MD1010 - ENDO: Endocrine Disorders

Details around the disorders of the endocrine system as at JCU MBBS MD1010 in 2026

Grave’s disease

Hyperthyroidism; an autoimmune condition where circulating TSH receptor autoantibodies (thyroid stimulating immunoglobulins or TSI) lead to the overstimulation of the thyroid gland causing excessive thyroid hormone production. 60-80% of hyperthyroidism and leads to goiter

TSH producing thyrotropic adenoma

hyperthyroidism; increased TSH and T3/T4

toxic multinodular goiter (MNG)

hyperthyroidism; thyroid nodules are abnormal growths within the thyroid gland, focal and/or diffuse hyperplasia of thyroid follicular cells

hyperthyroidism

a condition of increased thyroid gland function; increased synthesis and secretion of thyroid hormones; increased basal metabolic rate, weight loss, increased heat production and intolerance, increased cardiac output, exophthalmos, insomnia, diarrhoea, tachycardia, fine tremor, muscle weakness

exophthalmos

hyperthyroidism; grave’s ophthalmopathy/thyroid associated ophthalmopathy; abnormal protrusion of one or both eyeballs forward out of the eye socket; TSH autoantibodies bind to TSH receptor antigen on cells, causes retroorbital oedema

oligomenorrhea

infrequent or irregular menstrual periods

hypothyroidism

a condition in which the thyroid gland is underactive; results in a deficiency of the thyroid hormones; decreased metabolic rate, weight gain, decreased heat production leading to cold sensitivity, decreased cardiac output, lethargy, myxoedema

myxoedema

severely advanced hypothyroidism or the specific skin swelling it causes

hashimoto thyroiditis

hypothyroidism; active B lymphocytes produce antibodies towards thyroid peroxidase and thyroglobulin, leading to a destruction of thyroid tissue; most common form of hypothyroidism

congenital hypothyroidism

hypothyroidism; absent or ectopic thyroid gland, dyshormonogenesis, TSH-R mutation

dyshormonogenesis

hypothyroidism; a rare, inherited group of disorders where the thyroid gland is present but fails to produce enough thyroid hormones due to genetic defects in the synthesis pathway

secondary hypothyroidism

hypothyroidism; pituitary disorders leading to TSH deficiency

tertiary hypothyroidism

hypothyroidism; hypothalamic disorders leading to TRH deficiency

iodine deficiency

hypothyroidism; lack of adequate iodine in the diet leading to nontoxic goiter or endemic goiter

signs and symptoms of hypothyroidism

dry, coarse skin; cool peripheral extremities; puffy face, hands, and feet (myxoedema); bradycardia; peripheral oedema; slow/delayed reflexes; feeling cold; tiredness, weakness; poor memory, difficulty concentrating; constipation; weight gain; hoarse voice; oligomenorrhea or amenorrhea

goiter

any abnormal enlargement of the thyroid gland; caused by biosynthetic defects, iodine deficiency, autoimmune diseases, or nodular diseases; readily palpable and highly visible; endemic most common; endemic, diffuse, nodular, toxic, non-toxic

endemic goiter

iodine deficiency

diffuse goiter

diffusely enlarged goiter; grave’s disease and hashimoto thyroiditis

nodular goiter

irregular enlarged thyroid due to nodule formation; toxic multinodular goiter

toxic goiter

increased thyroid hormone production

non-toxic goiter

iodine deficiency but enlarged thyroid

cretinism

hypothyroidism; a complication of severe, untreated congenital hypothyroidism; leads to impaired development of the brain and skeleton, results in skeletal abnormalities; condition of severely stunted mental and physical growth

growth hormone insufficiency

GH hyposecretion; relatively uncommon; increase in body fat and loss of muscle strength; treated with daily injections of recombinant GH

excess growth hormone

GH hypersecretion; most often caused by a secretory tumour (adenoma) of the pituitary somatotroph cells; exaggeration of normal GH physiological effects; diabetogenic effects contributes to increased cardiovascular risk

causes of growth hormone deficiency

GH secretion reduced; GH-stimulated IGF production decrease; IGF action decrease

growth hormone deficiency before puberty

individuals relatively well proportioned with normal intelligence; if only GH deficiency life-span is unaffected; GH-induce lipolysis is lost, leading to obesity

