Endocrinology

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By The Name Of The God
Internal medicine
Endocrinology

DISEASES OF THE PITUITARY GLAND
The pituitary is divided into 2 lobes—
1 The Adenohypophysis or (anterior
the pituitary

lobe), which constitutes 80% of

2 The NEUROhypophysis or (posterior lobe), which is the storage
site for hormones produced by the neurosecretory neurons (supraoptic
and paraventricular nuclei) within the hypothalamus. The 2 hormones
stored in the are ADH (antidiuretic hormone or vasopressin)

and oxytocin
 (focus ) The hormones Of posterior lobe (ADH and oxytocin)
produced by hypothalamus (by the neurosecretory neurons
(supraoptic and paraventricular nuclei) )
The hypothalamus regulates the release of hormones from the anterior pituitary
by different hypothalamic releasing and inhibiting hormones (hypothalamic–
pituitary axis)
- Each pituitary hormone stimulates release of the active hormone from the final
target gland. The active hormones then inhibit release of releasing factors and stimulatory hormones from the hypothalamus and pituitary gland, respectively. This is
feedback inhibition (e.x ACTH go to adrenal stimulates to produced cortisol and
cortisol go back to hypothalamus and stops releasing the ACTH it’s called

((Feedback ))

We use this physiology to screen and diagnose these
diseases

Hormones OF THE ANTERIOR PITUITARY

Symbol

Hormone

(s)

Adrenocorticotr
opic hormone

Structure

Target

Effect

Secretion
ACTH

Polypeptide

Adrenal gland

of glucocorticoid, mineralocorticoidand
androgens

Beta-endorphin

Polypeptide

Opioid receptor

Inhibit perception of pain

TSH

Glycoprotein

Thyroid gland

Secretion of thyroid hormones

FSH

Glycoprotein

Gonads

Growth of reproductive system

Glycoprotein

Gonads

Sex hormone production

Thyroidstimulating
hormone

Folliclestimulating
hormone

Luteinizing

LH,

hormone

ICSH

Growth

GH,

hormone

STH

Prolactin

Leptin

PRL

-

Promotes
Polypeptide

Liver, adipose tissue

growth; lipid and carbohydratemetabolis
m

Polypeptide

Polypeptide

Ovaries, mammary
glands

Corticotrophic andThyr
otrophic cells

Secretion
of estrogens/progesterone; milkproducti
on

TSH and ACTH secretion

Hormones OF THE Posterior PITUITARY (neurohypophysis)

Symbol(

Hormone

Main targets

s)

Oxytocin

OT

Uterus,mammary
glands

Effect

Uterine
contractions; lactati
on

Source

supraoptic andparaventricu
lar nuclei

Stimulates water
retention; raises

ADH
(Vasopressin)

VP, AVP,

Kidneys orArteriol

blood pressure by

supraoptic andparaventricu

ADH

es

contracting

lar nuclei

arterioles, induces
male aggression

These hormones produced in supraoptic and paraventricular nuclei and storage
an d secreted from Posterior Pituitary (neurohypophysis)

DISEASES OF THE ANTERIOR PITUITARY



Microadenomas are defined as tumors <1 cm in diameter.
Macroadenomas are tumors >1 cm in diameter.

 Microadenomas are more common than macroadenomas


Larger tumors can occasionally compress the optic chiasm and can cause visual deficits.

Pituitary Adenomas by Function

Hyperprolactinemia

Prolactin

50–60%

Growth hormone (GH)

15–20%

ACTH

10–15%

Gonadotroph

10–15%

Definition. Excess prolactin secretion is a common clinical problem in women and causes the
syndrome of galactorrhea-amenorrhea. The amenorrhea appears to be caused by inhibition of
hypothalamic release of gonadotropin-releasing hormone (GnRH) with a decrease in
luteinizing hormone (LH) and Follicle-stimulating hormone (FSH) secretion. Prolactin inhibits
the LH surge that causes ovulation. The LH/FSH-producing cells are not destroyed, just
suppressed. Although hyperprolactinemia is also seen in men, gynecomastia and especially
galactorrhea are very rare.
The most common presenting symptom in men is erectile dysfunction and decreased
libido.
Prolactinomas : Autonomous production of prolactin occurs with pituitary adenomas
Prolactinomas (Hyperprolactinemia) the most common functioning pituitary adenomas,
accounting for 60% of all pituitary tumors

