It is calculated as a ratio of weight of a person in Kilograms divided by her height in metres squared and is written as Kg/m² based on the calculation, a person is categorized as normal weight/ overweight or obese as follows
Underweight - < 18.5
Normal- 18.5 – 24.9
Overweight- 25 – 29.9
Obesity- ≥30

In children & teenagers, the interpretation differs slightly and a BMI of 95th percentile or above for a child of a given age & gender is considered obese.

What is lean PCOS?

So every woman with PCOS may be having a different BMI from other women & belong to a different category based on her BMI. The women who have a BMI less than 24.9 Kg/m² constitute the non-obese group and these non-obese women with PCOS are called Lean PCOS women. In Asian countries, this cutoff for BMI is 23Kg/m². It is important to identify these women as the manifestations & treatment of the disease differ for them as compared to those who are obese. But women, especially young girls, with lean PCOS may not always have gross manifestations of PCOS ie menstrual irregularities or facial/body hair, etc, and may remain undiagnosed for a long time until they face problems in conceiving or developing features of the metabolic syndrome. Acne & facial hair might get overlooked in a young adolescent girl attributing these to normal pubertal changes. The diagnostic criteria for PCOS remain the same in lean women as in obese women and it is important to consult a doctor if you have any of the features even though you might be a normal weight or an underweight girl.

How does lean PCOS differ from PCOS in obese women?

PCOS is a complex disorder with two phenotypes- Obese and Lean PCOS. Both these phenotypes have few similarities but differ in their clinical, biochemical, hormonal & metabolic presentations. Increased fat deposition in the upper part of the body, calculated by measuring the waist to hip ratio, is raised to >0.85 in both categories of PCOS. This truncal obesity of the upper body is said to be a male ( android ) pattern of fat deposition as opposed to the female ( Gynaecoid) pattern in which the fat is deposited more around the hips & thighs. An android pattern of fat distribution is associated with an increased risk of cardiovascular diseases, hypertension, Diabetes & atherosclerosis. Thus even though the lean PCOS women have a normal body weight & height ratio, the android fat distribution predisposes them to similar health risks of hypertension, cardiac disease, atherosclerosis, etc like their obese counterparts with PCOS.

The risk of Hypertension & Metabolic Syndrome is increased in both Obese as well as lean PCOS women. However, the risk is slightly higher in Obese women.

Menstrual irregularities and clinical features of hyperandrogenism ( ie acne, hair loss, abnormal facial & body hair, etc ) are more common in obese women with PCOS compared to those who are lean & have PCOS. Even though lean women may also be affected by them, Insulin Resistance & Diabetes Mellitus are significantly more common in Obese PCOS women. However, it has been seen that some amount of Insulin resistance is present in the majority of PCOS women irrespective of whether they are lean or obese. Similarly, the incidence of Endometrial Hyperplasia is significantly more in obese PCOS although some women with lean PCOS may also report these findings.

Dyslipidemia ie deranged lipid profile is more common in Obese PCOS than lean PCOS. Lean PCOS women demonstrate a lower resistance to stress & anxiety as compared to obese PCOS women.

Pregnancy complications are expected in lean as well as obese PCOS women but in obese women, the manifestations may be exacerbated by the obesity while lean women may suffer milder problems.

What are the goals of treatment in lean PCOS women?

The goals of treatment in lean women with PCOS differ slightly from those in obese women with PCOS. As opposed to obese PCOS, women with lean PCOS are unlikely to benefit from weight loss and the main aim of treatment is to

• Improve Insulin sensitivity.
• Prevent weight gain.
• Restore ovulation.
• Decrease stress.
• Decrease the circulating levels of free androgens ( male hormones).
• Maintain adequate nutritional status & dietary intake.

What are the treatment options for women with lean PCOS?

For lean PCOS, the treatment revolves around lifestyle changes, dietary modifications & physical exercise apart from medications which may be needed in a few cases for assisting in attaining pregnancy or improving the metabolic syndrome. Remember that caloric restrictions do not have much role here as lean women do not necessarily need to lose weight. Instead, they need to focus on preventing weight gain & maintain an active lifestyle. This not only improves insulin sensitivity and reduces androgen levels, but also regularizes ovarian function and reduces stress. So the treatment options include:

• Exercise – Regular exercise at least 45 minutes per day helps in managing PCOS in a number of ways: Different types of exercises like strength training, resistance exercises, yoga, cardio, aerobics, etc can help in improving your overall body composition by burning the extra calories & building more of muscle mass. Active muscle also helps to keep burning calories throughout the day which helps in preventing weight gain & maintaining a healthy BMI. Regular exercise decreases the truncal/ visceral body fat and builds muscle, thus improving the fat: muscle ratio in a favorable manner. Exercise releases ‘ endorphins’ which are mood elevators & considered as ‘happy hormones’ which help fight against anxiety & stress.
• Nutrition- Lean PCOS women do not need to decrease their food intake but they do need to focus on ‘Eating right’ in order to maintain their nutritional status and a healthy body. So you need to focus on consuming fresh fruits, vegetables, lean proteins, and foodstuffs rich in both Micro & macronutrients. For more on diet in PCOS refer to the Maitri tutorial on diet in PCOS.
• Supplements- Certain supplements containing calcium, Vitamin-D, Myo-inositol & Zinc have been shown to have a beneficial effect in PCOS but should be taken only after your doctor’s advice.
• Stress management- Yoga, meditation, spending time in nature, regular exercise, indulging yourself in some activity that you enjoy have all been shown to have a beneficial effect on the management of stress & anxiety.
• Ovulation induction- In women who desire to conceive, regular ovulation can be achieved with medications prescribed by your doctor. These may include preparations containing Clomiphene or Letrozole or sometimes injectable hormonal preparations, and they need to be consumed strictly according to medical advice.
• Oral contraceptive pills- These may be needed in a few women with menstrual irregularities that fail to respond to other measures. Assisted Reproductive Techniques – These include IUI or IVF and women with lean PCOS have shown better response to ART as compared to their obese counterparts.
• Treatment of Acne- Basic measures like correct dietary intake, plenty of oral fluids, consuming fruits & vegetables along with good hygiene, facewash & skincare are usually sufficient to reduce acne. However, in some girls, the acne might be resistant & pharmacological medications including antibiotics & retinoid preparations may be needed as prescribed by your doctor.
• Excess facial & body hair – These may be managed by cosmetic measures such as threading, waxing, or laser therapy. Sometimes, your doctor may prescribe certain medications to decrease androgen levels & reduce hair growth.

The Takeaway message

Even though you are lean & normal weight, menstrual irregularity, excess facial/ body hair, acne, difficulty in conceiving, may be a manifestation of underlying PCOS pathology. It is important to recognize & treat this condition not just to alleviate the existing symptoms, but also to prevent the long-term complications of Diabetes, Cardiovascular disease, hypertension & Endometrial cancer. Do not hesitate to meet your gynecologist & get yourself evaluated to ensure whether or not you have PCOS.