Hypopituitarism

Introduction Anterior pituitary hypofunction is a syndrome caused by insufficient secretion of hormones in the pituitary gland. The disease can be divided into partial and complete categories, the former involved only one to two hormones; the latter is the synthesis and secretion of all anterior pituitary hormones. The clinical manifestations mainly depend on the type and extent of anterior pituitary hormone deficiency; in addition, the age of onset also affects clinical manifestations.

Cause

Any damage that causes damage to the anterior pituitary or hypothalamus can cause anterior pituitary dysfunction. Postpartum pituitary necrosis (Sheehan syndrome) is the most common cause of this disease. The pituitary gland hyperplasia in the late pregnancy, when the birth or delivery, hemorrhage, causing hypotension, paralysis of the pituitary gland small artery, ischemic necrosis of the anterior pituitary. Generally, when glandular necrosis is >70%, clinical symptoms appear.

Another common cause is pituitary and pituitary tumors, especially chromoblastoma and craniopharyngioma. The iatrogenic anterior pituitary dysfunction is also common, mostly for surgical or radiotherapy damage to the pituitary and hypothalamus. Caused. Isolated individual pituitary hormone deficiency is often due to defects in the hypothalamus, resulting in a lack of secretion of released hormone, with gonadotropin (Gn) or growth hormone (GH) being the most common.

an examination

First, the surrounding gland function

(a) Adrenal function

The 124-hour urine 17-ketosteroid (17-KS), 17-hydroxysteroid (17-OHCS) and urinary free cortisol were lower than normal.

2ACTH stimulation test: ACTH25 dissolved in 5% grape glucose saline 500ml, intravenously, maintained for 8 hours, the patient showed a delayed response, that is, continuous intravenous infusion for 2 to 3 days, urine 17-KS and 17-OHCS gradually increased .

(two) thyroid function

1 Serum T3, T4 and thyroid 131I rates are lower than political parties.

2TSH Excitatory Test TSH 10 intramuscular injection once a day for 3 days. The patient's thyroid 131I glandular rate and serum T3, T4 may increase, but not as significant as normal, showing a delayed response.

(three) gonadal function

Male serum testosterone, urine 17-KS; female serum estradiol and urinary estrogen (estrone, estradiol, estriol) levels are low. A vaginal cytology smear test showed significant decrease in estrogen activity.

Second, the function of the anterior pituitary

(1) Serum TSH, LH, FSH, ACTH and GH may be lower than normal values.

(two) ACTH secretion test

1 metyrapone test: metyrapone is an 11-beta hydroxylase inhibitor, which can block the synthesis and secretion of cortisol, and feedback stimulates the secretion of ACTH in the anterior pituitary. Methionone 750mg, once every 4 hours, when the anterior pituitary function decreased, plasma ACTH did not increase.

2 insulin hypoglycemia stimulation test, insulin-induced hypoglycemia can stimulate the secretion of ACTH, GH and PRL in the anterior pituitary. Intravenous insulin 0.1u/kg, 30 minutes later, blood was taken to check ACTH. In normal people, ACTH should be >200 pmol/L, with an average of 300 pmol/L; ACTH in this case is low response or lack. This test has certain risks and is generally used with caution.

(3) Growth hormone (GH) secretion test

1 Insulin hypoglycemia stimulation test: The peak of normal reaction occurs 30 to 60 minutes after intravenous insulin injection, about 35 ± 20 g / L (35 ± 20 ng / ml); the reaction is reduced or no reaction in pituitary lesions.

2 levodopa excitatory test: oral levodopa 0.5g, 60-120 minutes after taking the drug, blood GH should be >7g / L (7ng / ml).

3 arginine stimulation test: 5% arginine 500ml intravenously. The normal GH peak is seen at 60 minutes after instillation, up to 3 times the baseline value; the disease is low or absent. 4 glucagon test glucagon 1mg, intramuscular injection. In normal people, the peak of 2 to 3 hours, >7g / L (7ng / ml), the disease has no obvious response.

(4) Prolactin (PRL) secretion test

1 thyroid stimulating hormone releasing hormone (TRH) test: 15 minutes after intravenous injection of TRH 500g, blood PRL peak, males can increase 3 to 5 times, women can increase 6 to 20 times. When the function of the anterior pituitary is low, its basal value is low and it cannot rise after excitement.

