Your blood work, explained.

Why your annual labs might not tell the whole story

A typical physical includes a basic metabolic panel, a cholesterol panel, and a blood count. Those are useful, but they often leave out hormones, insulin, inflammation, and the nutrients that affect how you feel and how you respond to training. Below are the markers worth knowing, grouped by what they tell you.

One important note: reference ranges vary by lab, and what's right for you depends on your age, sex, symptoms, and history. Use this guide to understand your results and ask better questions, not to diagnose yourself.

1. Hormones

Marker	What it tells you
Total testosterone	Overall testosterone level. The American Urological Association uses below 300 ng/dL as a guide for low testosterone in men, alongside symptoms. Women have much lower levels, and it matters for them too.
Free testosterone	The portion your body can actually use. Can be low even when total looks fine.
SHBG	The protein that binds testosterone. High SHBG means less free testosterone.
Estradiol	The main estrogen. Matters for bone, mood, and body composition in both men and women.
LH and FSH	Signals from the brain telling the body to make hormones. Help explain why a hormone is low. In women, FSH helps assess perimenopause.
Progesterone (women)	Varies across the cycle. Changes during perimenopause often explain sleep and mood shifts.

Prep tip: testosterone is highest in the morning, so test before about 10 a.m. A single low result is usually repeated before any decisions are made.

2. Thyroid

Marker	What it tells you
TSH	The brain's signal to the thyroid. The standard screening test.
Free T4	The main thyroid hormone in circulation.
Free T3	The active form that drives metabolism and energy.
Thyroid antibodies (TPO)	Can reveal autoimmune thyroid issues before TSH changes.

Fatigue, feeling cold, hair changes, and stubborn weight can have thyroid causes. TSH alone can miss part of the picture.

3. Blood sugar and metabolism

Marker	What it tells you
Fasting glucose	Blood sugar after fasting. Under 100 mg/dL is considered normal.
Hemoglobin A1c	Your average blood sugar over about 3 months. Under 5.7% is normal, 5.7–6.4% is prediabetes, 6.5% or higher meets the threshold for diabetes (American Diabetes Association).
Fasting insulin	Often rises years before glucose does. An early warning sign of insulin resistance.

4. Heart and cholesterol

Marker	What it tells you
Standard lipid panel	Total cholesterol, LDL, HDL, triglycerides.
ApoB	Counts the particles that actually carry cholesterol into artery walls. Many experts consider it a better risk marker than LDL alone. Lower is generally better.
Lp(a)	Largely genetic and often never tested. Worth checking once in your life. Levels around 50 mg/dL (about 125 nmol/L) or higher are generally considered elevated.

5. Inflammation

hs-CRP measures low-grade inflammation. The CDC and American Heart Association describe under 1 mg/L as lower cardiovascular risk, 1–3 as average, and above 3 as higher. A recent cold, injury, or very hard workout can raise it temporarily, so context matters.

6. Nutrients and blood health

Marker	What it tells you
Vitamin D (25-OH)	Matters for bone, muscle, and immune health. Low levels are common, especially with indoor work.
Ferritin and iron panel	Iron stores. Low ferritin is a common, overlooked cause of fatigue, especially in women and endurance athletes.
Vitamin B12	Energy and nerve health. Can run low with certain medications or plant-based diets.
CBC (complete blood count)	Red and white blood cells. Hematocrit is especially important to monitor for anyone on testosterone therapy.
CMP	Kidney and liver function, electrolytes. Hard training can temporarily raise some liver enzymes and creatinine.

How to prep for accurate results

• Morning draw, ideally before 10 a.m.
• Fasted 10–12 hours (water is fine)
• No hard training for 24–48 hours before
• Hydrate well the day before
• Tell the lab and your doctor about supplements. High-dose biotin can interfere with some hormone and thyroid tests, so ask your doctor whether to pause it beforehand.
• Retest under the same conditions so results are comparable

What to do with your results

Bring them to your doctor, along with your symptoms and goals. Good questions to ask:

• "Which of these are in range but not where you'd want them for someone my age?"
• "What lifestyle changes would move these numbers, and when should we retest?"
• "Do any of these explain how I've been feeling?"

Many of these markers respond to training, sleep, nutrition, and body composition changes. That's where coaching comes in.

This guide is educational and is not medical advice. Reference ranges vary by laboratory. Lab results should be interpreted by a licensed clinician in the context of your symptoms, history, and exam. Do not start, stop, or change any medication or supplement based on this guide.