Endocrine system pathophysiology
Monday, 16 July 2018 11:05 AM
The endocrine system
The communication between cells, tissues and organs
The control mechanisms are required to ensure optimal functioning
It works in conjunction with the nervous system and is responsible for the regulation of a wide range of
functions, including:
Growth
Development
Reproduction
Homeostasis
Response to external stimuli and stress
Failures in these communication channels are common and may lead to many diseases of the endocrine system
Endocrine glands:
• Pituitary glands
• Adrenal glands
• Thyroid gland and parathyroid glands
• Pineal gland
• Testicles
• Ovaries Thyroid gland anatomy
• Pancreas
The thyroid gland
The thyroid hormones are essential for:
i) Normal brain development
ii) Growth
iii) Metabolism
Synthesis is dependent on:
i. Normal development of thyroid gland
ii. Adequate dietary intake of iodine
iii. Series of biochemical steps to organify iodine
FLG 332 Page 1
, Synthesis is dependent on:
i. Normal development of thyroid gland
ii. Adequate dietary intake of iodine
iii. Series of biochemical steps to organify iodine
Class note:
Explanation of class note:
Negative feedback loop
Hormone synthesis and secretion
Peripheral circulation
FLG 332 Page 2
, Peripheral circulation
Receptor binding and hormone action
Long loop
TH1- Trophic hormone 1
TH2 - Trophic hormone 2
EH - Endocrine hormone
Anterior pituitary "tropic"
a. TSH
b. ACTH
c. FSH All hormones are made in the hypothalamus and stored in the pituitary gland
d. LH
e. GH
f. PRL - prolactin
Posterior pituitary
a. Oxytocin
b. ADH
resistance = looks like a hyper situation but the end result looks like a hypo situation
Groups at increased risk of thyroid dysfunction :
1. General :
A. Positive family history
B. Previous postpartum thyroid dysfunction
C. Positive thyroid peroxidase antibody
D. Previous thyroid disease or surgery
E. Women over age 55
F. Origin from areas of endemic iodine deficiency
G. Very low birth weight premature infants
2. Therapy :
A. Pituitary surgery or irradiation
B. Head and neck irradiation
C. Radical laryngeal/pharyngeal surgery
D. Treatment of growth hormone deficiency
E. Cytotoxic therapy
F. Lithium
G. Amiodarone
H. Exposure to iodine excess, e.g contrast agents
I. Interferon α, interferon β
FLG 332 Page 3
, I. Interferon α, interferon β
J. Interleukin 2
K. Therapeutic monoclonal antibodies
L. Granulocyte colony stimulating factor
3. Associated diseases:
A. Diabetes mellitus
B. Any autoimmune disease
C. Other endocrine deficiencies
D. Down syndrome
E. Turner syndrome
F. Thalassaemia major
G. Pituitary or hypothalamic abnormality
H. Severe head injury
I. Recent Cushing's syndrome
NB - do not confuse between TSH and TRH they are different (TRH = Thyroid releasing hormone)
Thyroid function :
• Primary hypothyroidism - fT4 <10 pmol/l, fT3 <3.0 pmol/l, TSH > 5mU/L
□ Primary: fT4 <10 pmol/l, fT3 <3.0 pmol/l, TSH > 5mU/L, TRH high
□ Secondary: fT4 <10 pmol/l, fT3 <3.0 pmol/l, TSH and TRH high or low depending on origin
• Primary hyperthyroidism - fT4 >22 pmol/l, fT3 >9 pmol/l, TSH <0.5mU/L
□ Primary : fT4 >22 pmol/l, fT3 >9 pmol/l, TSH <0.5mU/L, TSH low
□ Secondary: fT4 >22 pmol/l, fT3 >9 pmol/l, TSH or TRH high or low depending on origin
These can be caused by autoimmune disorder, infection, cancer, other illnesses and receptor resistance
Iodine deficiency
- Causes:
○ Adverse effects on growth and development
○ Inadequate production of thyroid hormone
○ Preventable mental impairment
- Assessment methods include :
○ Urinary iodine concentrations
○ Goitre
○ New born thyroid stimulating hormone
○ Blood thyroglobin
- Consequences of iodine-deficiency
○ All ages - goitre, increased risk of hypothyroidism and the enhanced susceptibility of the thyroid gland to
nuclear radiation
○ Foetus - abortion, still birth and congenital anomalies
○ Neonate - endemic cretinism and increased infant mortality
○ Childhood - delayed milestones and physical development and mental functioning impaired
○ Adulthood - impaired mental functioning , subtle and widespread effects secondary to hypothyroidism -
decreased educability, apathy, reduced work productivity. Population becoming socially and economically
impaired
Deficiency of TH in infants cause cretinism:
FLG 332 Page 4
Monday, 16 July 2018 11:05 AM
The endocrine system
The communication between cells, tissues and organs
The control mechanisms are required to ensure optimal functioning
It works in conjunction with the nervous system and is responsible for the regulation of a wide range of
functions, including:
Growth
Development
Reproduction
Homeostasis
Response to external stimuli and stress
Failures in these communication channels are common and may lead to many diseases of the endocrine system
Endocrine glands:
• Pituitary glands
• Adrenal glands
• Thyroid gland and parathyroid glands
• Pineal gland
• Testicles
• Ovaries Thyroid gland anatomy
• Pancreas
The thyroid gland
The thyroid hormones are essential for:
i) Normal brain development
ii) Growth
iii) Metabolism
Synthesis is dependent on:
i. Normal development of thyroid gland
ii. Adequate dietary intake of iodine
iii. Series of biochemical steps to organify iodine
FLG 332 Page 1
, Synthesis is dependent on:
i. Normal development of thyroid gland
ii. Adequate dietary intake of iodine
iii. Series of biochemical steps to organify iodine
Class note:
Explanation of class note:
Negative feedback loop
Hormone synthesis and secretion
Peripheral circulation
FLG 332 Page 2
, Peripheral circulation
Receptor binding and hormone action
Long loop
TH1- Trophic hormone 1
TH2 - Trophic hormone 2
EH - Endocrine hormone
Anterior pituitary "tropic"
a. TSH
b. ACTH
c. FSH All hormones are made in the hypothalamus and stored in the pituitary gland
d. LH
e. GH
f. PRL - prolactin
Posterior pituitary
a. Oxytocin
b. ADH
resistance = looks like a hyper situation but the end result looks like a hypo situation
Groups at increased risk of thyroid dysfunction :
1. General :
A. Positive family history
B. Previous postpartum thyroid dysfunction
C. Positive thyroid peroxidase antibody
D. Previous thyroid disease or surgery
E. Women over age 55
F. Origin from areas of endemic iodine deficiency
G. Very low birth weight premature infants
2. Therapy :
A. Pituitary surgery or irradiation
B. Head and neck irradiation
C. Radical laryngeal/pharyngeal surgery
D. Treatment of growth hormone deficiency
E. Cytotoxic therapy
F. Lithium
G. Amiodarone
H. Exposure to iodine excess, e.g contrast agents
I. Interferon α, interferon β
FLG 332 Page 3
, I. Interferon α, interferon β
J. Interleukin 2
K. Therapeutic monoclonal antibodies
L. Granulocyte colony stimulating factor
3. Associated diseases:
A. Diabetes mellitus
B. Any autoimmune disease
C. Other endocrine deficiencies
D. Down syndrome
E. Turner syndrome
F. Thalassaemia major
G. Pituitary or hypothalamic abnormality
H. Severe head injury
I. Recent Cushing's syndrome
NB - do not confuse between TSH and TRH they are different (TRH = Thyroid releasing hormone)
Thyroid function :
• Primary hypothyroidism - fT4 <10 pmol/l, fT3 <3.0 pmol/l, TSH > 5mU/L
□ Primary: fT4 <10 pmol/l, fT3 <3.0 pmol/l, TSH > 5mU/L, TRH high
□ Secondary: fT4 <10 pmol/l, fT3 <3.0 pmol/l, TSH and TRH high or low depending on origin
• Primary hyperthyroidism - fT4 >22 pmol/l, fT3 >9 pmol/l, TSH <0.5mU/L
□ Primary : fT4 >22 pmol/l, fT3 >9 pmol/l, TSH <0.5mU/L, TSH low
□ Secondary: fT4 >22 pmol/l, fT3 >9 pmol/l, TSH or TRH high or low depending on origin
These can be caused by autoimmune disorder, infection, cancer, other illnesses and receptor resistance
Iodine deficiency
- Causes:
○ Adverse effects on growth and development
○ Inadequate production of thyroid hormone
○ Preventable mental impairment
- Assessment methods include :
○ Urinary iodine concentrations
○ Goitre
○ New born thyroid stimulating hormone
○ Blood thyroglobin
- Consequences of iodine-deficiency
○ All ages - goitre, increased risk of hypothyroidism and the enhanced susceptibility of the thyroid gland to
nuclear radiation
○ Foetus - abortion, still birth and congenital anomalies
○ Neonate - endemic cretinism and increased infant mortality
○ Childhood - delayed milestones and physical development and mental functioning impaired
○ Adulthood - impaired mental functioning , subtle and widespread effects secondary to hypothyroidism -
decreased educability, apathy, reduced work productivity. Population becoming socially and economically
impaired
Deficiency of TH in infants cause cretinism:
FLG 332 Page 4
