What is an Optimal Range and What Does it Mean?

Standard Canadian labs determine “normal” ranges based on Canadian averages to help determine risks of disease. What labs don’t include are the science-backed ranges that are linked to optimal health. As part of your Longevity test, you will see where your biomarkers fall compared to normal and optimal ranges, so that you can easily identify opportunities to optimize your health. 

What is a normal range?

A normal range in blood testing reflects what is considered statistically typical in the general population; usually 95% of the population. There are different ranges depending on the test being done. If your blood test result falls within the normal range, it generally means that you don’t have an immediate clinical issue. If your results fall outside the range, your practitioner will identify what may have affected your results by looking at other information about your health. 

What is an optimal range?

An optimal range reflects the ideal range your biomarkers should be for peak function and wellbeing. The optimal ranges at Felix are determined by what’s scientifically and clinically shown to support better health and longevity. Some of these ranges may fall within normal ranges, but reflect a narrower target that is associated with optimal health, rather than just a lower risk of disease. 

How optimal ranges are determined

Hemogobin A1c (HbA1c)

Optimal range: 4.3 - 5.5%

Hemeglobin A1c, also known as HbA1c or A1c, is a blood test that reflects the average blood sugar levels over the past 2 to 3 months. It measures the percentage of glucose attached to hemoglobin in red blood cells. This test helps detect whether blood sugar levels have remained elevated over time, which is especially useful for diagnosing and monitoring diabetes. 

Research shows that higher HbA1c levels are linked to a higher risk of developing prediabetes, starting from 5.5%. There is also evidence that indicates that the risk of cardiovascular disease and mortality increases when HbA1c levels are above 5%. Thus, Felix has determined that a range of 4.3 - 5.5% to be optimal.

Alanine Aminotransferase (ALT)

Optimal range for females: 0 - 25 U/L

Optimal range for males: 0 - 33 U/L

Alanine aminotransferase (ALT) is an enzyme found in the liver. It is used to detect inflammation and liver damage. Elevated ALT levels in the blood indicate liver cell damage and may be a sign of liver disease, metabolic health concerns, or other conditions.

Over the years, what’s considered “normal” ALT levels has changed. Lab reference ranges are typically based on average values from the general population. However, as more people have become less healthy over time, ALT averages have slowly increased. Knowing this, and the connection between increased mortality risk and seemingly small elevations of ALT, the American College of Gastroenterology now recommends a maximum of 33U/L for males, and 25U/L for females. 

Lipoprotein(a) (Lp(a))

Optimal range: <75 nmol/L

Liproprotein(a), or Lp(a), is a type of cholesterol particle in the blood. What makes it important is that it is more likely to stick to artery walls than any other type of cholesterol, which can also make blood more likely to clot. Because of this, high levels of Lp(a) are linked to a greater risk of heart problems. Unlike other cholesterol markers, Lp(a) levels are mostly determined by genetics. 

An estimated 1 in 5 people worldwide have high levels of Lp(a), which increases their risk of cardiovascular diseases. The health risks that come with an elevated Lp(a) typically become more significant after the age of 50. Most practitioners recommend getting it tested at least once in your life, especially if you have a family history of heart disease. However for women, Lp(a) levels may change after menopause, so it’s recommended to be tested twice: once before menopause and once after, unless the first test happens after menopause. 

Apolipoprotein B (ApoB)

Optimal range: <0.8g/L

Apolipoprotein (ApoB) is a key protein found in certain types of cholesterol particles, like LDL-C, which are linked to higher risk of cardiovascular disease and atherosclerosis (hardening of the arteries). ApoB makes up to 20-25% of the total weight of these particles. Measuring ApoB provides a more reliable and precise way of measuring levels of these types of cholesterol in the blood compared to LDL-C since it does not vary as much after eating or between tests. 

Based on guidelines from the European Atherosclerosis Society, American Heart Association, and Canadian Cardiovascular Society, Felix has defined optimal levels as less than 0.8g/L. Some guidelines have suggested ApoB targets to be 0.65g/L for those who are at a higher risk of heart attacks or strokes, though reaching this level usually requires medication. 

