Download Clinical Manifestations

Chapter 7
The endocrine system
The endocrine system, along with the nervous
system, allows for communication between
distant sites in the body.
the endocrine system has three components :
1-endocrine glands that secrete chemical
messengers into the bloodstream;
2-the chemical messengers themselves, called
hormones;
3-and the target cells or organs that respond to
the hormones.
Conditions of Disease or Injury
Hypothyroidism
Result from malfunction of the thyroid gland, the
pituitary, or the hypothalamus.
-If it results from thyroid gland malfunction, low TH
(thyroxin hormone) levels are accompanied by high
TSH( thyroid stimulating hormone) and high TRH
(thyroid releasing hormone) because of the lack of
negative feedback on the pituitary and
hypothalamus by TH.
-If hypothyroidism results from pituitary malfunction,
low levels of TH are caused by low TSH. TRH from
the hypothalamus is high because there is no
negative feedback on its release by TSH or TH.
- Hypothyroidism caused by hypothalamic
malfunction results in low TH, low TSH, and low
TRH.
Causes of Hypothyroidism
• - Hashimoto's disease, also called autoimmune
thyroiditis, results from autoantibody destruction
of thyroid gland tissue.
• - Endemic goiter is hypothyroidism caused by a
dietary deficiency of iodide.
N.b., A goiter is an enlargement of the thyroid gland.
• - Thyroid carcinoma may cause hypothyroidism or
hyperthyroidism.
Clinical Manifestations
• - Sluggishness and slow thinking, and slow
movements.
• - Decreased heart rate.
• - Edema of the skin, especially under the eyes and
in the ankles(myxedema)
• - Intolerance to cold temperatures.
• - Decreased metabolic rate, decreased caloric
requirements, decreased appetite and nutrient
absorption across the gut.
• - Constipation
Diagnostic Tools
Measuring levels of TH (both T3 and T4), TSH, and
TRH will allow diagnosis of the condition and
localization of the problem .
Pediatric Consideration
• Infants born without a thyroid gland or with defects
in TH synthesis will develop congenital
hypothyroidism, a disease sometimes referred to as
cretinism. It is characterized by low TH, with high
TSH and TRF. TH is necessary for all cells ,including
cells of the central nervous system (CNS).
Development of the CNS occurs in utero and for
approximately 1 year after birth. Because an infant
with congenital hypothyroidism was exposed to
maternal TH in utero, it will be born neurologically
intact. If TH is not replaced, severe mental
retardation will result. With thyroxine replacement,
CNS damage can be avoided.
Hyperthyroidism
Hyperthyroidism is excessive levels of circulating TH.
-Increased TH caused by malfunction of the thyroid
gland is accompanied by decreased TSH and TRF, as
a result of the negative feedback on their release by
TH.
-Hyperthyroidism caused by malfunction of the
pituitary results in high TH and high TSH. TRF is low
because of negative feedback from TH and TSH.
-Hyperthyroidism caused by malfunction of the
hypothalamus shows high TH accompanied by
excess TSH and TRH.
Clinical Manifestations
• - Increased heart rate.
• - Increased muscle tone, tremors, irritability
• - Increased basal metabolic rate and heat
production, intolerance to heat, excess sweating.
• - Weight loss, increased hunger.
• - Exophthalmos (bulging of the eyes) may develop.
• - Increased number of bowel movements.
• - Goiter (usually).
Diagnostic tools
- Measuring levels of TH (both T3 and T4), TSH, and
TRH will allow diagnosis of the condition and
localization of the problem.
Adrenal Insufficiency
Adrenal insufficiency is a decrease in the
circulating level of the glucocorticoids.
The mineralocorticoid aldosterone may
also be reduced.
Adrenal insufficiency may be caused by
dysfunction of the adrenal gland, called
primary adrenal insufficiency, or by
dysfunction of the pituitary or
hypothalamus. Both of these latter
conditions cause secondary adrenal
insufficiency.
•Primary adrenal insufficiency is characterized by
low levels of glucocorticoids, especially cortisol,
accompanied by high ACTH( adreno corticotropic
hormone) and high CRH( cortzone releasing
hormone) because there is no negative feedback on
their release.
•If the cause of adrenal insufficiency is secondary to
a pituitary dysfunction, low glucocorticoids will be
accompanied by low ACTH and high CRH. In this
case, adrenal androgens will also be low. If there is
zero ACTH, aldosterone levels will be reduced.
•If adrenal insufficiency is caused by a hypothalamus
malfunction, the glucocorticoids, ACTH, and CRH will
be low.
Diseases of Adrenal Insufficiency
• Primary adrenal insufficiency, called Addison's disease,
occurs from destruction of the adrenal cortex. The
disease is usually autoimmune, and may results from
infections such as TB or tumors.