growth hormone deficiency and panhypopituitarism

person affected may not mature sexually and be infertile

dwarfism

GH deficiency; before puberty; growth is severely impaired; decreased GH secretion leads to normal sexual maturity, normal intelligence; panhypopituitarism leads to gonadotropic hormone deficiency, may not mature sexually and remain infertile; metabolic abnormalities leading to hypoglycaemia, insulinopenia, and increased insulin sensitivity

hypoglycaemia

a condition where blood glucose level drops to abnormally low levels, below 4mmol/L

insulinopenia

a severe deficiency in insulin secretion by the pancreas

laron dwarfism or laron syndrome

genetic defect in the expression of the GH receptor; plasma GH concentration is normal or elevated but the GH receptors are unresponsive due to loss-of-function mutations; characterised by the absence of or decrease in normal GH receptors by normal or elevated GH concentration; IGFs not produced in response to GH

symptoms of laron dwarfism or laron syndrome

reduce muscle strength and endurance; hypoglycaemia in infancy; delayed puberty; small genitals; short limbs; obesity

african pygmies

decreased IGF-I formation; normal plasma GH levels; low values of baseline serum GH-binding protein (GHBP) and IGF-I; does not exhibit normal rise in IGF during puberty; lack both pubertal serum IGF-I surge and growth spurt

gigantism

excessive GH secretion before puberty; caused by acidophilic tumour; increased GH before epiphyseal plates are fused, leading to height increases, increase in body weight; all body tissues grow rapidly, including bones; hyperglycaemia, glucose intolerance, hyperinsulinemia; beta cells in pancreas prone to degeneration; panhypopituitarism eventually develops; cardiovascular problems including cardiac hypertrophy

hyperglycaemia

overproduction of glucose by the liver and decreased removal of glucose from the blood; high blood glucose concentration over 15mmol/L; increased utilisation of fast and proteins

hyperinsulinemia

a condition where there is higher-than-normal levels of insulin circulating in the blood

acromegaly

excessive GH secretion at or after the epiphyses close; cartilage and membranous bones continue to grow, resulting in deformities; soft tissue growth leading to cardiovascular problems, and cardiac hypertrophy; enlargement of membranous bones, cranium, bosses of forehead, jaw bones, parts of vertebrae; increase in the growth of the nose, ears, and mandible, producing prognathism

prognathism

a dental and skeletal condition where the lower or upper jaw protrudes forward, often resulting in an underbite or misaligned teeth

symptoms of acromegaly

change in face or jaw; bite has changed or teeth are more spaced; enlarged hands and/or feet; excessive sweating; heavy snoring or daytime sleepiness; tingling or numbness in both hands; carpal tunnel syndrome; skin becoming more oily, thicker, and hairier; can cause arthritis, diabetes, hypertension

vitamin D deficiency

leads to rickets in children and osteomalacia in adults

rickets

growth of long bones is abnormal, with weakened bones leading to bowing of extremities and deformities of the rib cage

osteomalacia

characterised by poorly mineralised osteoid, bone pain, and increased fracture risk

primary hyperparathyroidism

excess PTH secretion; tumour of the parathyroid gland, parathyroid adenomas, or hyperplasia; increased calcium in the ECF’ extensive decalcification of bone, leading to hypercalcemia and hypercalciuria; large cystic areas in bone, leading to bone disease - osteitis fibrosa cystica; high serum calcium levels leading to decrease in neuromuscular excitability, increased psychological disorders associated with hypercalcemia (depression, mental confusion, fatigue), cardiovascular symptoms (palpitations, arrhythmias, and hypertension), muscle weakness and decreased muscle tone, kidney stones

secondary hyperparathyroidism

excess PTH secretion; compensation for hypocalcaemia, complication that occurs in chronic renal failure where damaged kidneys are unable to produce sufficient 1,25 DHCC and there is a moderate decrease in ionised Ca²⁺ leading to a greater synthesis and secretion of PTH; pseudohypoparathyroidism

pseudohypoparathyroidism

secondary hyperparathyroidism; rare, familial disorder characterised by tissue resistance to PTH; non-functioning PTH receptor due to a decrease in levels of guanine nucleotide-binding protein, Gs; increased PTH secretion and low serum calcium levels; congenital defects of the skeleton, including shorted metacarpal and metatarsal bones

hypoparathyroidism

lack of sufficient PTH from the parathyroid glands; decreased bone resorption, leading to decreased osteocytic and osteoclastic activities; decreased calcium in the ECF, leading to hypocalcaemia, increased nervous system excitability, increased neuronal membrane permeability to sodium ions, spontaneous nerve impulses from peripheral nerves to skeletal muscles, tetanic muscle contractions and spasm of the laryngeal muscles, seizures