Estimated Glomerular Filtration Rate (eGFR)

Optimal range: >90 mL/min/1.73m²

Estimated Glomerular Filtration Rate (eGFR) is a measure of how well the kidneys are functioning by estimating how effectively they filter waste from the blood. Having a low eGFR may mean your kidneys aren’t functioning as well as they should. This is important because chronic kidney disease (CKD) affects about 4 million Canadians, yet many are unaware of it since CKD often develops without any symptoms. Because of this, the Canadian Society of Nephrology recommends testing for CKD in higher risk populations, such as patients with diabetes, hypertension, heart disease, or those of indigenous descent. 

It’s also worth noting that eGFR naturally declines with age. Some labs even consider 60 mL/min/1.73m² as a normal lower limit. However, any result below 90 mL/min/1.73m² indicates reduced kidney function, which is why Felix has determined this to be the optimal range. 

Low-density lipoprotein cholesterol (LDL-C)

Optimal range: <1.8mmol/L

Low-density lipoprotein cholesterol (LDL-C), more commonly known as “bad” cholesterol, helps to carry cholesterol from the liver to different parts of the body. However if there’s too much LDL-C in the blood, cholesterol can build up on the walls of arteries, a condition known as atherosclerosis. Over time, this buildup forms plaques that narrow and harden the arteries, increasing the risk of heart attacks, strokes, and other heart-related conditions. The Global Burden of Disease study found that having high LDL-C levels is the third-highest contributor to cardiovascular disease in the world. 

For the general population, the Canadian Cardiovascular Society recommends aiming for LDL-C levels below 3.5mmol/L. For those aged 40 to 75 who are at a higher risk of cardiovascular disease or have previously had a heart attack or stroke, they recommend aiming for LDL-C levels to be below 2mmol/L. Achieving this lower level often involves medication.

Total testosterone

Optimal range for males: ≥15nmol/L

Testosterone is a hormone that is mainly produced by the sex organs. It plays a central role in male health such as supporting libido, muscle mass, mood, red blood cell production, energy levels, and overall vitality. When testosterone levels drop in men, symptoms may include low libido, fatigue, erectile dysfunction, reduced strength and hair loss. 

Vitamin D

Optimal range: >100nmol/L

Vitamin D, commonly known as the “sunshine vitamin”, is a fat-soluble vitamin that plays many key roles in the body. It helps the body to absorb calcium and phosphorus, which is used to build and maintain strong bones and teeth. It supports the immune system by helping the body to fend off infections, and may also influence brain and heart health. 

Low vitamin D levels can lead to weakened bones and an increased risk of fractures. It may also lead to a weakened immune system, making the body more susceptible to infections. 

Vitamin B12

Optimal range: >400 pmol/L

Vitamin B12 is a water-soluble vitamin that’s essential for making red blood cells, maintaining the health of nerve cells, aiding in the synthesis of DNA and genetic material, and helping to convert food into energy. 

Low vitamin B12 levels can cause symptoms that affect the brain and nervous system. If the body doesn’t have enough vitamin B12, it is unable to produce enough healthy red blood cells which can lead to anemia.

Ferritin

Optimal range for females: 100 - 200ug/L

Optimal range for males: 100 - 300ug/L

Ferritin is a protein that stores iron in the body. Low ferritin may be a sign of iron deficiency anemia. Levels below 12 - 18ug/L indicate iron deficiency, but levels below 30ug/L are considered an early warning sign. On the other hand, high ferritin suggests hemochromatosis (a condition where the body stores too much iron), liver problems, kidney diseases, or metabolic syndrome. Ferritin also increases in response to inflammation in the body, so it’s now being recognized as a marker linked to metabolic disorder. 

Ferritin levels should be looked at alongside a full iron panel and your personal health history, because ferritin alone doesn’t always give a full picture of iron status. 

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