Addison's disease is characterized by low glucocorticoid
levels accompanied by high ACTH and high CRH. Total
loss of the adrenal gland results in the loss of adrenal
androgens and aldosterone as well. Aldosterone
deficiency leads to increased loss of sodium in the
urine, resulting in hyponatremia (decreased sodium in
the blood), dehydration, and hypotension (water
follows salt). Decreased potassium excretion in the
urine will lead to hyperkalemia (increased potassium
concentration in the blood).
Clinical Manifestations
• - Depression, because cortisol levels influence
mood and emotions.
• - Fatigue, related to hypoglycemia, and decreased
gluconeogenesis.
• - Anorexia, vomiting, diarrhea, and nausea.
• - Hyperpigmentation of the skin if ACTH levels are
high (primary adrenal insufficiency) as ACTH has
melanin-stimulating hormone like effects on the
skin.
• - Sparse body hair in women, if the adrenal cells
producing androgens are destroyed .
• - Inability to respond to stressful situations, perhaps
leading to severe hypotension.
Glucocorticoid Excess
Glucocorticoid excess refers to any condition in
which there are very high levels of circulating
glucocorticoids. The cause of glucocorticoid excess
may be at the level of the adrenal gland or at the
pituitary/hypothalamic level. If the cause is primary
adrenal gland hypersecretion, (usually an adrenal
tumor present). In this situation, low ACTH and low
CRH levels will be present as a result of negative
feedback.
Adrenal androgen levels will be low because ACTH
is low. Bronzing of the skin will not occur.
Diseases of Excess Glucocorticoids
• - Cushing's syndrome refers to any condition of
high glucocorticoids and includes glucocorticoid
excess caused by therapeutic administration of
corticosteroids.
• - Cushing's disease refers to high glucocorticoids
caused specifically by malfunction of the anterior
pituitary resulting in excess ACTH.
Clinical Manifestations
• - Altered fat metabolism leading to fat pads on the
back (buffalo hump), moon face, protruding
abdomen with thin extremities, and stretch marks
on breasts, thighs, and abdominal surface.
• - Muscle weakness from protein breakdown.
• - Hypertension as a result of increased
catecholamine responsiveness.
• - Weight gain resulting from strong appetite
stimulation.
• - Inhibition of immune and inflammatory reactions,
leading to poor wound healing.
• - Masculinization of women and children as a result
of adrenal androgen stimulation if ACTH levels are
high.
• - Bronzing of the skin if ACTH levels are high.
Growth Hormone Deficiency(Pituitary Dwarfism)
• Growth hormone deficiency is a decrease in
circulating levels of GH. Most cells of the body will
be affected. GH deficiency is usually clinically
recognized only in children. Usually is caused by a
pituitary adenoma .
• Clinical Manifestations
• - proportional short stature .
• - Delayed onset of puberty
Growth Hormone Excess
• Growth hormone excess is the increase in
circulating levels of GH usually caused by a GHsecreting tumor of the anterior pituitary.
Diseases of GH Excess
• - Gigantism, a disease of excess longitudinal growth of
the bones of the skeleton, is seen as a result of GH
excess before puberty.
• - Acromegaly, a disease of connective tissue
proliferation, is seen in adults with GH excess. Because
long bone growth has stopped in adults, GH excess
cannot cause growth of the skeleton. It is associated
with growth of the cartilage of the hands, feet, nose,
jaw, chin, and facial bones.
Clinical Manifestations
• - Tall stature with gigantism.
• - Thickening of the fingers, jaw, forehead, hands, and
feet with acromegaly.
Gonadotropin Deficiency
Gonadotropin deficiency is a decrease in circulating
levels of FSH and LH.
Clinical Manifestations
• - Amenorrhea (lack of menstrual periods), vaginal,
uterine, and breast atrophy in women.
• - Testicular atrophy and reduction in beard growth
in men.
Syndrome of Inappropriate Antidiuretic
Hormone (ADH)
(SIADH) is characterized by increased release of
ADH from the posterior pituitary
Clinical Manifestations
• - Water retention and weight gain.
• - Decreased urinary output.
• - Nausea and vomiting worsening with the
degree of water intoxication.
Diagnostic Tools
Blood tests measuring increased levels of ADH
with low plasma sodium concentration (
hyponatremia) .
Diabetes Insipidus
Diabetes insipidus is a disease of decreased ADH
production.
Clinical Manifestations
- Large volumes of dilute urine.
- Polydipsia (excessive thirst).
Diagnostic Tools
Blood tests measuring decreased levels of ADH with
hypernatremia will allow diagnosis of the condition.
Complications
Severe dehydration may occur if large volumes of
drinking water are unavailable.