Topic 5 Endocrine Conditions Flashcards
Endocrine functions
Homeostasis
Stress response
Growth and development
Sexual maturation
Endocrine regulation
Hormones are released in response to altered cellular environment; and to maintain a regulated level of certain substances or other hormones.
Regulated by three secretion patterns
- Diurnal patterns fluctuating around a 24hr cycle
- Pulsatile and cyclic patterns fluctuating around other cycles
- Patterns that depend on levels of substances circulating within blood stream
Negative feedback
Rising hormone level prevents hormone release. Prevent the systems from becoming overactive.
Syndrome of inappropriate antidiuretic hormone secretion
Hypersecretion of ADH interferes with renal water excretion. As a result, plasma sodium is diluted in larger quantities of water, leading to hypernatremia and hypo-osmolality.
Diabetes Insipidus
Hyposecretion of ADH
Neurogenic - caused by insufficient ADH release from posterior pituitary)
Nephrogenic - inadequate kidney response to hormone
Acute onset —> Polyuria and polydipsia —> dehydration without fluid replacement
Role of growth hormone
Responsible for development of muscles and bones and targets nearly every cell of the body
GH deficiency
Interferes with linear bone growth
Results in short stature or dwarfism
Tx: Somatotropin
GH excess
Results in increased linear bone growth
Gigantism, acromegaly
Tx: Somatostatin
Function of RAAS
Renin is released flowing through kidneys and diffuses throughout circulation -> plasma renin converts angiotensinogen to angiotensin 1 -> angiotension 1 converted to angiotensin 2 by ACE -> angiotensin 2 vasoconstrictive peptide causing rise in BP -> angiotensin 2 stimulates aldosterone secretion causing increased NA and H2O reabsorption increasing BP.
Action of ADH
Made in hypothalamus and released from the posterior pituitary gland. Exhibits vasoconstrictive properties. Main course of action is to stimulate reabsorption of water in the kidneys. ADH acts on the central nervous system to increase an individual’s appetite for salt and to stimulate the sensation of thirst.
Regulation of ADH
Osmoreceptors in the Hypothalamus sense the osmolality of the plasma. This stimulates the release or inhibition of ADH
What is Cushing’s syndrome
Hypercortisolism (excessive level of cortisol)
Excessive anterior pituitary secretion of adrenocorticotropic hormone, tumour on pituitary, adrenal ectopic ACTH secreting, long term use of glucocorticoids.
CM of Cushing’s syndrome
Weight gain Sodium and water retention Thinning of hair Acne Increased body hair Easy bruising Increased risk of infection with masked manifestations. Glucose intolerance Muscle wasting on extremities Breast atrophy Generalized oedema Hypertension Osteoporosis
Dx of Cushing’s syndrome
CT MRI 24 hr urine collection Plasma levels of ACTH Suppression/stimulation tests of HPA system
Tx of Cushing’s syndrome
Medication (block steroid synthesis)
Radiotherapy
Surgery (remove tumour)
What is hypothyroidism
Condition caused by malfunction of thyroid, insufficient iodine in the diet or insufficient secretion of TSH and TRH
CM of hypothyroidism
Low appetite Weight gain Fatigue Mental and physical sluggishness Somnolence Low cardiac output Bradycardia Constipation Hypoventilation Cold intolerance Dry skin Course hair Myxoedema (coma)
Dx of hypothyroidism
History
CMs
Low T4 and TSH levels
Tx of hypothyroidism
Lifelong replacement therapy of T4 and T3 (low and slow dose)
Thyroid perioxidase antibody (Hashimoto’s)
What is hyperthyroidism
Thyroid is too active or too much TSH.
Graves disease - thyroid stimulating immunoglobins increase thyroid activity by stimulating TSH receptors
Toxic nodular goiter - result of a thyroid adenoma
CM of hyperthyroidism
Goitre Weight loss Fine hair Tachycardia Arrhythmia Palpations Increased appetite Anxiety Tremor Sweating Change in menstrual patterns Sensitivity to heat Fatigue Muscle weakness
Dx of hyperthyroidism
Blood tests (TSH assay, Free T4 and T3)
Radioiodine uptake test
Thyroid scan
Fine needle aspiration
Tx of hyperthyroidism
Decrease production of thyroid hormones
Medication - thionamides, methimazole, radioactive iodine, lugol’s solution
Surgery (leave some for Calcitonin production).
Radiotherapy
Radioiodine.
What is Hypoparathyroidism
Damage to parathyroid gland during thyroid surgery causing low parathyroid hormone levels
What is Hyperparathyroidism
Excess secretion of PTH from one or more parathyroid glands (primary)
Increase in PTH secondary to a chronic disease (secondary)
CM of Hypoparathyroidism
Low serum calcium levels Muscle spasms Convulsions Death by asphyxiation Tetany Paraesthesia Cardiac arrhythmias
CM of Hyperparathyroidism
Larger parathyroid secretions Hypercalcaemia Excessive bone reabsorption Kyphosis of dorsal spine Stupor Muscle weakness and flaccidity Behavioural changes Pathological fractures Kidney stones
Dx of Hyperparathyroidism
Excluding all other reasons for hypercalcaemia
Tx of Hypoparathyroidism
Alleviation of hypocalcaemia
Calcium
Vitamin D
Tx of Hyperparathyroidism
Surgical removal of adenoma
Diuretics
Removal of PT glands
Increase fluids
Effect of ageing on endocrine system
Atrophy
Weight loss
Vascular changes
Decreased secretion and metabolism of hormones
Changes in receptor binding and intracellular responses
