How to Read Your Own Blood Work: A Patient’s Guide to Hormonal Lab Results

Your blood work results arrive as a list of numbers, each flagged as normal, high, or low based on the laboratory’s reference range. You scan for anything flagged abnormal. Everything is within range. You are told you are healthy.

But the report contains more information than the flags reveal, and understanding how to read it gives you the ability to engage with your physician as an informed participant in your own care.

This guide covers the most relevant hormonal and metabolic markers, what they mean, and how to interpret them beyond the reference range.

Understanding Reference Ranges

Laboratory reference ranges are derived from the central 95 percent of values in a tested population. They define what is statistically common, not what is physiologically optimal.

A value within the reference range means you are not in the bottom 2.5 percent or the top 2.5 percent. It does not mean the value is ideal for your age, sex, or clinical situation.

A total testosterone of 9 nmol/L in a 40-year-old man is within the reference range (8.4 to 28.8 nmol/L) but is in the lowest 5 to 10 percent for his age group. A TSH of 4.0 mIU/L is within the reference range (0.4 to 4.5 mIU/L) but is associated with subclinical metabolic slowing in many individuals.

Read the number, not just the flag.

The Hormonal Markers

Total Testosterone

What it measures: All testosterone circulating in the blood, both bound and unbound.

Reference range (men): Approximately 8.4 to 28.8 nmol/L at most Ontario labs.

What to look for: A value below 15 nmol/L in a man under 50 warrants further investigation, especially if accompanied by symptoms. The range is enormous, and a value at the low end is not the same as a value at the mid-range.

Limitation: Total testosterone does not tell you how much is bioavailable. SHBG and free testosterone are needed to complete the picture.

Free Testosterone

What it measures: The 2 to 3 percent of testosterone not bound to SHBG or albumin. This is the fraction that enters cells and produces physiological effects.

What to look for: Free testosterone in the lower quartile of the reference range, especially with elevated SHBG, suggests that the bioavailable testosterone is insufficient even if the total number looks acceptable.

SHBG (Sex Hormone Binding Globulin)

What it measures: A liver-produced protein that binds testosterone (and estradiol), rendering it inactive.

What to look for: Elevated SHBG (above 50 to 60 nmol/L in men) effectively reduces the amount of free testosterone. Low SHBG (below 20 nmol/L) can indicate insulin resistance. SHBG is context: it tells you how much of the total testosterone is actually working.

Estradiol (E2)

What it measures: The primary estrogen. In men, produced via aromatase conversion of testosterone. In women, produced primarily by the ovaries.

In men: A level disproportionately elevated relative to testosterone (particularly above 150 to 180 pmol/L) suggests high aromatase activity and may contribute to symptoms.

In women: Timing matters. Estradiol fluctuates across the menstrual cycle. A value drawn on day 3 of the cycle reflects baseline ovarian function. A value drawn randomly in perimenopause may be high, low, or anything in between.

Progesterone

What it measures: The hormone produced by the corpus luteum after ovulation.

When to draw: Day 19 to 21 of the menstrual cycle, approximately 5 to 7 days after ovulation.

What to look for: A mid-luteal progesterone below 5 ng/mL suggests anovulation or inadequate luteal function. In a symptomatic perimenopausal woman, this is a meaningful finding.

The Thyroid Markers

TSH

What it measures: The pituitary’s demand signal for thyroid hormone.

Reference range: 0.4 to 4.5 mIU/L at most labs.

What to look for: Functional medicine practitioners generally consider a TSH above 2.5 mIU/L to be suboptimal in a symptomatic patient. A TSH of 3.5 with fatigue and weight gain is not the same as a TSH of 3.5 in someone who feels excellent.

Free T3

What it measures: The biologically active thyroid hormone.

What to look for: Free T3 in the lower third of the reference range often corresponds to symptoms of hypothyroidism, even when TSH is normal. This is the most actionable thyroid marker for assessing whether the body is receiving adequate active hormone.

Free T4

What it measures: The inactive prohormone produced by the thyroid gland.

What to look for: Normal free T4 with low free T3 suggests impaired T4-to-T3 conversion, which can occur with stress, inflammation, selenium deficiency, or insulin resistance.

The Metabolic Markers

Fasting Glucose

Reference range: 3.9 to 5.5 mmol/L.