hypercalcaemia

a condition in which the calcium level in the blood becomes too high; extreme thirst, frequent urination, nausea, vomiting, constipation, muscle weakness, confusion, and bone pain

hypocalcaemia

a condition where the level of calcium in the blood is abnormally low; leads to increased neuromuscular excitability (tetany), laryngeal stridor, cardiac effects where repolarisation is delayed and there is prolongation of the QT interval, dermatologic effects where the skin is often dry and flaky with brittle nails, carpopedal spasm, where there is tetany in the hand (Trousseau sign of latent tetany), Chvostek’s sign, where there is twitching of facial muscles in response to tapping over the area of the facial nerve

diabetes mellitus

a condition where there is too much glucose in the blood; most of common of all endocrine disorders; caused by a defect in insulin secretion and/or action; causes abnormalities in carbohydrate, fat, and protein metabolism and a variety of complications

risk factors for diabetes mellitus

central obesity; hypertension; low HDL, high triglycerides; smoking; family history; inactive lifestyle

factors increasing the prevalence of diabetes mellitus

increasing age; sedentary lifestyle; increasing obesity; unhealthy diet

types of diabetes mellitus

type 1, characterised by beta cell destruction leading to insulin deficiency; type 2, characterised by a progressive insulin secretory defect on the background of insulin resistance, gestational, characterised by any degree of glucose intolerance with onset or first recognition during pregnancy

type 1 diabetes mellitus

insulin dependent diabetes mellitus; characterised by the destruction of beta cells that produce insulin, resulting in insulin dependence; autoimmune and idiopathic disease; ketosis prone; usually detected before 30 years old with peak incidence in 11-13 years old (can occur at any age); usually involves ketonuria, polyuria and polydipsia, weight loss, family history of autoimmune disease, rapid onset of symptoms; increased levels of ketoacids cause a form of metabolic acidosis called diabetic ketoacidosis; undetectable C-peptide

effects of insulin deficiency

decreased glucose uptake, increased protein catabolism, and increased lipolysis leading to hyperglycaemia, glycosuria, osmotic diuresis, electrolyte depletion, increased plasma amino acids, nitrogen loss in urine, increased plasma free fatty acids, ketogenesis, ketonuria, ketonemia, dehydration, acidosis, and coma or death

type 2 diabetes mellitus

non-insulin-dependent diabetes mellitus; often associated with obesity; hyperglycaemia due to decreased insulin action and increased insulin production, leading to beta cell failure; insulin dependence in chronic stage; commonly detected after 40 years old; most common diabetes (more than 90% of diabetes is T2DM); insulin resistance where insulin is secreted normally but cannot activate receptors in the target cells; positive family history in 30% of patients; involves insidious onset of tiredness, thirst, polyuria and nocturia, no ketoacidosis, frequent infections, no recent weight loss, detectable C-peptide

insulin resistance

impaired biological response to insulin; primary defect in the majority of T2DM patients; caused by obesity, excess cortisol, excess growth hormone, pregnancy, polycystic ovarian syndrome (PCOS)

glycosuria

more glucose to filter in the kidneys; at glucose concentrations above 10mmol/L; glucose appears in urine

symptoms of diabetes mellitus

polyphagia; polyuria; polydipsia; nocturia; dry skin; itchy skin (pruritis); skin infections; slow healing of cuts; burred vision; malaise; weight loss; numbness or tingling in feet

pheochromocytoma

rare, catecholamine-secreting tumour originating from chromaffin cells in the adrenal medulla; results in excessive production and release of catecholamines; increased secretion of of catecholamines, norepinephrine and epinephrine in response to sympathetic nervous system stimulation; catecholamines increase heart rate, blood pressure, and glucose release from the liver, leading to hypertension, headache, tachycardia, diaphoresis (perspiration), tremor, nervousness, pallor, fatigue, hypermetabolic state with fever and weight loss; treated with sympathetic nervous system blocking medications and surgical removal of tumour

adrenocortical hyperfunction

hypersecretion of three types of corticosteroids; Cushing’s syndrome, characterised by excess glucocorticoids and chronic hypercortisolism; Conn’s syndrome, characterised by excess mineralocorticoids and primary hyperaldosteronism; Adrenogenital syndrome, characterised by excess adrenal sex steroids and adrenal virilism

