Parathyroid disease and hyperparathyroidism are associated with weight gain. Patients with hyperparathyroidism weigh more than their peers. The worries about gaining weight after parathyroid surgery are understandable but unfounded. It is a myth that parathyroid surgery and removing a parathyroid tumor causes you to gain weight.

Weight gain is a common concern for patients with many hormone problems, including hyperparathyroidism. This blog was prompted by a recent rash of patients asking us if the parathyroid operation was going to make them gain weight. It absolutely does not happen because of the parathyroid surgery. Let’s look at weight gain in patients with hyperparathyroidism scientifically before and after parathyroid surgery.

Weight gain associated with the disease hyperparathyroidism has been known for decades. Parathyroid tumors make people gain weight. Essentially all publications on this topic that include the weight of the patients has shown than patients with parathyroid disease weigh more than their peers. The best scientific study of weight gain in hyperparathyroidism was published in one of the best medical journals a few years ago and included several thousand patients. Here is a short version of their report, most of it exactly as written but some has been changed slightly to make it more readable for the non-doctors in the audience (footnote and link to the actual paper is at the bottom).

Hyperparathyroidism and Weight Gain

Association between Primary Hyperparathyroidism and Increased Body Weight: A Meta-Analysis:  Primary hyperparathyroidism is associated with an increased prevalence of hypertension, insulin resistance, lipid/fat/cholesterol issues, cardiovascular mortality, and cancer.  We previously reported that patients with primary hyperparathyroidism are heavier than age-matched controls. To see if this was true for all patients or just ours, we searched MEDLINE for English language studies that reported body weight or body mass index in subjects with primary hyperparathyroidism and a healthy age-and sex-comparable control patients with normal calcium levels. Seventeen eligible studies/publications on weight and parathyroid were identified. Subjects with primary hyperparathyroidism were 8.5 pounds (3.34 kg)  heavier than controls in 13 studies reporting body weight (p < 0.00001).  In four studies reporting body mass index, subjects with primary hyperparathyroidism had an increased body mass index of 1.13 kg/m2 compared with controls. Statistical analysis showed that subjects with primary hyperparathyroidism had an increased weight or body mass index  (p < 0.00001) compared with people who have normal calcium levels. We conclude that patients with primary hyperparathyroidism are heavier than their peers with normal calcium levels, and that increased body weight may contribute to the reported associations between primary hyperparathyroidism and some complications. Footnote and link to entire article is at the bottom of this page:  J Clin Endocrinol Metab (2005) 90 (3): 1525-1530.

What do Our Parathyroid Patients Say About Weight Gain After Parathyroid Surgery?

We have performed well over 30,000 parathyroid operations and we rarely get patients complaining of weight gain after their parathyroid surgery. And our patients have access to us for years via email and such. We don’t have lots of patients calling to say they got fat after their parathyroid operation. Yes, a lot of them complain about gaining weight or the inability to lose weight when they have high calcium and hyperparathyroidism, but we simply do not have lots of patients calling or emailing us after surgery to say they gained weight. Of course some people gain weight after surgery, as this is common as we get older, and common in our society. Yes, some of our patients gain weight. But the parathyroid operation did not cause the problem. Removing a tumor didn’t cause weight gain. Note: We’re looking into weight gain/loss in our patients at this time with a survey–so check back here in a few months.  But let’s keep discussing what we already know.

Weight loss is actually more common after parathyroid surgery than weight gain. Remember that the number one symptom of hyperparathyroidism is fatigue. People with a high calcium and/or PTH often complain that they are tired all the time. Or that after about noon every day they just want to take a nap, but the nap doesn’t help them feel better. Our patients say they are “tired of being tired”. This chronic fatigue means that people are less active. They aren’t outside working in the yard. They tend to spend more time on the couch than they used to. And most gain some weight, as noted in the scientific literature discussed above.

Weight Gain with Hyperparathyroidism: Is it Just Because I’m Tired all the Time?

There may actually be a scientific / biochemical reason for gaining weight when you have a parathyroid problem that is more complex than just being tired and less active because you feel like crap. Another group of doctors published some research on this topic a few years ago. They found that fat cells don’t break down their fat (called lipolysis) very well when exposed to high PTH levels. Thus, their research suggests the excess PTH has some role in preventing weight loss in patients with hyperparathyroidism. Dr McCarty’s research is important in that it suggests the association between weight gain and hyperparathyroidism may be reversed if the parathyroid tumor is removed.  The footnote to this research and the article is at the bottom of this page.

Weight Gain Caused by Parathyroid Surgery: A Facebook Myth

Weight gain caused by removing parathyroid tumors is a myth. Weight loss is actually more common.