What to look for: Values in the 5.2 to 5.5 range are technically normal but suggest the pancreas is already working harder to maintain glucose homeostasis. Context from fasting insulin changes the interpretation.

Fasting Insulin

What it measures: Pancreatic insulin output in the fasted state. It reflects how hard the pancreas is working to maintain glucose homeostasis in the absence of food.

Optimal range: Below 5 to 6 µIU/mL. Between 6 and 8 suggests increasing metabolic strain. Above 8 to 10 indicates early insulin resistance. Values above 12 to 15 represent significant insulin resistance.

Why it matters: This is the earliest metabolic dysfunction marker and also the most actionable. It will be abnormal years before glucose rises, and it is the upstream variable that drives many of the downstream complications of metabolic syndrome (hypertension, atherogenic lipid profile, visceral adiposity). Correcting fasting insulin addresses the root cause rather than treating the symptoms. If your lab panel includes glucose but not insulin, half the metabolic picture is missing. More critically, you miss the window where prevention is most effective.

HbA1c

What it measures: Average blood glucose over the preceding 2 to 3 months. It is a marker of glycemic control integrated across a long timeframe.

Reference range: Below 5.7% is considered normal. Below 5.0% is optimal.

Limitations: HbA1c is a valuable marker, but it has significant limitations for early detection. A person with undetected insulin resistance—elevated fasting insulin and normal glucose—will have a normal HbA1c for years. HbA1c only becomes elevated after the compensatory mechanisms of the pancreas fail and glucose begins to leak upward. It is a late-stage marker, not an early-detection tool.

What to look for: Values of 5.5 to 5.6% are in the upper normal range and may already reflect early glycemic impairment when viewed alongside elevated fasting insulin or a glucose value in the 5.2 to 5.5 range. Context from fasting insulin and HOMA-IR changes the interpretation significantly.

Lipid Panel

Total cholesterol: Less informative in isolation than its components.

LDL: Standard marker for atherogenic risk. ApoB is a more precise measure when available.

HDL: Lower values (below 1.0 mmol/L in men, below 1.3 in women) are associated with insulin resistance and metabolic syndrome.

Triglycerides: Elevated triglycerides (above 1.7 mmol/L) are a marker of insulin resistance and hepatic lipid overload. The triglyceride-to-HDL ratio (triglycerides divided by HDL, both in mmol/L) is a practical surrogate for insulin resistance. A ratio above 2.0 warrants attention.

hs-CRP

What it measures: Systemic inflammation.

Optimal: Below 1.0 mg/L. Above 3.0 mg/L is associated with significantly elevated cardiovascular risk.

What to look for: Persistent elevation suggests chronic inflammation from metabolic dysfunction, poor sleep, visceral adiposity, or other systemic sources.

The Hematological Markers

CBC with Hematocrit

Hematocrit reflects the percentage of blood volume occupied by red blood cells. Testosterone therapy increases hematocrit as a predictable effect. Baseline values above 50% in men warrant caution before starting testosterone therapy. Monitoring during therapy is essential.

Ferritin

What it measures: Iron storage.

What to look for: Low ferritin (below 30 to 50 µg/L) can cause fatigue that mimics or amplifies the effects of hormonal deficiency. This is common in menstruating women and frequently missed.

How to Use This Information

Print your lab results. Read every value, not just the flagged ones. Note where your values fall within the range: lower third, middle, upper third. Pay attention to trends across multiple draws.

Bring your questions to your physician. Ask why a value is where it is, not just whether it is normal. Ask what the optimal range would be for your age and clinical situation. Ask whether additional markers would provide useful context.

Blood work is a conversation, not a verdict. The more you understand, the more productive that conversation becomes.

Continue Reading

If you found this useful, these related articles may deepen your understanding:

• Fasting Insulin: The Blood Test That Should Be Routine
• The Blood Work You Need Before Starting Testosterone
• LifeLabs vs. Dynacare: Bloodwork in Ontario

---

Dr. Handsun Xiao is a McGill trained physician (MD, CCFP) practicing functional medicine and bioidentical hormone therapy in Toronto, with virtual consultations available to patients across Ontario. He holds advanced BHRT certification through WorldLink Medical and IFM AFMCP training. Manus Solis offers physician led BHRT consultations with custom compounding through a dedicated Ontario pharmacy partner. To learn more or book a virtual consultation, visit manussolis.ca.