Hormone Testing: What Labs to Request and How to Interpret Them

You've decided your hormones need investigating. Maybe you're dealing with fatigue that won't quit, weight that won't budge, mood changes you can't explain, or symptoms that don't add up. You want labs — but which labs? When? And what do the results actually mean?

Most people either get too few tests (a TSH and nothing else) or a kitchen-sink panel from a wellness clinic with no context for interpreting the 40 values that come back. Neither approach is particularly useful. What works is targeted testing, done at the right time, interpreted with clinical judgment — not just reference ranges.

The Basics: When and How to Test

Timing matters for hormone testing, and it's one of the most common errors:

Time of day:

• Cortisol — Morning (8-9 AM), when it should be at its highest. A random afternoon cortisol is nearly useless
• Testosterone (men) — Morning (before 10 AM), fasting. Testosterone peaks in the early morning and declines throughout the day. An afternoon draw can read 20-30% lower than morning
• Testosterone (women) — Less circadian variation, but morning is still preferred
• Insulin — Fasting (10-12 hours)
• Growth hormone — Highly variable; usually tested through IGF-1 (more stable marker) rather than direct GH measurement

Menstrual cycle timing (premenopausal women):

• Day 3 labs (follicular phase): FSH, LH, estradiol — baseline hormone assessment
• Day 21 labs (mid-luteal phase): Progesterone — confirms ovulation and adequate progesterone production
• Any time: TSH, free T4, free T3, thyroid antibodies, testosterone, DHEA-S, cortisol, insulin

Important testing conditions:

• Fasting (10-12 hours) for metabolic labs — glucose, insulin, lipids
• Well-rested — acute sleep deprivation affects hormone levels
• Not acutely ill — illness temporarily disrupts hormonal balance
• Note any medications — oral contraceptives, biotin supplements, thyroid medication, and other drugs can affect test results

The Essential Panels

Thyroid Panel

The minimum: TSH, free T4, free T3

The complete panel:

• TSH — Screening test. High = underactive thyroid. Low = overactive thyroid.
• Free T4 — The unbound, available storage form of thyroid hormone
• Free T3 — The active hormone. Low free T3 with normal TSH suggests a conversion problem
• Reverse T3 — An inactive metabolite. Elevated rT3 can block T3 at cellular receptors, causing hypothyroid symptoms despite normal-looking standard labs
• TPO antibodies — Positive in 90-95% of Hashimoto's thyroiditis. This is how you catch autoimmune thyroid disease early
• Thyroglobulin antibodies — Another Hashimoto's marker

Why this matters: A TSH of 2.5 with low free T3, elevated reverse T3, and positive TPO antibodies tells a very different story than a TSH of 2.5 with everything else normal. Without the full panel, you're reading one page of a novel.

Sex Hormones (Women)

Essential:

• Estradiol (E2) — Day 3 for baseline, day 21 for luteal assessment
• Progesterone — Day 21. Below 5 ng/mL suggests anovulation or inadequate luteal function; optimal mid-luteal levels are typically 10-25 ng/mL
• FSH and LH — Day 3. Elevated FSH suggests declining ovarian reserve. LH:FSH ratio greater than 2:1 may suggest PCOS
• Testosterone (total and free) — Elevated in PCOS; low in perimenopausal or menopausal women experiencing low libido and fatigue
• DHEA-S — Adrenal androgen. Elevated in PCOS or adrenal hyperplasia; low in adrenal insufficiency or chronic stress
• SHBG — Low SHBG increases free hormone levels; elevated SHBG (often from oral contraceptives) can reduce available hormones

Additional when indicated:

• AMH (anti-Mullerian hormone) — Ovarian reserve marker. Any time in the cycle.
• 17-hydroxyprogesterone — To rule out congenital adrenal hyperplasia (especially with elevated testosterone)
• Prolactin — Elevated levels can cause menstrual irregularity and amenorrhea

Sex Hormones (Men)

Essential:

• Total testosterone — Morning, fasting. Below 300 ng/dL on two separate draws suggests hypogonadism
• Free testosterone — More reflective of what's biologically available. Can be directly measured or calculated from total T and SHBG
• SHBG — High SHBG means less free testosterone, even with normal total T. Common with aging, liver disease, and hyperthyroidism
• LH and FSH — Distinguish primary (testicular) from secondary (pituitary/hypothalamic) hypogonadism
• Estradiol — Important even in men. Elevated estradiol causes gynecomastia, mood changes, and water retention. Relevant for monitoring on TRT
• Prolactin — Elevated levels can suppress testosterone and cause symptoms. Can indicate pituitary issues

Additional:

• PSA — Baseline before TRT in men over 40
• Hematocrit/hemoglobin — Baseline and monitoring on TRT
• Albumin — For accurate bioavailable testosterone calculation

Metabolic Hormones

Essential:

• Fasting insulin — This is arguably the most underordered test in medicine. It detects insulin resistance years before fasting glucose or HbA1c become abnormal. Optimal fasting insulin: under 7 uIU/mL. Many labs list the reference range as up to 25, which includes people with significant insulin resistance
• Fasting glucose — Normal: under 100 mg/dL. Pre-diabetic: 100-125. But glucose is a late marker — by the time it's elevated, insulin resistance has been present for years
• HbA1c — 3-month average blood sugar. Normal: under 5.7%. Pre-diabetic: 5.7-6.4%. Useful but less sensitive than fasting insulin for early detection
• HOMA-IR — Calculated from fasting glucose and fasting insulin. A more sensitive marker of insulin resistance than either alone

Why metabolic labs matter for hormones: Insulin resistance drives hormonal disruption in multiple directions — increases estrogen (through aromatase activity in fat tissue), decreases SHBG (freeing more hormones but in a dysregulated way), increases testosterone in women (PCOS mechanism), and decreases testosterone in men.

Adrenal Hormones

Essential:

• Cortisol — Morning serum cortisol for screening. Salivary cortisol at four points throughout the day for HPA axis assessment
• DHEA-S — Adrenal function marker. Declines with age but should be assessed when fatigue or hormonal symptoms are present

When indicated:

• ACTH — If cortisol is abnormal, ACTH helps localize the problem (adrenal vs. pituitary)
• Aldosterone and renin — If blood pressure is abnormal or electrolyte imbalances are present
• 24-hour urinary cortisol — For suspected Cushing's syndrome

Interpreting Your Results

Reference Ranges vs. Optimal Ranges

Lab reference ranges are derived from the statistical distribution of the testing population — typically the middle 95%. This means 2.5% of healthy people will fall outside the "normal" range on any given test, and people with subclinical dysfunction are included in the reference population.

The practical problem: A result that falls within the reference range isn't necessarily optimal for you. A TSH of 4.0 is "normal" by most lab standards but may cause symptoms in a person whose optimal TSH is 1.5.

Functional ranges — tighter ranges based on optimal function rather than population averages — are used by many integrative and functional medicine practitioners:

| Test | Lab Reference Range | Functional Optimal Range |

|------|---------------------|--------------------------|

| TSH | 0.4-4.5 mIU/L | 0.5-2.5 mIU/L |

| Free T4 | 0.8-1.8 ng/dL | 1.0-1.5 ng/dL |

| Free T3 | 2.3-4.2 pg/mL | 3.0-4.0 pg/mL |

| Fasting insulin | 2-25 uIU/mL | Under 7 uIU/mL |

| Vitamin D | 30-100 ng/mL | 50-80 ng/mL |

| Ferritin | 12-150 ng/mL (women) | 50-100 ng/mL |

Context Matters More Than Numbers

A single lab value in isolation tells you very little. What matters is:

• The pattern across related tests — Low free T3 with normal TSH and elevated rT3 suggests a conversion problem. Low free T3 with high TSH suggests primary hypothyroidism. Same low T3, completely different situations.
• Your symptoms — Lab values should be interpreted alongside your clinical presentation. Treating a number without symptoms — or ignoring symptoms because the number is "normal" — are both errors.
• Trends over time — A testosterone of 400 ng/dL in a man who was at 700 two years ago is clinically meaningful, even though both values are "normal."
• Interactions between systems — Thyroid, adrenal, and sex hormones are interconnected. Treating one without understanding the others often produces incomplete results.

Common Patterns and What They Mean

Pattern 1: Fatigue, weight gain, cold intolerance

→ Check: Full thyroid panel, fasting insulin, cortisol, iron/ferritin, vitamin D

Pattern 2: Low libido, mood changes, fatigue (men)

→ Check: Total and free testosterone, SHBG, LH/FSH, estradiol, prolactin, thyroid, metabolic panel

Pattern 3: Irregular cycles, acne, weight gain (women)

→ Check: Total and free testosterone, DHEA-S, LH/FSH (day 3), fasting insulin, thyroid, prolactin

Pattern 4: Perimenopausal symptoms

→ Check: FSH, estradiol, progesterone (day 21), thyroid, cortisol, DHEA-S

Pattern 5: Chronic fatigue, stress, brain fog

→ Check: Cortisol (AM and 4-point salivary), DHEA-S, thyroid panel, fasting insulin, CBC, ferritin, vitamin D, B12

Getting the Right Tests

The biggest barrier to proper hormone testing isn't the tests themselves — it's getting someone to order the right ones and interpret them in context. Many patients are told "your labs are normal" when a deeper look would reveal actionable findings.

At CORAL, Dr. Kim orders comprehensive hormone panels tailored to your symptoms and clinical picture. The goal isn't to run every test available — it's to run the right tests, at the right time, and interpret them with clinical judgment rather than just checking against reference ranges.

Start your evaluation at [coral.clinic/start](https://coral.clinic/start). You'll get the labs you actually need and an interpretation that goes beyond "everything looks normal."