They are usually microadenomas when they occur in women and macroadenomas in men,
usually presenting with visual field deficits. (in women we will detected the adenoma early due to
the to many and clear symptoms )
-

Macroadenomas can obstruct the pituitary stalk, increasing prolactin release by blocking
dopamine transport from hypo-thalamus (stalk effect). Other examples are tumors, such as
craniopharyngioma, meningioma, and dysgerminoma; empty sella; and trauma .

Etiology :
- natural physiologic states :

1- pregnancy
2- early nursing
3- Hypoglycemia
4- Seizure
5- Exercise
6- Stress
7- Sleep
8- Cirrhosis
9- nipple stimulation
10- Chronic renal failure (due to PRL clearance).
11- Acromegaly

-

Hyperprolactinemia can also occur with decreased inhibitory action of dopamine

12345-

The use of drugs that block dopamine synthesis (phenothiazines, metoclopramide )
dopamine-depleting agents (-methyldopa, reserpine)
Tricyclic antidepressants
Narcotics , cocaine
SSRIs

Other
1- Primary hypothyroidism (resulting in an increase in thyrotropin-releasing hormone [TRH]) and
subsequently an increase in prolactin release.
Always check TSH in patients with elevated prolactin

Clinical.
women
galactorrhea, menstrual abnormalities
amenorrhea/oligomenorrhea, osteopenia and
osteoporosis in long-standing cases, infertility,
and gynecomastia

men
dysfunction, decreased libido (most
common ) hypogonadism , gynecomastia , and
infertility
erectile

In both may be
2-

1- Hemianopia (more in men due to the size of the tumor
Because of hypoestrogenism and hypoandrogenism, hyperprolactinemia can lead to osteoporosis

3-

*# Women are detected earlier because of menstrual symptoms. Hence, microadenomas are more
common in women
Diagnosis. At first Time e xc l ude states
-

Pregnancy by hCG

-

Hypothyroidism By TSH

-

Lactation

-

Medications

Before starting the work-up of hyperprolactinemia. Prolactinomas may secrete growth hormone (GH).

The normal values for prolactin are:
Males: 2 - 18 ng/mL.
Nonpregnant females: 2 - 29 ng/mL.
Pregnant women: 10 - 209 ng/mL.

o
o
o

Dx :1-

Prolactin levels >100 ng/mL suggest probable pituitary adenoma
in non-pregnant women
Usually with
-

-

Prolactin levels 100 ng/ml = tumor size 1 cm
Prolactin levels 200 ng/ml = tumor size 2 cm. etc.

** MRI PRL level >100 to 200 mg/L (normal <20 mg/L) in a nonpregnant woman indicates a need for an MRI
of the pituitary.

Management:
For Prolactinomas, initially treat with cabergoline or bromocriptine (a dopamine agonist), which
reduce prolactin levels in almost all hyperprolactinemic patients. Dopamine normally inhibits
prolactin release. Surgery is reserved only for adenomas not responsive to cabergoline or
bromocriptine, or if the tumor is associated with significant compressive neurologic effects.

Surgery is more effective for microadenomas than macroadenomas.
About 90% of patients treated with cabergoline have a drop in prolactin to <10% of pretreatment levels.
Radiation therapy is used
prolactin levels

if drug therapy and surgery are ineffective in reducing tumor size and

Notes
1234-

The most common presenting symptom in men is erectile dysfunction and decreased libido.
The Most common adenoma of the Pituitary is Hyperprolactinemia 60 %
The most common presenting symptom in Women are galactorrhea (58%), oligomenorrhea (58%)
The Treatment Of choice of Hyperprolactinemia is Medical treatment by cabergoline(used mostly )
or bromocriptine .

5- Cabergoline is used more often than bromocriptine because of a better side-effect profile. It should
be considered the preferred medical treatment for galactorrhea.

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