29 Endocrine Disorders Flashcards
- Review general physiological functions and regulation of the endocrine system
- Discuss the clinical manifestation and pathogenesis of thyroid and cortisol disorders
- Identify the diagnostic tests that aid in the work-up of patients with these disorders and treatment approaches
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Endocrine disorders:
Tertiary disorders: abnormality in stimulation from the ?
Secondary Disorders: Abnormality in stimulation from the ?
Primary Disorders: Abnormality in ?
Ectopic disorders: Abnormalioty in ?
Endocrine disorders:
Tertiary disorders: abnormality in stimulation from the hypothalamus (RARE)
Secondary Disorders: Abnormality in stimulation from the pituitary
Primary Disorders: Abnormality in Downstream endocrine gland
Ectopic disorders: Abnormalioty in site outside of the H-P axis
Cause of disorder
What is the dif between Hyperfunction and Hypofunction
Hyperfunction = Overproduction
Hypofunction = Underproduction
Thyroid hormone biochemistry and function
- Majority of thyroid hormones secreted is ?
- which is converted to ? in peripheral tissue and is many fold biologically active than ?
- ? is measured in work up of most thyroid disorders but ? can also be tested
- Thyroid hormones are highly ?, but a small fraction remains ?, which is the biologically active form → ? or ?
- Functions:
- Controls of basal ? rate
- Increases sensitivity of ? receptors to ?
- Regulates ?, ? and ? metabolism
- Role in ?, ? development, and ?
- Majority of thyroid hormones secreted is T4
- which is converted to T3 in peripheral tissue and is many fold biologically active than T4
- T4 is measured in work up of most thyroid disorders but T3 can also be tested
- Thyroid hormones are highly protein bound, but a small fraction remains unbound, which is the biologically active form → free T4 (FT4) or free T3 (FT3)
- Functions:
- Controls of basal metabolic rate
- Increases sensitivity of beta-adrenergic receptors to catecholamines
- Regulates protein, fat and carbohydrate metabolism
- Role in growth, brain development, and reproduction
Hypothyroidism:
Primary: (dysfunction at the ?)
- ? - autoimmune destruction
- ? - failure to develop
- Deficient synthesis due to ? deficiency
Secondary: (dysfunction at the ? (central))
- Inadequate secretion of ?
Tertiary: (dysfunction at ? (rare))
- Inadequate secretion of ?
Hypothyroidism = Deficient thyroid hormone production
Primary: (dysfunction at the thyroid gland)
- Hashimotos - autoimmune destruction
- Congenital - failure to develop
- Deficient synthesis due to iodine deficiency
Secondary: (dysfunction at the pituitary (central))
- Inadequate secretion of TSH
Tertiary: (dysfunction at hypothalamus (rare))
- Inadequate secretion of TRH
Hyperthyroidism = ?
Primary: (dysfunction at the ?)
- Graves disease - autoimmune activation of ? receptor
- Toxic ? goiter
- Exogenous ? hormone
- ? (non-cancerous tumor)
Secondary: (dysfunction at the ? (central))
- ?
Tertiary: (dysfunction at ? (rare))
- ?
Hyperthyroidism = excess thyroid hormone production
Primary: (dysfunction at the thyroid gland)
- Graves disease - autoimmune activation of TSH receptor
- Toxic multinodular goiter
- Exogenous thyroid hormone
- Adenoma
Secondary: (dysfunction at the pituitary (central))
- Pituitary Adenoma
Tertiary: (dysfunction at hypothalamus (rare))
- N/A
An adenoma is a benign tumor of epithelial tissue with glandular origin, glandular characteristics, or both (non-cancerous tumor)
What does the image suggest?
Low Free T4
High TSH
High TRH
Suggests abnormality at Thyroid gland (primary) resulting in low thyroid hormone production = Hypothyroidism
What disorder does the image suggest?
High Free T4
Low TSH (from pit)
Low TRH - from hypothalamus
Primary Hyperthyroidism
Diagnostic tests and tx for hypothyroidism
Test: 4
1. Plasma TSH (TRH not measured) = ?
2. Plasma FT4 = ?
3. Auto-antibodies, anti-TSH-Receptor antibodies (TRABS) and thyroid peroxidase (TPO) = ?
4. Investigative: ?
Treatment:
Hypothyroidism
Test:
1. Plasma TSH (TRH not measured) = HIGH
2. Plasma FT4 = LOW
3. Auto-antibodies, anti-TSH-Receptor antibodies (TRABS) and thyroid peroxidase (TPO) = POS
4. Ultrasound
Treatment:
Thyroid hormone replacement - L-Thyroxine
Diagnostic tests and treatment for hyperthyroidism
Hyperthyroidism
Test: 4
1. Plasma TSH (TRH not measured) = ?
2. Plasma FT4 = ?
3. Auto-antibodies, anti-TSH-Receptor antibodies (TRABS) and thyroid peroxidase (TPO) = ?
4. Investigative: ?
5. Radioactive ? uptake
Treatment:
Hyperthyroidism
Test:
1. Plasma TSH (TRH not measured) = LOW
2. Plasma FT4 = HIGH
3. Auto-antibodies, anti-TSH-Receptor antibodies (TRABS) and thyroid peroxidase (TPO) = POS
4. Investigative: Ultrasound
5. Radioactive iodine uptake
Treatment:
1. Anti-thyroid drugs: Propylthiouracil, methimazole
2. B-blocker
3. Radioiodine ablation
4. Surgery
Hypothyroidism
Test:
1. Plasma TSH (TRH not measured) = HIGH
2. Plasma FT4 = LOW
3. Auto-antibodies, anti-TSH-Receptor antibodies (TRABS) and thyroid peroxidase (TPO) = POS
4. Ultrasound
Treatment:
Thyroid hormone replacement - L-Thyroxine
Disorders of Cortisol Production
Hypercorticolism = ? syndrome
Primary Disorder = disfunction at ?
- ?
- ?
Secondary Disorder = dysfunction at ?
- ? disease - ?-secreting adenoma (most common)
Tertiary Disorder = dysfunction at ?
- ?-secreting tumors (rare)
Ectopic - Dysfunction where??
- ectopically produced ? such as in SCLC
Idiopathic:
- Pseudo-? from:
- ?
- ?
- high dose ? therapy
Hypercorticolism = Cushing’s syndrome
Primary Disorder = disfunction at adrenal gland
- Adrenal gland tumors
- hyperplasia
Secondary Disorder = dysfunction at pituitary
- Cushing disease - ACTH-secreting adenoma (most common)
Tertiary Disorder = dysfunction at Hypothalamus
- CRH-secreting tumors (rare)
Ectopic - Dysfunction outside the HPA axis??
- ectopically produced ACTH such as in SCLC (Small cell lung cancer)
Idiopathic:
- Pseudo-Cushings from:
- alcohol
- oral contraceptives (estrogen)
- high dose corticosteroid therapy
Hypocorticolism
Primary Disorder = disfunction at ?
- ? disease - Autoimmune destruction
- ? - genetic mutation that blocks cortisol production
Secondary Disorder = dysfunction at ?
- ? - suppresses ACTH production
- ? - blood loss and hypovolemic shock during or after childbirth
Tertiary Disorder = dysfunction at ?
- Sudden withdrawal of long-term ? use
- Brain cancer
Ectopic - Dysfunction where?
- ?
Idiopathic:
- ?
Hypocorticolism
Primary Disorder = disfunction at adrenal gland
- Addison disease - Autoimmune destruction
- Congenital Adrenal hyperplasia - genetic mutation that blocks cortisol production
Secondary Disorder = dysfunction at pituitary
- Adenoma - suppresses ACTH production
- Sheehan’s syndrome - blood loss and hypovolemic shock during or after childbirth
Tertiary Disorder = dysfunction at Hypothalamus
- Sudden withdrawal of long-term steroid use
- Brain cancer
Ectopic - Dysfunction outside the HPA axis??
- NA
Idiopathic:
- NA
What is the first step of screening of raised cortisol levels?
What does it mean if cortisol is elevated at night?
R/o causes of pseudo-cushings disease
1. Urinary cortisol (24hr collection)
2. Late-night salivary cortisol
3. Low dose overnight dexamethasone (DEXA)* *suppression test
Elevated cortisol at night (normally low at night) demonstrates loss of circadian rhythm and suggests hypercortisolism
- DEXA is a drug that acts like cortisol and under normal conditions, lowers the amount of ACTH released by the pituitary = lowered cortisol
- DEXA is given at 11pm then the next day 9am blood is drawn and cortisol measured
What is a DEXA suppression test and what does it measure?
- DEXA is a drug that acts like ? and under normal conditions, lowers the amount of ? released by the pituitary = lowers ?
- DEXA is given at 11pm then the next day 9am blood is drawn and ? measured
- Failure to suppress cortisol demonstrates loss of ? and suggests ?
Dexamethasone (DEXA) suppression test
- DEXA is a drug that acts like cortisol and under normal conditions, lowers the amount of ACTH released by the pituitary = lowers cortisol
- DEXA is given at 11pm then the next day 9am blood is drawn and cortisol measured
- Failure to suppress cortisol demonstrates loss of feedback inhibition and suggests pathologic hypercortisolism
Diagnosis and localization of Cushing’s
Measurement of ? helps localize tumour
Measurement of ACTH helps localize tumour
Cushings
What would the ACTH level be for the following tumor locations
