Dyslipidemia

What it is

Dyslipidemia is an abnormal level of lipids in the bloodstream — including elevated LDL (low-density lipoprotein) cholesterol, low HDL (high-density lipoprotein) cholesterol, elevated triglycerides, or any combination — and is one of the most significant modifiable risk factors for cardiovascular disease. Also called a lipid disorder or, colloquially, high cholesterol, dyslipidemia affects approximately 50% of adults in Western countries, including Canada, where Heart & Stroke Foundation data consistently rank it among the top preventable contributors to heart attack and stroke. The condition typically develops without any symptoms, which makes routine screening through a fasting lipid panel essential for early detection.

Hormones play a larger role in lipid regulation than most patients realize. Estrogen, thyroid hormone, insulin, cortisol, and growth hormone all influence how the liver synthesizes, processes, and clears fats from the blood. Dyslipidemia that emerges around menopause, with a new hypothyroidism diagnosis, or alongside insulin resistance often has a hormonal driver that, if treated directly, can normalize lipid levels without additional medication.

In Canada, fasting lipid panels are available through LifeLabs and Dynacare with a physician or nurse practitioner requisition, and cardiovascular risk is typically stratified using the Framingham Risk Score or the Canadian Cardiovascular Society (CCS) guidelines.

Causes and mechanism

Dyslipidemia arises from impaired lipoprotein synthesis, secretion, or clearance — driven by genetic predisposition, lifestyle factors, or underlying hormonal and metabolic conditions.

Hormonal contributors

Condition	Primary lipid effect
Hypothyroidism	Elevated LDL and total cholesterol; impaired LDL receptor activity; present in up to 90% of untreated cases
Menopause / estrogen deficiency	LDL rises ~10–15%; HDL may fall as estrogen declines
Insulin resistance / type 2 diabetes	Elevated triglycerides, low HDL, small dense LDL — the most atherogenic pattern
Cushing's syndrome	Elevated LDL, total cholesterol, and triglycerides from excess cortisol
PCOS	Insulin resistance drives the same atherogenic pattern as type 2 diabetes
Male hypogonadism / androgen deprivation therapy	Elevated LDL and triglycerides, reduced HDL

Lifestyle contributors include a diet high in saturated and trans fats, physical inactivity, obesity, excess alcohol, and smoking. Familial hypercholesterolemia (FH) — a genetic condition affecting roughly 1 in 250 Canadians — causes severely elevated LDL from birth and requires early identification and aggressive treatment.

Symptoms and diagnosis

Dyslipidemia causes no symptoms in the vast majority of people. In rare, severe cases, visible signs may appear: xanthomas (fatty deposits under the skin or in tendons), xanthelasma (yellowish deposits around the eyelids), or corneal arcus (a pale ring around the iris in younger individuals). These are more common in familial hypercholesterolemia.

Diagnosis involves:

1. Fasting lipid panel — measures total cholesterol, LDL, HDL, and triglycerides. Canadian guidelines generally target LDL below 2.0 mmol/L in high-risk patients.
2. Cardiovascular risk assessment — the Framingham Risk Score or CCS risk calculator determines 10-year cardiovascular risk and guides treatment intensity.
3. TSH — to rule out hypothyroidism, which is present in up to 90% of untreated cases and directly elevates LDL.
4. Fasting glucose and HbA1c — to assess for insulin resistance or diabetes.
5. Liver function tests — recommended before and during statin therapy.

Treatment options

Treatment combines lifestyle modification with medication where indicated, and — critically — addresses any underlying hormonal cause.

Lifestyle

• Reduce saturated and trans fat intake; increase dietary fibre, omega-3 fatty acids, and plant sterols
• Regular aerobic exercise raises HDL and lowers triglycerides; its effect on LDL is more modest (approximately 5–10% reduction)
• Weight loss improves all lipid parameters
• Smoking cessation and limiting alcohol intake

Medications

• Statins (atorvastatin, rosuvastatin): first-line for elevated LDL; reduce LDL by 40–60% and are covered under most provincial drug benefit formularies in Canada for eligible patients
• Ezetimibe: reduces intestinal cholesterol absorption; added when statin therapy alone does not reach LDL targets
• PCSK9 inhibitors (evolocumab, alirocumab): injectable agents that dramatically lower LDL; used in high-risk patients or familial hypercholesterolemia; coverage varies by province under the pan-Canadian Pharmaceutical Alliance agreements
• Fibrates (fenofibrate): primarily for significantly elevated triglycerides
• High-dose omega-3 fatty acids: for severely elevated triglycerides (above 10 mmol/L, where pancreatitis risk rises)

Treating the underlying hormonal cause

• Levothyroxine for hypothyroidism typically normalizes lipid levels without additional lipid-lowering medication
• Improved glycemic control in diabetes significantly reduces the atherogenic lipid pattern
• Menopausal hormone therapy (MHT) can improve the post-menopausal lipid shift in appropriately selected women; the SOGC's 2023 menopause guidelines address this in the context of individualized cardiovascular risk assessment

When to see a clinician in Canada

Request a fasting lipid panel if you:

• Are 40 or older and have never had a cholesterol check (or are younger with cardiovascular risk factors)
• Have a family history of early cardiovascular disease or familial hypercholesterolemia
• Have diabetes, hypertension, obesity, PCOS, or a known thyroid condition
• Have been told your cholesterol is elevated but have not had a formal cardiovascular risk assessment

A family physician, internist, or endocrinologist can order testing through LifeLabs or Dynacare and apply the CCS risk framework to determine whether lifestyle changes alone are sufficient or whether medication is warranted. Canadians in provinces with telehealth coverage can also access lipid assessment through platforms such as Maple, Felix, or Cleo, though in-person follow-up is advisable for complex or high-risk cases.

Limitations and open questions

Research is still emerging on several aspects of dyslipidemia management. The cardiovascular benefit of raising HDL pharmacologically has not been clearly demonstrated in clinical trials, despite low HDL being an established risk marker. The optimal LDL target for lower-risk patients remains debated, and Canadian and American guidelines differ modestly on thresholds. The role of lipoprotein(a) — an independent genetic risk factor — is increasingly recognized, but Health Canada has not yet approved specific Lp(a)-lowering therapies, and routine screening is not universally recommended in Canadian primary care. Evidence on the net cardiovascular effect of menopausal hormone therapy remains nuanced: timing relative to menopause onset, route of administration, and individual risk profile all appear to matter, and the SOGC acknowledges that guidance in this area continues to evolve. The clinical significance of statin-related reductions in sex hormone levels is also not well established.