2 Detergent test Oral desperin 10 mg, the results were judged the same as the TRH test.

3 insulin hypoglycemia excitatory test: normal blood PRL reached a peak after intravenous injection of insulin for 1 hour, the highest can be 1.6 ~ 2.0nmol / L (40 ~ 50ng / ml), women are higher; the basic value of this disease is low, and the response is poor.

(5) Gonadotropin (Gn) secretion test

After 15 to 30 minutes of intravenous injection of luteinizing hormone releasing hormone (LHRH), the peak values of LH and FSH were more than three times that of women, and that of men was about twice. No response or low response suggested hypofunction of the anterior pituitary; peak appeared at 60-90 minutes for delayed response, suggesting hypothalamic lesions.

(6) Thyroid stimulating hormone (TSH) secretion test

Thirty minutes after intravenous injection of TRH500ng, the peak value of blood TSH was about 10 to 30 mu/L; there was no response in pituitary lesions.

According to the history, symptoms, signs and hormones of the pituitary gland and target gland, and the appropriate functional test, the diagnosis of the disease can be determined. The disease needs to be differentiated from diseases such as primary gonad, thyroid, adrenal insufficiency, anorexia nervosa and malnutrition. Diagnosis of the disease should be sought to find out the cause.

Differential diagnosis

Due to the lack of pituitary hormones, the symptoms and signs of this disease are also different.

1. Lack of gonadotropin (Gn or LH and FSH): Prepubertal onset is delayed in puberty, and post-pubertal onset is characterized by secondary hypogonadism. Patients with delayed puberty tend to be taller. Finger distance> height, genital not developed, testicles small and soft, long diameter amenorrhea. After puberty, the patient's pubic hair is shed, and the skin appears fine wrinkles; loss of libido, testicular atrophy, less sperm or no sperm; menopause, impotence and infertility.

Second, the lack of growth hormone (GH): in children and adolescence often cause bone growth retardation, short stature. There is no obvious feature in adults, but the patient's skin can be fine, the internal organs become smaller, and occasionally there can be fasting hypoglycemia.

Third, prolactin (PRL) deficiency: postpartum no milk, breast atrophy, often the first symptom of postpartum pituitary necrosis.

Fourth, the lack of thyroid hormone (TSH): can lead to hypothyroidism without glandular enlargement. Patients may have burnout, cold, dry skin, delayed Achilles tendon reflexes, but mucinous edema may not be obvious. If it occurs in childhood, growth retardation and delayed closure of the callus. The secretion of GH may be inhibited by the lack of TSH.

5. Adrenocorticotropic hormone (ACTH) deficiency: ACTH deficiency is often partial, usually after pituitary resection or pituitary radiotherapy. Insidious onset, such as weakness, nausea, vomiting, positional hypotension, hypoglycemia, weakness and coma. The areola is light, the skin is pale, and it is not dark for a long time. The secretion of mineralocorticoid is more controlled by the renin-angiotensin system, so when the pituitary cortical function is low, electrolyte imbalance is rarely caused.

Pituitary crisis: due to hypoplasia of anterior pituitary dysfunction for various stress factors, infection, diarrhea, vomiting, dehydration, hunger, trauma, surgery, anesthesia, cold and sleep, sedatives, etc. The original symptoms are aggravated and the crisis appears. The clinical manifestations of pituitary crisis are as follows.

(A) hypoglycemia coma: the most common. Often occurs on an empty stomach, palpitations, sweating, dizziness, disturbance of consciousness, sometimes mental disorders and convulsions or epileptic seizures, and finally coma.

(2) Infectious coma: low resistance, prone to infection, high fever; and unconsciousness and coma.

(3) Low body temperature coma: more common in the cold winter and when the patient is not warm.

(D) toxic coma in water: due to lack of corticosteroids, the ability to regulate water metabolism is reduced, when excessive infusion and drinking water, prone to toxic coma in water. Water poisoning is nausea, vomiting, collapse, insanity, convulsions and coma.

(5) coma after pituitary resection: postoperative unconsciousness, drowsiness, coma, lasting for several days to several weeks, pulse rate and low, body temperature can be low or high, normal blood sodium, blood sugar or partial low.

(6) Pituitary apoplexy: due to acute bleeding in pituitary tumors. Rapid onset, headache, dizziness, vomiting, decreased vision, blindness, even shock, coma.

(7) Sedation and anesthesia-induced coma: The patient is very sensitive to sedatives and anesthetics, and sometimes the usual dose can cause drowsiness or coma. And the duration is extended.

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