PCSK9, LDL-cholesterol levels drop after bariatric surgery

Last Updated: 2017-09-04

By Megan Brooks

NEW YORK (Reuters Health) - Plasma levels of PCSK9 and LDL cholesterol drop after bariatric surgery in severely obese patients, according to what is believed to be the first study to document the impact of bariatric surgery on plasma PCSK9 levels.

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a key regulator of LDL-cholesterol levels. In patients with severe obesity, biliopancreatic diversion with duodenal switch (BPD-DS) surgery leads to substantial weight loss and favorable effects on lipoprotein metabolism.

However, the impact of BPD-DS surgery on PCSK9 levels has been unknown, Dr. Benoit Arsenault and colleagues from Laval University in Quebec, Canada, note in a report online August 24 in the Journal of Clinical Endocrinology and Metabolism.

To investigate, they measured PCSK9 levels in 69 severely obese patients (20 men) before BPD-DS surgery and again 24 hours, five days, and six and 12 months after surgery - and in a comparable control group of 31 individuals at baseline and at six and 12 months. They also measured PCSK9 levels during a three-day period of calorie restriction in seven severely obese patients with type 2 diabetes.

PCSK9 levels increased 13.4% after 24 hours (P=0.02) and decreased 9.5% at 12 months compared to baseline (P<0.0001). LDL-cholesterol levels decreased 36.2% at 24 hours after surgery (P<0.0001) and 30% at 12 months compared to baseline (P<0.0001).

In an email to Reuters Health, Dr. Arsenault said, "We were actually surprised to see a sharp increase in PCSK9 levels 24 hours after bariatric surgery. We conducted another set of experiments and concluded that this increase in PCSK9 levels was not due to the caloric restriction that follows bariatric surgery but could be due to the surgery itself."

The finding that bariatric surgery decreases PCSK9 levels over longer time "could explain to a certain extent why LDL cholesterol decreases after bariatric surgery," Dr. Arsenault added.

"By exploring the acute and chronic effect of BPD-DS surgery on plasma PCSK9 levels, our study provides additional information on the modulation of PCSK9 levels and underscores that long-term weight loss induced by malabsorptive surgery could reduce both PCSK9 and LDL cholesterol levels in patients with severe obesity," the researchers conclude in their paper.

They say additional studies are needed to learn more about the mechanisms underlying the effect of BPD-DS on PCSK9 levels and to identify the clinical impact of BPD-DS on PCSK9 in terms of cardiovascular disease risk.

The study had no commercial funding. Dr. Arsenault has received research funding from Pfizer for scientific work on PCSK9, and two co-authors have received research funding from Johnson & Johnson for scientific work on bariatric surgery.

SOURCE: http://bit.ly/2wymU9U

J Clin Endocrinol Metab 2017.