Evidence-Based Supplement & Herb Guides

Thyroid Antibody Panel: TPOAb, TgAb, TRAb, TSI, and Results

Understand TPOAb, TgAb, TRAb, and TSI results, including Hashimoto and Graves patterns, normal thyroid function, pregnancy, and cancer follow-up.

A thyroid antibody panel looks for immune proteins that react with the thyroid gland or its hormone-making machinery. The four names most often seen...

Thyroid Function Test Panel: TSH, Free T4, Free T3, Thyroid Antibodies, and Results

Learn how TSH, free T4, free T3, and thyroid antibodies fit together, what common result patterns mean, and when repeat testing or follow-up is needed.

A thyroid function test panel combines blood tests that show how the pituitary gland and thyroid are communicating. TSH is usually the starting test,...

Thyroid Hormone Replacement Monitoring Test: TSH, Free T4, Levothyroxine Dose, and Results

Learn how TSH and free T4 guide levothyroxine dosing, when to retest, and how missed doses, absorption, pregnancy, and interactions affect results.

Thyroid hormone replacement monitoring checks whether a levothyroxine dose is supplying enough T4 without causing excess. For most adults with primary hypothyroidism, TSH is...

Thyroid Peroxidase Antibody (TPOAb) Test: Hashimoto Thyroiditis, Graves Disease, and Results

Understand positive and negative TPOAb results, Hashimoto and Graves associations, normal thyroid function, pregnancy risks, and when follow-up is needed.

The thyroid peroxidase antibody test detects immune proteins directed against thyroid peroxidase, an enzyme the thyroid uses to make T4 and T3. A positive...

Thyroid Tests in Pregnancy: TSH, Free T4, TPOAb, Trimester Ranges, and Results

Understand pregnancy TSH, free T4, TPOAb, and TRAb results, trimester ranges, hypothyroid and hyperthyroid patterns, treatment monitoring, and postpartum care.

Thyroid testing in pregnancy usually begins with TSH and adds free T4 when TSH is outside the pregnancy-appropriate range or thyroid disease is strongly...

Thyroid-Stimulating Hormone (TSH) Test: High, Low, Normal Range, and Thyroid Function Results

Understand high, low, and normal TSH results, how free T4 and T3 change the meaning, and when repeat testing, treatment review, or urgent care is needed.

The thyroid-stimulating hormone test measures TSH, a pituitary hormone that tells the thyroid how much T4 and T3 to make. It is usually the...

Thyroid-Stimulating Immunoglobulin (TSI) Test: Graves Disease, Positive Results, and Meaning

Understand positive, negative, and borderline TSI results, how TSI differs from TRAb, and how the test guides Graves diagnosis, relapse assessment, and pregnancy care.

The thyroid-stimulating immunoglobulin test looks for antibodies that activate the thyroid’s TSH receptor. These stimulating antibodies can make the gland produce excessive T4 and...

Thyroxine-Binding Globulin (TBG) Test: High, Low, Normal Range, and Thyroid Hormones

Understand what a TBG blood test measures, why high or low levels alter total T4 and T3, common causes, normal ranges, and the right follow-up tests.

A thyroxine-binding globulin test measures the blood protein that carries most circulating T4 and T3. It is mainly used when total thyroid hormone results...

Total T3 (Triiodothyronine) Test: High, Low, Normal Range, and Hyperthyroidism Results

Learn how a total T3 blood test detects T3-predominant hyperthyroidism, what high or low results mean, typical ranges, interferences, and follow-up steps.

A total T3 test measures all triiodothyronine in the blood, including hormone attached to carrier proteins and the very small free portion. It is...

Total T4 (Thyroxine) Test: High, Low, Normal Range, and Thyroid Function

Understand total T4 testing, including normal ranges, high and low causes, binding-protein effects, pregnancy and newborn use, assay limits, and follow-up.

