From the Guidelines
Norethisterone can be used by individuals with a high BMI, but its safety profile is a concern, particularly in terms of blood pressure, renal function, and activation of the renin-angiotensin system, as reported by Langrish and colleagues 1. When considering norethisterone for individuals with high BMI, it is essential to weigh the potential benefits against the risks.
- The typical dose for menstrual cycle regulation or postponement is 5mg three times daily, starting 3-4 days before expected menstruation and continuing until bleeding is desired to begin.
- For contraception, norethisterone is usually combined with estrogen in combined hormonal contraceptives, with dosages varying by specific formulation.
- Women with a BMI over 30 should be aware that hormonal contraceptives may be slightly less effective and carry a somewhat higher risk of venous thromboembolism compared to women with lower BMIs, as highlighted in a recent review on obesity management in adults 1. However, these risks are still generally lower than the risks associated with pregnancy.
- Alternative contraceptive options like intrauterine devices or progestin-only methods might be preferable for women with very high BMIs or additional risk factors. The reduced effectiveness of norethisterone in individuals with high BMI occurs because higher body weight can increase drug metabolism and distribution volume, potentially lowering blood concentrations of the hormone. Despite these considerations, norethisterone remains a viable option for many women with high BMI when benefits outweigh potential risks, but natural micronized progesterone may be a safer alternative, given its favorable profile in minimizing hormonal-related cardiovascular risks 1.
From the Research
Norethisterone and High BMI
- The relationship between norethisterone and high BMI is not directly addressed in the provided studies, but some studies touch on the effects of norethisterone on body weight and metabolic parameters 2, 3, 4.
- A study from 1992 found that the use of norethisterone in combination with ethinyl estradiol resulted in increased triglyceride levels and 2-hour glucose levels, but the changes in metabolic parameters may not have clinical significance 2.
- A study from 2007 compared the effects of two oral contraceptives, one containing norethindrone acetate and the other containing norgestimate, on body weight, and found that the mean weight change after 6 months was +0.57 kg and +0.71 kg, respectively, and only 0.3% of subjects in both groups experienced a 10% change in weight 3.
- Another study from 2009 found that the use of norethisterone acetate in combination with estradiol resulted in a slight increase in body weight (+1.00 kg) compared to the use of drospirenone with estradiol (+0.18 kg) 4.
- There is no direct evidence to suggest that norethisterone has a significant impact on high BMI, but it may have effects on body weight and metabolic parameters that could be relevant to individuals with high BMI 2, 3, 4.
- The effects of norethisterone on body weight and metabolic parameters may be influenced by the dose and duration of use, as well as individual factors such as age, weight, and health status 5.