We have been performing parathyroid surgery exclusively for decades, on tens of thousands of patients. In 25 years, nobody has asked us if the parathyroid operation was going to cause them to gain weight–until about 3 months ago. Now somebody asks a couple of times per week if the operation is going to make them fat. When we look puzzled and ask why this question is being asked, our patient will say that they read about it on a Facebook post or some online question/answer board. At first we were surprised because there absolutely is no cause-and effect relationship. But after hearing this question twice in one week, we couldn’t sit back and let this go. We have to put an end to this Facebook Myth that the act of having parathyroid surgery can cause weight gain. In fact the opposite is true–there is overwhelming evidence that having hyperparathyroidism is associated with weight gain and difficulty losing weight.  After the operation most people feel better and are more active and many will lose weight. But the vast majority just keep the same weight–nothing happens to their weight.  Of course some may gain weight, but the concept that weight gain is caused by parathyroid surgery is unfounded and there is no scientific basis for this. It has never been reported in the medical literature and there is no physiologic mechanism for this to happen. There is no reason that removing a parathyroid tumor and re-establishing normal body hormone and calcium levels would cause weight gain. Moreover, we just don’t see weight gain in large numbers of our patients and have very few patients who complain about this in general… and we see more of this (by far) than anybody else in the world. Another important point is that we don’t see patients who have a normal body weight gaining weight after the operation. When we do see weight gain, it is almost always in folks who are a bit (or a lot) over weight to begin with–as outlined and discussed at the beginning of this page. This is a very complex issue–why they gained weight with the parathyroid tumor in the first place.

Then Why do Some Patients Gain Weight After Parathyroid Surgery?

But if there is no cause-effect relationship between parathyroid surgery and weight gain, why are people chatting about this on Facebook? Clearly some people gain weight after a parathyroid operation. We don’t doubt that!  But the operation didn’t cause the weight gain… So what did? Well, we’ve talked to some of them and asked some questions. Some people never felt better after their parathyroid operation making us think that some may not be cured of their parathyroid problem. Some were told they had 4-gland hyperplasia which is quite uncommon, and this leads us to think that something else is going on–they may not have had hyperparathyroidism in the first place (almost everybody has a tumor, so when they don’t find a tumor during surgery most surgeons remove 3 glands and call it hyperplasia instead of actually telling the patient that they didn’t have hyperparathyroidism in the first place). Some of these folks have the same labs after the operation as they had before the operation. On the flip side, some feel so much better that they are doing things that they love to do, like cooking and going out to eat–so they are taking in more calories enjoying life more. Some people that we’ve talked to who gained weight after their parathyroid operation were obese and had type II diabetes during the time they had hyperparathyroidism. Of course, fixing the hyperparathyroidism isn’t going to change the diabetes in most patients (it can make it much easier to control in some). It is quite hard for diabetics to lose weight, and many slowly gain weight with time (even though they know they should not).

Another fairly common reason for weight gain after parathyroid surgery is that fixing the parathyroid problem unmasks a thyroid problem. About 20% of patients undergoing parathyroid surgery are on thyroid hormone supplementation already and many will need to have some adjustments after the parathyroid operation. Some patients have some thyroid tissue removed during the parathyroid operation, or have some of the blood supply to the thyroid cut. This can lead to decreases in thyroid hormone production that are subtle and not noticed is not looked for. Some of these patients need to be on thyroid hormone and they are not. Some of these minor changes in thyroid hormone from removing thyroid tissue or cutting the blood supply may not be recognized, and this can be contributing to slow weight gain. The bottom line is that weight gain is complex. It isn’t simple.

Of course it is possible that people gain weight after parathyroid surgery. We do not doubt that this happens! People also gain weight after hip surgery, and after knee replacement surgery. But the operation didn’t cause the weight gain. Patients with hyperparathyroidism are more likely to be overweight and obese than their peers. And thus, they may be more subject to weight gain over time for many complex reasons, regardless of what operation they have. So have your parathyroid operation with confidence. Get that tumor out of your neck and get back to enjoying life and all the activities that you are missing out on. And don’t worry about getting fat after parathyroid surgery. But be smart and pay attention to your thyroid hormone levels after your operation. Pay attention to your activity levels and your caloric intake. Make sure your parathyroid problem is really fixed.  But there is no cause-and-effect relationship that parathyroid surgery causes weight gain. This is a Facebook myth.

Important links and articles cited above:

• Read more about the symptoms of hyperparathyroidism.
• Read about the symptoms of thyroid nodules.
• Research article 1 above:  Association between Primary Hyperparathyroidism and Increased Body Weight: A Meta-Analysis. Bolland, Grey, Gamble, Reid.  J Clin Endocrinol Metab (2005) 90 (3): 1525-1530
• Research article 2 above:  PTH excess may promote weight gain by impeding catecholamine-induced lipolysis-implications for the impact of calcium, vitamin D, and alcohol on body weight. McCarty MF, Thomas CA. 2003 Nov-Dec;Med Hypotheses.61(5-6):535-42.

image credits: Eatthis.com, Imperialcollege.