FSH and LH are glycoprotein hormones produced and stored in the anterior pituitary. They are under complex regulation by hypothalamic gonadotropin-releasing hormone and by gonadal sex hormones (estrogen and progesterone in females and testosterone in males). FSH acts on granulosa cells of the ovary and Sertoli cells of the testis, and LH acts on Leydig (interstitial) cells of the gonads. Normally, FSH increases occur at earlier stages of puberty, 2–4 years before LH reaches comparable levels. In males, FSH and LH are necessary for spermatozoa development and maturation. In females, follicular formation in the early stages of the menstrual cycle is stimulated by FSH; then, the midcycle surge of LH causes ovulation of the FSH-ripened ovarian follicles to occur.

This test measures the gonadotropic hormones FSH and LH and may help determine whether a gonadal deficiency is of primary origin or is due to insufficient stimulation by the pituitary hormones.

Evaluation of FSH supports other studies related to determining causes of hypothyroidism in women and endocrine dysfunction in men. In primary ovarian failure or testicular failure, FSH levels are increased. Measuring the levels of FSH and LH is of value in studying children with endocrine problems related to precocious puberty.

In the case of anovulatory fertility problems, the presence or absence of the midcycle peak can be established through a series of daily blood specimens.

See Table 6.9.

1. Obtain a 5-mL venous blood sample (red-topped tube). Serum is needed for the test. Label the specimen with the patient’s name, date and time of collection, and test(s) ordered. Place the specimen in a biohazard bag.

2. In women, record the date of last menstrual period.

3. It is important to measure both FSH and LH.

1. Decreased FSH levels occur in the following conditions:

   1. Feminizing and masculinizing ovarian tumors when FSH production is inhibited because of increased estrogen secretion

   2. Failure of hypothalamus to function properly (Kallmann syndrome)

   3. Pituitary LH or FSH deficiency

   4. Neoplasm of testes or adrenal glands that influences secretion of estrogens or androgens

   5. Polycystic ovary syndrome

   6. Hemochromatosis (increased iron in the body)

   7. Anorexia

2. Decreased FSH and LH occur in pituitary or hypothalamic failure.

3. Increased FSH levels occur in the following conditions:

   1. Turner syndrome (ovarian dysgenesis); about 50% of patients with primary amenorrhea have Turner syndrome

   2. Hypopituitarism

   3. Sheehan syndrome (postpartum hypopituitarism)

   4. Precocious puberty, either idiopathic or secondary to a CNS lesion

   5. Klinefelter syndrome

   6. Castration

   7. Alcoholism

   8. Menopause and menstrual disorders

4. Both FSH and LH are increased in the following conditions:

   1. Hypogonadism

   2. Complete testicular feminization syndrome

   3. Gonadal failure

   4. Congenital absence of testicle or testicles (anorchia)

   5. Menopause

5. Elevated basal LH with an LH/FSH ratio >2 and some increase of ovarian androgen in an essentially nonovulatory adult woman is presumptive evidence of Stein–Leventhal syndrome (polycystic ovary syndrome).

Pretest Patient Care

1. Instruct the patient regarding test purpose and procedure.

2. For women, record date of last menstrual period.

3. Follow guidelines in Chapter 1 for safe, effective, informed pretest care.

1. Recently administered radioisotopes

2. Hemolysis of blood sample

3. Estrogens or oral contraceptives, testosterone

4. Several drugs affect test outcomes; see Appendix E

5. Pregnancy

6. Heterophilic antibodies may falsely increase or decrease results