24 Questions
What is the primary function of cortisol in the body?
To provide substrate for glucose synthesis through catabolism of lipids and proteins
What is the normal range of cortisol in plasma?
5-25 µg/dl
What is the primary controller of cortisol secretion?
Pituitary gland
What is the term used to describe excessive ACTH secretion by a pituitary tumor?
Cushing's disease
What are the common symptoms of Cushing's syndrome?
Weight gain in the face, bone, and back of the neck, skin changes, and excess hair growth
What is the primary cause of Addison's disease?
Autoimmune disorder
What is the normal circadian rhythm of cortisol secretion?
Highest level between 7:00-9:00 am and lowest level between 4:00-11:00 pm
What is the purpose of the Dexamethasone suppression test?
To diagnose Cushing's syndrome
What is the function of Cortisol in the body?
To regulate nearly every type of organ and tissue within the body
Which layer of the adrenal cortex produces Cortisol?
Zona reticular and zona fasciculata
What is the function of Aldosterone in the kidney?
To increase absorption of Na in the distal tubules and facilitate secretion of K and H
What is the normal range of 24-hour urinary Aldosterone secretion?
2-26 µg/24hrs
What is the half-life period of Aldosterone?
20-30 minutes
What is the main regulator of Aldosterone secretion?
Renin-angiotensin system
What is the condition in which the adrenal gland releases too much of the hormone Aldosterone?
Conn's Syndrome
How is Aldosterone carried in plasma?
Bound to albumin and corticosteroid binding globulin (CBG)
What is the primary function of cortisol in the body?
To stimulate the output of glucose by the liver
What percentage of cortisol in plasma is bound to corticosteroid binding globulin (CBG)?
90%
What is the ratio of cortisol to corticosterol in the body?
90:10
What is the effect of cortisol on plasma glucose levels?
It elevates plasma glucose levels
What is the role of cortisol in the body?
It stimulates the output of glucose by the liver
What is the effect of cortisol deficiency on glucose levels?
It decreases glucose levels
What is the fate of cortisol in the plasma?
90% is bound to corticosteroid binding globulin (CBG)
What is the role of glucocorticoids in the body?
They stimulate the output of glucose by the liver
Study Notes
Adrenal Cortex Function and Disorder
Cortisol
- Cortisol is catabolized to provide substrates for glucose synthesis
- Cortisol secretion is controlled by ACTH from the pituitary and CRH from the hypothalamus
- Plasma cortisol levels range from 5-25µg/dl, with 20-100µg/24hrs urinary excretion
- Cortisol is metabolized mainly in the liver and secreted in the urine
Cushing's Syndrome
- Caused by excess cortisol production, often due to a pituitary tumor, adrenal tumor, or tumors elsewhere in the body
- Symptoms include weight gain, skin changes, easy bruising, excess hair growth, generalized weakness, and high blood pressure
- Cushing's disease refers specifically to excessive ACTH secretion by a pituitary tumor, which is relatively rare
Addison's Disease
- Caused by the failure to produce adequate cortisol levels, often due to autoimmune disorders, certain medications, sepsis, or bleeding into both adrenal glands
- Symptoms include weight loss, fatigue, low blood pressure, and electrolyte imbalances
Circadian Rhythm of Cortisol Secretion
- Cortisol levels peak between 7-9 am and are lowest between 4-11 pm
- Dexamethasone suppression test is used to diagnose suspected Cushing's syndrome
Adrenal Histology
- The adrenal gland is situated in the upper part of each kidney
- The adrenal cortex is formed of three layers: zona glomerulosa, zona reticular, and zona fasciculata
- Zona reticular and zona fasciculata produce cortisol, which regulates gluconeogenesis and has anti-inflammatory effects
- Zona glomerulosa produces aldosterone, which helps maintain water and salt balance in the body
Aldosterone
- Aldosterone is synthesized in the adrenal cortex, carries in plasma bound to albumin and corticosteroid binding globulin (CBG), and is metabolized in the liver
- Normal aldosterone secretion ranges from 2-26µg/24hrs
- Half-life of aldosterone is 20-30 minutes
Hyperaldosteronism (Conn's Syndrome)
- Primary hyperaldosteronism is a rare condition caused by a non-cancerous tumor of the adrenal gland (adenoma), adrenal hyperplasia, or glucocorticoid receptor defects
- Secondary hyperaldosteronism is often related to high blood pressure, cirrhosis of the liver, heart failure, and nephrotic syndrome
- Symptoms include fatigue, headache, high blood pressure, paralysis, muscle weakness, and numbness
- Laboratory findings include hypernatremia, hypokalemia, and metabolic alkalosis
Hypoaldosteronism
- Often occurs in Addison's disease due to destruction of the adrenal cortex by disease
- Can also occur isolated due to adrenal gland destruction, G-layer enzyme deficiencies, or mild renal insufficiency
- Symptoms include high serum potassium, low urinary potassium excretion (urine K < urine Na), and mild metabolic acidosis
This quiz covers the functions and regulation of cortisol, including its role in glucose synthesis, metabolism, and excretion, as well as disorders of cortisol secretion such as Cushing's syndrome.
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