Parathyroid disease and hyperparathyroidism are associated with weight gain. 

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 before and after parathyroid surgery.

One 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. 

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

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 Myth?

There is no physiologic mechanism for parathyroid surgery to cause weight gain. 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.

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? 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. 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. 

Additional Resources:

• Read more about the signs and symptoms of hyperparathyroidism.
• Read about the symptoms of thyroid nodules.
• Read more on the Parathyroid blog.
• Become our patient.
• Check out our sister surgeons at the Clayman Thyroid Center, the Scarless Thyroid Surgery Center and the Carling Adrenal Center. We are now united under one roof, operating at the Hospital for Endocrine Surgery. 

References:

• 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