CANCER) in men, OSTEOPOROSISand BREAST CANCER
prevention in women (estrogen analogs), and fer-
tility treatments in women.
Estrogen products were a mainstay of therapy
(alone or in combination with PROGESTERONE) to
relieve the discomforts of menopause for much of
the latter half of the 20th century. Research in the
early 2000s demonstrated significant risks with
routine hormone replacement therapy (HRT),
however, resulting in a change in medical practice
to use such products within narrow therapeutic
guidelines and for the shortest amount of time
possible to achieve a therapeutic result.
For further discussion of estrogen within the
context of the endocrine system’s structure and
function please see the overview section “The
Endocrine System.”
See also CHLOASMA; ENDOMETRIAL CANCER; FOLLI-
CLE-STIMULATING HORMONE(FSH); GYNECOMASTIA; HOR-
MONE THERAPY; HYPOGONADISM; HYPOTHYROIDISM;
INFERTILITY; LUTEINIZING HORMONE(LH); MENSTRUATION;
PHYTOESTROGENS; POLYCYSTIC OVARY SYNDROME(PCOS);
TESTOSTERONE; THYROID GLAND.
euthyroid sick syndrome A circumstance in
which BLOODtests show irregular thyroid HORMONE
levels in the blood but hypothalamic, pituitary,
and thyroid functions are all normal. Euthyroid
sick syndrome typically accompanies a severe
acute illness or chronic condition. Many medica-
tions interfere with thyroid function, altering thy-
roid hormone levels in the blood. Because the
body experiences significant physiologic stress
with severe illness, many of the body’s natural
hormonal responses have the consequence of
altering thyroid hormone levels.
Typically there are no symptoms of hypothy-
roidism with euthyroid sick syndrome, though the
symptoms of the health condition may make this
difficult to assess. Declining thyroid hormone lev-
els, measured through blood tests, provide impor-
tant insight into the overall crisis state the body is
experiencing. There appears to be no benefit in
treating euthyroid sick syndrome with replace-
ment thyroid hormones, so most doctors choose a
course of watchful waiting in regard to thyroid
function and focus therapeutic efforts on the
causative condition. Thyroid hormone levels grad-
ually return to normal as the person recovers from
the underlying acute illness or when the chronic
condition improves.CONDITIONS THAT MAY RESULT IN
EUTHYROID SICK SYNDROME
BONE MARROW TRANSPLANTATION BURNS
CANCER CARDIOMYOPATHY
chronic CIRRHOSIS CHRONIC OBSTRUCTIVE
DIABETES PULMONARY DISEASE(COPD)
GLOMERULOSCLEROSIS GLOMERULONEPHRITIS
INFLAMMATORY BOWEL DISEASE(IBD) HEART FAILURE
ISCHEMIC HEART DISEASE(IHD) major surgery
MYOCARDIAL INFARCTION ORGAN TRANSPLANTATION
PANCREATITIS POLYGLANDULAR DEFICIENCY
RENAL FAILURE SYNDROME
SARCOIDOSIS severe GASTROENTERITIS
SYSTEMIC LUPUS ERYTHEMATOSUS(SLE) major traumaSee also GOITER; HYPERTHYROIDISM;THYROID GLAND.follicle-stimulating hormone (FSH) A peptide
HORMONEthe anterior lobe of the PITUITARY GLAND
secretes in response to stimulation from the HYPO-
THALAMUS’s release of GONADOTROPIN-STIMULATING
HORMONE(GNHR). In women, FSH stimulates the
follicles in the OVARIESto bring eggs (OVA) to matu-
rity. In men, FSH stimulates growth of cells in the
TESTESand synthesis of proteins necessary to sup-
port spermatogenesis (production of SPERM). The
actions of FSH closely intertwine with those of
another pituitary hormone, LUTEINIZING HORMONE
(LH). Pituitary tumors can interfere with FSH syn-
thesis, causing the pituitary gland to produce
inadequate or excessive amounts. Extended use of
ANABOLIC STEROIDS AND STEROID PRECURSORS sup-
presses both GnRH and FSH (as well as LH),
resulting in symptoms of HYPOGONADISMthat are
most pronounced in men though can occur in
women as well. HORMONE THERAPYas treatment for
PROSTATE CANCERhas the same effect.
For further discussion of FSH within the context
of the endocrine system’s structure and function
please see the overview section “The Endocrine
System.”
See also ANDROGENS; ANTIDIURETIC HORMONE
(ADH); CRYPTORCHIDISM; ESTROGENS; FERTILITY; GROWTH
HORMONE(GH); KLINEFELTER’S SYNDROME; INFERTILITY;
OXYTOCIN; PROLACTIN; THYROID-STIMULATING HORMONE
(TSH); TURNER’S SYNDROME.follicle-stimulating hormone (FSH) 127