Medical treatment in patients with abnormal levels of follicle-stimulating hormone (FSH) depends on the underlying etiology. Appropriate articles are available that contain detailed discussions. However, the following points deserve mention:
In women with primary (ovarian) or secondary (pituitary) hypogonadism, hormone replacement therapy may be administered (estrogen and progesterone). However, a study by the Women's Health Initiative showed health risks from using estrogens plus progesterone in 16,608 postmenopausal women over 5.2 years of follow-up. Excess risks attributable to estrogens plus progesterone included more cardiovascular events, strokes, pulmonary emboli, and invasive breast cancers, but less risk of colorectal cancer. Hormone replacement therapy should take into account all of these factors. Also, other pituitary deficiencies (eg, thyroid, adrenal) must be corrected in the appropriate setting. 
In men with primary (testes) or secondary (pituitary) hypogonadism, testosterone replacement therapy is administered, either intramuscularly or with patches or gel. Again, other pituitary deficiencies must be corrected.
In men and women, treatment targeted at the underlying etiology may suffice. In patients with prolactinomas, medical treatment with a dopamine agonist lowers prolactin levels and may normalize FSH, LH, and testosterone/estradiol levels.  In patients with hemochromatosis, repeated phlebotomy to remove iron may reverse the gonadotropin deficiency.
A report on the use of recombinant human FSH (rhFSH) in the treatment of male infertility found that the total mobile sperm count (TMSC) rose in men with isolated FSH deficiency who received rhFSH therapy.  The investigators studied 61 infertile men, including 13 patients with isolated FSH deficiency, who received 100-150 IU of rhFSH 2-3 times per week. The TMSC rose from 6.64 (±3.27) million to 32.4 (±9.09) million in the isolated FSH deficiency patients.
A study by Zhang et al indicated that in patients with idiopathic hypogonadotropic hypogonadism, the use of sequential urinary FSH (uFSH)/human chorionic gonadotropin (hCG) injections is as effective as the administration of continual uFSH/hCG injections in inducing spermatogenesis and masculinization. 
Hormone replacement therapy
Hormone replacement therapy must be monitored carefully. Women on estrogen therapy who have an intact uterus should receive progesterone therapy to prevent endometrial hyperplasia, and they should have yearly breast examinations and mammograms as indicated.
Patients should have yearly Papanicolaou tests (Pap smears).
If vaginal bleeding occurs while on therapy, an endometrial biopsy and/or dilation and curettage should be considered to determine the presence of endometrial cancer.
Men on testosterone replacement therapy should have yearly prostate-specific antigen tests and regular rectal examinations to monitor for prostate carcinoma.
Surgery is the treatment of choice for patients with gonadotroph adenomas, adrenal tumors, or gonadal tumors, unless contraindicated for other medical reasons.
Consultation with an endocrinologist or gynecologist is frequently helpful for appropriate diagnostic evaluation and management.