Too much levothyroxine can lead to hyperthyroidism, which can exacerbate heart issues. Indeed, there is a potential risk of causing more harm than good, especially in people with subclinical hypothyroidism and heart failure.
It is not surprising that some individuals experience cardiovascular complications following LT4 treatment as thyroid hormones regulate cardiac functioning. Indeed, increased thyroid hormone levels are associated with an increased risk of developing heart arrhythmias (10).
This is especially true in patients with heart failure. While levothyroxine replacement may improve heart failure, it is possible that in this group it could have harmful effects, especially if the levothyroxine dose is too high.
Excess thyroid hormone also causes the heart to beat harder and faster and may trigger abnormal heart rhythms. One is atrial fibrillation, a disorganized rhythm in the heart's upper chambers.
Heart problems
If you have an untreated underactive thyroid, your risk of developing cardiovascular disease is increased. This is because having low levels of the hormone thyroxine can lead to increased levels of cholesterol in your blood.
Levothyroxine may cause serious or life-threatening problems when given in large doses, especially when taken with amphetamines such as amphetamine (Adzenys, Dyanavel XR, Evekeo), dextroamphetamine (Dexedrine), and methamphetamine (Desoxyn).
Thyroxine increases resting heart rate and left ventricular contractility. T3 causes decreased systemic vascular resistance (SVR) by a direct effect on the arteriolar smooth muscle cells.
The more commonly reported adverse events have included those of hyperthyroidism due to therapeutic overdose including arrhythmias, myocardial infarction, dyspnea, muscle spasm, headache, nervousness, irritability, insomnia, tremors, muscle weakness, increased appetite, weight loss, diarrhea, heat intolerance, ...
This medicine may cause severe hypothyroidism, called myxedema coma, which may be life-threatening and requires immediate medical attention.
The common clinical signs following thyroxine overdose can either be limited to tachycardia, agitation, nervousness, insomnia, anxiety, tremor [2], or severe features, though less likely, like thyroid storm involving cardiac, neurological, respiratory and thermoregulatory center [3].
Common side effects of levothyroxine include heat intolerance, a fast heart rate, and diarrhea. More serious levothyroxine side effects are also possible. If you experience side effects like tremors or mood changes, talk to your healthcare provider as soon as you can.
Stopping levothyroxine usually leads to the return of hypothyroidism symptoms. In the review mentioned above, only about 12% of people with overt hypothyroidism were able to stop their thyroid medications successfully. If you've had your thyroid completely removed, you'll need thyroid medications for life.
How long will I take levothyroxine for? Treatment with levothyroxine is usually lifelong. If you stop taking levothyroxine your symptoms are likely to come back.
IBSA Pharma Inc. Issues Voluntary Nationwide Recall of Select Lots of TIROSINT®-SOL (levothyroxine sodium) Oral Solution Due to Subpotency | FDA.
As the main treatment for a sluggish thyroid, levothyroxine is meant to be taken for life. Stopping this medication may result in a return of symptoms such as: Fatigue. Weight gain.
Thyroid hormones help cells function and are also involved in their breakdown. They also help regulate our moods, reproductive function, metabolism, and gastrointestinal function. Levothyroxine is generally taken life-long when used to treat hypothyroidism (low thyroid levels) unless the cause is transient.
Armour Thyroid and levothyroxine are made differently
Today, thyroid extracts are made from the dried and ground thyroid glands of pigs. So they're often considered a more “natural” form of thyroid replacement. Along with Armour Thyroid, NP Thyroid is another natural thyroid option available on the market.
If you have an overactive thyroid, it can speed up your heart function, making your heart beat too quickly. Over time, hypothyroidism can “wear out” your heart, leading to what's known as high-output heart failure.
Thyroxine is a hormone the thyroid gland secretes into the bloodstream. Once in the bloodstream, thyroxine travels to the organs, like the liver and kidneys, where it is converted to its active form of triiodothyronine.
For people with heart problems: Levothyroxine can increase your risk of serious heart problems, such as heart attack, abnormal heart rhythm, and heart failure. This risk is increased if you've already had these problems. Tell your doctor if you have heart problems or a history of heart problems.
These reactions have included urticaria, pruritus, skin rash, flushing, angioedema, various GI symptoms (abdominal pain, nausea, vomiting and diarrhea), fever, arthralgia, serum sickness and wheezing. Hypersensitivity to levothyroxine itself is not known to occur.
If you suddenly stop your thyroid medication, you may be at risk of potentially serious symptoms, including: Blood pressure changes. Fatigue, muscle weakness or joint pain. Depression.
Not taking your hypothyroid or hyperthyroid medication can cause undesirable, dangerous, and even life-threatening conditions, ranging from fatigue and changes in blood pressure to death.