Lab Tests Reference Library

TSH is secreted by the pituitary gland to control thyroid hormone production. It is the single most sensitive test for thyroid dysfunction. High TSH = hypothyroidism; low TSH = hyperthyroidism.

Free T4 is the active, unbound form of thyroxine. Low Free T4 with high TSH confirms hypothyroidism; high Free T4 with low TSH confirms hyperthyroidism.

Free T3 is the most biologically active thyroid hormone. It is useful in diagnosing T3 toxicosis and monitoring thyroid replacement therapy.

Anti-TPO antibodies attack the thyroid gland. Elevated levels indicate autoimmune thyroid disease — primarily Hashimoto's thyroiditis or Graves' disease.

FSH regulates reproductive processes. In women it stimulates ovarian follicle development; in men it stimulates sperm production. Used in fertility evaluation and menopause diagnosis.

LH triggers ovulation in women and testosterone production in men. The LH surge signals the best time for conception. Elevated LH in women may indicate PCOS or premature ovarian failure.

Prolactin is produced by the pituitary gland and stimulates breast milk production. Elevated prolactin (hyperprolactinemia) causes irregular periods, infertility, and galactorrhea.

Testosterone is the primary male sex hormone. In men, low testosterone (hypogonadism) causes fatigue, reduced libido, and muscle loss. In women, high testosterone may suggest PCOS or adrenal disorders.

Estradiol is the primary female sex hormone. Used to evaluate ovarian function, fertility, menopause, and hormonal disorders in both men and women.

Cortisol is the primary stress hormone produced by the adrenal glands. Elevated cortisol may indicate Cushing's syndrome; low cortisol may indicate Addison's disease.

AMH reflects ovarian reserve — the remaining egg supply. Used in fertility assessment and IVF planning. Low AMH indicates diminished ovarian reserve.