A total T4 test measures all thyroxine in the blood, including hormone bound to transport proteins and the small free fraction. T4 is the...

TSH Receptor Antibody (TRAb) Test: Graves Disease, Hyperthyroidism, and Results

Learn how TRAb testing confirms Graves disease, how positive or negative results are interpreted, how assays differ, and why TRAb matters in relapse and pregnancy.

A TSH receptor antibody test detects autoantibodies that attach to the thyroid’s TSH receptor. It is most often used to confirm Graves disease, the...

TSH With Reflex to Free T4 Test: Thyroid Screening, Abnormal Results, and Meaning

Understand how TSH with reflex to free T4 works, what abnormal result combinations mean, when the algorithm can miss disease, and which follow-up tests help.

A TSH with reflex to free T4 test is a laboratory algorithm rather than a single combined measurement. The laboratory measures thyroid-stimulating hormone first....

17-Hydroxyprogesterone (17-OHP) Test: Congenital Adrenal Hyperplasia, PCOS, and Results

Understand the 17-OHP test, common ranges, CAH and PCOS causes of high results, ACTH stimulation, timing, and the next steps after an abnormal value.

The 17-hydroxyprogesterone (17-OHP) test measures a steroid made mainly in the adrenal glands and, to a smaller extent, the ovaries and testes. Its main...

Androstenedione Blood Test: High, Low, PCOS, Adrenal, and Fertility Results

Learn what an androstenedione blood test shows, why levels may be high or low, how PCOS and adrenal causes differ, and which follow-up tests help.

An androstenedione blood test measures a weak androgen made by the adrenal glands and gonads. The body can convert it into testosterone or estrogens,...

Anti-Mullerian Hormone (AMH) Test: Ovarian Reserve, Fertility, and Results

Understand AMH testing for ovarian reserve, fertility treatment response, high and low results, PCOS, age effects, limitations, and useful next steps.

The anti-Müllerian hormone (AMH) test estimates the pool of small growing ovarian follicles and is widely used to predict how the ovaries may respond...

Bioavailable Testosterone Test: High, Low, Normal Range, and Results

Understand bioavailable testosterone, how SHBG and albumin affect results, causes of high or low levels, testing methods, and safe follow-up steps.

A bioavailable testosterone test estimates the testosterone that is not tightly bound to sex hormone-binding globulin (SHBG). It includes free testosterone plus testosterone loosely...

Day 21 Progesterone Test: Ovulation Confirmation, Luteal Phase, Normal Range, and Results

Learn when to schedule a day 21 progesterone test, what levels can confirm ovulation, why low results occur, and why one value cannot grade luteal quality.

A “day 21” progesterone test checks whether ovulation likely occurred by measuring progesterone during the luteal phase. The name assumes a 28-day cycle with...

Dehydroepiandrosterone Sulfate (DHEA-S) Test: High, Low, Normal Range, and Results

Understand the DHEA-S test, age-specific ranges, adrenal causes of high or low results, links with PCOS and CAH, and the follow-up tests that help.

A dehydroepiandrosterone sulfate (DHEA-S) test measures the most abundant circulating adrenal androgen. Because the adrenal glands produce nearly all DHEA-S, the result helps identify...

Delayed Puberty Hormone Test Panel: LH, FSH, Estradiol, Testosterone, and Results

Understand delayed puberty hormone testing with LH, FSH, estradiol, and testosterone, common result patterns, age cutoffs, causes, and next steps.

A delayed puberty hormone panel measures signals from the pituitary gland and sex hormones from the ovaries or testes to help explain why puberty...

Estradiol (E2) Test: High, Low, Normal Range, Fertility, and Menopause Results

Understand estradiol testing, cycle and menopause ranges, causes of high or low E2, fertility uses, related hormone patterns, and next steps after results.

An estradiol (E2) test measures the most active estrogen during the reproductive years. It helps evaluate menstrual changes, fertility treatment, ovarian function, puberty, menopause-related...