Statin Myopathy – Part 1
It’s a common scenario, you walk out of a doctors office with a plan of care that has you all pumped to improve your health – only to realize you can’t carry it through. As physicians we often frown at these “excuses” and label patients as noncompliant rather than address the barriers to therapy. If you can’t make it to a physical therapist for your neck strain, we need to work on an alternative plan of care – not simply expect a single mom to miss work because we said so. There is usually more then one way to skin a cat (no cats were skinned in the writing of this post). Similarly, as a patient, if you feel you are having a side effect of a medication, talk to your doctor – it may be more common then you think – and likely have an easy fix. In today’s post I am going to address a common side effect of one of the most commonly prescribed medications known to reduce cardiovascular disease – Statins.
Statins, as they have come to be known, are the common name to a group of cholesterol reducing medications called HMG Co-A reductase inhibitors. They block one of the essential enzymes in the making of cholesterol and over time have come to be known to have more beneficial effects in reducing artery plaque and cardiovascular disease above and beyond the reduction in bad cholesterol.
Unfortunately many of us who are prescribed statins are intolerant to it. The most common side effect being muscle aches, known as myalgia – and uncommonly actual inflammation of the muscle, known as myositis. These are grouped together as myopathy. Myalgia often leaves patients and doctors looking for less beneficial alternatives. I am not going to talk about alternatives in this post, that can of worm is best left to another post.
There are several suspected causes of statin induce myopathy, but there are two that I see most commonly in practice, both fortunately, are easy to rectify. These two have their own clinical sequelae and therefore are equally important to correct, regardless of statin use. These are:
- Low thyroid function, known as hypothyroidism
- Low vitamin D, known as either hypovitaminosis D or simply as vitamin D deficiency
Hypothyroidism is a known cause of statin myopathy, but there is very limited information in the medical literature about low vitamin D. Both are under diagnosed, but easy to treat. I will discuss my thoughts on the former in this post, and the latter in Part 2.
Hypothyroid
With patients with known hypothyroid state, decisions are easy. As a rule I do not initiate statin therapy, until I have their thyroid function optimized. There are rare exceptions – I would not withhold statins from someone who is at exceptional risk of a cardiovascular event (such as an impending heart attack).
There are two reasons I would fix their thyroid function before statin therapy.
- Low thyroid state is associated with low metabolism, which may cause your lipid panel to look, well, quite pathetic. With improved metabolism from optimal therapy for hypothyroidism, the lipids may look better. As a result, we will have a real baseline to compare to when we start statin therapy, or in some cases, it may look so much better, statins may not be needed!
- If their thyroid function is low, there is a pretty good chance they will have muscle aches with a statin, and probably discontinue therapy and subsequently be labelled as statin intolerant.
“My hypothyroid is subclinical – so I don’t need meds.”
Patients are often diagnosed with subclinical hypothyroid when they have slightly abnormal function and no symptoms. Sometimes they have borderline thyroid function (barely within range) with minimal symptoms, and a decision is made not to treat unless the lab tests look definitely abnormal or if symptoms are at least moderate. I find that many of these patient are susceptible to statin induced myopathy. Not uncommonly, if a previous decision was made to watch thyroid function before considering therapy, statin myopathy would quickly change my mind. If your muscle aches on a statin – and your thyroid function is less than perfect – you get a trial of thyroid replacement therapy (TRT). I have found that although I previously thought they may have had subclinical hypothyroidism, these patients often report a signifiant improvement in their sense of well being and quality of life with TRT. This is usually followed by the terrible guilt of not initiating therapy sooner – their hypothyroidism was probably not as “sub” clinical as I had thought.
Coming up next in Part 2 – Low vitamin D, and its association with statin myopathy, stay tuned.