The case of a 62-year-old American man is a classic example of why it’s important to keep a close eye on rapid weight loss while juggling medications.
At 132kg, the man qualified as obese, which may have contributed to his development of type 2 diabetes and been linked closely with another of his conditions, an under-active thyroid gland, reports ScienceAlert.
Consequently, his family doctor prescribed him with daily insulin injections, as well as a daily dose of a thyroid hormone replacement drug called levothyroxine. He was also told to take a weekly dose of the diabetes and weight loss drug tirzepatide (Zepbound).
The treatment was so effective his weight dropped by 39kg, or almost 30% of his body weight, in just six months. Unfortunately, this came at a price.
Shortly afterwards, he arrived at an emergency department suffering from “palpitations, excessive sweating, confusion, fever and hand tremors”, according to the case study by a team from the University of Colorado.
An examination revealed that the palpitations were a sign of atrial fibrillation, the irregular heartbeat condition that can trigger strokes and heart attacks. Further tests showed this had been brought on by thyrotoxicosis, an over-abundance of a hormone produced by the thyroid.
Or, in this case, a medication designed to look just like it.
Dosages for many medications are weight-based. So as the man lost weight, the relative dosage of levothyroxine crept higher. At his initial weight he was taking 1.5 μg per kilogram of his weight. By the end, that had inadvertently jumped to 2.15 μg per kilogram.
All of this could have been prevented if the man had adjusted his other medications in relation to his changing weight. The levothyroxine should have been adjusted as his weight changed to avoid the thyrotoxicosis and atrial fibrillation, according to the case study authors.
The man also missed a scheduled follow-up appointment with his doctor due to travelling, which may have played a part in this lapse in monitoring.
Losing a lot of weight quickly does come with potential risks, as well as all the health benefits, and previous studies have shown it’s important to maintain good health in other areas while trying to shed kilos.
Tirzepatide has proved very effective in tackling obesity – but when it comes to any extreme weight loss strategy, patients (and their existing medications) need to be closely monitored to prevent other health problems from arising.
“With the increasing use of tirzepatide and other GLP-1 analogues for the treatment of patients with obesity, we recommend closely evaluating those using tirzepatide (every four to six weeks initially) for assessment of therapy response, adverse events, and possible dose adjustment of other concomitant medications,” recommended the authors.
The research was published in JAMA Internal Medicine.
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