Sheehan Syndrome affects the pituitary gland, located at the base of the brain. It is a serious complication following childbirth when a woman experiences severe blood loss or extremely low blood pressure during or immediately after delivery. This event damages the pituitary tissue, leading to a deficiency in the hormones the gland produces. Also known as postpartum hypopituitarism, the condition requires medical attention because the pituitary gland regulates many endocrine functions.
How Sheehan Syndrome Develops
The mechanism behind Sheehan Syndrome is ischemic necrosis, which is tissue death caused by a lack of blood flow and oxygen. The pituitary gland is particularly vulnerable during pregnancy because it increases significantly in size, sometimes doubling, due to the multiplication of prolactin-producing cells. This enlargement greatly increases the gland’s metabolic demands and its need for a steady blood supply.
When a woman experiences postpartum hemorrhage, the resulting drop in blood pressure and overall blood volume starves the enlarged pituitary gland of necessary oxygen. The anterior portion of the gland, supplied by a low-pressure portal venous system, is most commonly affected by this ischemic injury. The lack of oxygen causes the anterior pituitary tissue to die, leading to a long-term inability to produce adequate levels of its various hormones.
Clinical Signs and Long-Term Effects
The signs of Sheehan Syndrome can appear immediately after delivery in severe cases, but they often develop gradually over months or even years if the damage is less extensive. The specific manifestations depend on which pituitary hormones are deficient and the degree of that deficiency. The first sign is frequently a failure to lactate because the gland cannot secrete enough prolactin.
A lack of gonadotropins, specifically Luteinizing Hormone (LH) and Follicle-Stimulating Hormone (FSH), results in reproductive system changes. These deficiencies typically cause the absence of menstrual periods (amenorrhea) or irregular periods (oligomenorrhea) following delivery. Patients may also experience a decreased sex drive, vaginal dryness, and the loss of underarm and pubic hair.
Deficiency in Thyroid-Stimulating Hormone (TSH) leads to secondary hypothyroidism, which can manifest as fatigue, cold intolerance, and dry skin. Patients may also notice weight gain and slowed mental function due to the reduced rate of metabolism. A lack of Adrenocorticotropic Hormone (ACTH) is concerning, as it controls the adrenal glands’ release of cortisol.
ACTH deficiency causes secondary adrenal insufficiency, leading to symptoms like generalized weakness, low blood pressure, and hypoglycemia. In times of physical stress, such as illness or injury, this deficiency can lead to a life-threatening acute adrenal crisis. Additionally, a lack of Growth Hormone (GH), a common deficiency, contributes to low energy, body aches, and subtle skin changes.
Confirmation and Treatment Strategies
Diagnosis of Sheehan Syndrome begins with a detailed medical history, focusing on delivery complications and the appearance of symptoms like lactation failure or amenorrhea. Since the symptoms often resemble other conditions, laboratory testing is necessary to confirm the diagnosis. Blood tests measure the levels of various pituitary hormones, including ACTH, TSH, LH, and FSH.
A more definitive diagnostic tool is the pituitary hormone stimulation test, which assesses the gland’s functional reserve. This test involves stimulating the pituitary with an injected substance and then measuring the resulting hormone output. Imaging, such as Magnetic Resonance Imaging (MRI), may also be used to look for changes in the pituitary gland’s structure, such as an empty sella turcica, which indicates tissue loss.
The management of Sheehan Syndrome requires Hormone Replacement Therapy (HRT) to substitute the hormones the damaged pituitary gland can no longer produce. Glucocorticoid replacement, typically hydrocortisone or prednisone, is necessary to prevent adrenal crisis. Thyroid hormone replacement, usually levothyroxine, is initiated only after glucocorticoid therapy has begun to avoid precipitating an adrenal crisis.
If fertility is not desired, sex hormone replacement involves estrogen, often combined with progesterone if the uterus is still present, to regulate menstrual cycles and prevent premature menopause symptoms. Patients must have their hormone levels regularly monitored by a specialist, and dosages must be carefully adjusted based on blood tests and clinical symptoms. Patients receiving cortisol replacement must also be educated on “sick day rules,” which involve increasing their dose during periods of significant physical stress.