Normal vs optimal lab results: what each range tells you

What does a normal lab range mean?

A normal range, also called a reference range, is based on the test results of large groups of healthy people. Labs set their own, so the range printed beside your result can differ from another lab’s. A test can also carry different ranges for different groups, such as men and women.

What does optimal mean in lab results?

On this site, optimal means one thing: a line a named doctor or scientist stated on video as where a result should sit. Decode draws none of these lines, and each one comes with the quote that contains its number.

People mean different things by “optimal”, so every optimal range here comes with its quote and the moment you can watch.

Normal and optimal, in the same quote

In each quote below, one speaker gives the number a lab calls normal and their own line, in the same breath:

“if your your level's under 45 it's going to affect your health even though the reference range on the lab says 16 or above is normal 45 or above should be the normal range or the optimal range”

“to the lipids I generally take a harder line on triglycerides than is typically given, so the typical reference range on triglyceride is less than 150 milligrams per deciliter — apologize, I don't know what that is in millimolar for people who are outside of the United States — I generally like to see triglycerides below 100”

“it's non-negotiable, all my patients need a uric acid below 5, even though the assay says we will consider normal up to seven point zero.”

“I like to see c-reactive protein below 1, even though most labs consider anything below 2 reasonable.”

“the insulin reference range they have is 18 as normal, and anything above that is abnormal and anything below is normal. It should be five or less.”

“you should be really low like it should be less than two nanograms per milliliter now the reference range goes up to four uh but individuals with levels below four can still have prostate cancer so it's important to to look at the progression of Rise”

Each of these tests has its own row, with the range most labs print, in the optimal blood test ranges table.

Is there always an optimal line beyond normal?

No. For most tests on this site, nobody we cite has put a number on the result, and the range your lab prints is the only line we can show you. Some sources go further and doubt the target or the test itself, including on tests where someone else drew a line:

“If your sodium is, you know, is optimal, it's normal. It's like there's a very narrow range. Or calcium. These are things in your blood test that don't really have normal or optimal. They're just — there's just one reference range.”

“If HDLs are important to the cardiovascular system — and I maintain they are — the metric HDL cholesterol is useless.”

“so our body will just continually pull from our bones to prevent magnesium levels from going below 0.7 m per liter for this reason plasma magnesium is not a good indicator of magnesium status for most healthy adults”

“There's no optimal exact level. There's no optimal level for one exact time.”

Where a second source disagrees, the optimal ranges table shows every view side by side.

Who is this page not for?

Anyone looking for a verdict on their own result. An optimal line is one person’s view for people in general. Whether it fits you is a conversation with your doctor.

Anyone looking past a result their report flags. That result goes to your doctor first.

Anyone who needs medical advice. This is a record of what named people said, with the video. It is not a diagnosis.