Cushing’s syndrome

hypercortisolism; most commonly caused by pharmacologic use of exogenous corticosteroids; blanket term for excessive cortisol production; includes pituitary, adrenal, ectopic, and latrogenic; primary is disease of the adrenal cortex, secondary is hyperfunction of anterior pituitary ACTH-secreting cells, tertiary is hypothalamic dysfunction or injury

signs and symptoms of cushing’s syndrome

weight gain with excess total body fat, central or truncal obesity; thin arms and legs; buffalo hump and fat over shoulders; rounded, oedematous face; wasting and thinning of muscle due to increased protein breakdown; purple striae on abdominal wall; easy bruisability of thin skin to minor trauma; enhance bone resorption (osteoporosis), negative calcium balance, loss of bone matrix, osteonecrosis; hypertension, oedema, and congestive heart failure; depressed immune function; glucose intolerance and hyperglycaemia

pituitary Cushing’s syndrome or Cushing’s disease

60-70% of cases of hypercortisolism; a functional pituitary adenoma leading to excessive secretion of ACTH; hypothalamic (CRH) origin of excessive ACTH without pituitary lesions; lesion in pituitary gland (corticotroph adenoma or multiple corticotroph microadenoma); characterised by elevated ACTH levels

adrenal Cushing’s syndrome

20-25% of cases of cushing’s syndrome; disease in one or both adrenal glands, adrenal cortical adenoma or carcinoma; cortical hyperplasia; characterised by low ACTH levels

ectopic Cushing’s syndrome

10-15% of cases of Cushing’s syndrome; ectopic ACTH secretion (ACTH secretion from regions other than anterior pituitary); non-endocrine tumours secreting ACTH, carcinoma of the lung or pancreatic tumours secreting ACTH; increased plasma ACTH

latrogenic Cushing’s syndrome

prolonged therapeutic administration of high doses of glucocorticoids or ACTH; therapeutic doses of cortisol in organ transplant recipients may cause CS

hyperplasia

the increase in the number of cells in a tissue or organ

Addison’s disease

primary adrenal insufficiency in which the levels of both mineralocorticoids and glucocorticoids are extremely low; an autoimmune disease that involves bilateral destruction of the adrenal cortex by anti-adrenal antibodies shown to be attached to ACTH receptor sites; majority of cases due to tuberculosis or autoimmune chronic destruction of the gland; adrenocortical plasma deficiency diagnosis, with decreased plasma cortisol levels, ACTH high in primary but low in secondary

clinical manifestations of addison’s disease

hyperpigmentation in skin creases, scars, and gums due to ACTH competing for MC1R in melanocytes, mineralocorticoid deficiency causing severe renal sodium chloride wasting and hyperkalaemia; hyponatraemia or salt craving; hypoglycaemia; reduce cardiac output, reduce blood volume, and decreased blood pressure; oesinophilia and lymphocytosis; androgen deficiency - loss of body hair, decreased libido, and amenorrhea in women, sexual dysfunction in men

hyperkalaemia

a serious condition where blood potassium level is too high (typically above 5mEq/L. It is most commonly caused by kidney disease, certain medications, or severe dehydration

hypokalaemia

a condition where blood potassium levels fall below the normal range of 3.5mEq/L

hyponatraemia

occurs when the sodium level in blood drops below normal limits (<135mmol/L)

hypernatraemia

occurs when sodium level in blood increase above normal limits (>145mmol/L)

hypersecretion of adrenal androgens

enzyme blockage that decreases cortisol synthesis and increases ACTH secretion; most commonly due to a deficiency of the enzyme 21-hydroxylase; high ACTH causes adrenal hyperplasia and drives adrenal androgen production by the zona reticularis, causing severe symptoms due to inadequate circulating cortisol; distortion of external genitalia in girls and precocious puberty in boys; hirsutism, oligomenorrhea, deepening of the voice, hypertrophy of clitoris and ovarian dysfunction in females (adrenogenital syndrome)

21-hydroxylase deficiency

accounts for 95% of genetic abnormalities in adrenal steroid hormone synthesis; the enzyme converts progesterone to deoxycorticosterone and 17-hydroxyprogesterone to 11-deoxycortisol, so when there is a deficiency, pregnenolone is shunted to the DHEA-androstenedione pathway leading to more androgens and virilisation; cortisol production inhibited; sex steroid production increases; increase in DHEA, androstenedione, testosterone, estrone, oestriol, oestradiol

clinical dehydration

low TBW relative to body solutes; ECF volume contraction; severity classified by % of body weight lost; caused by inadequate water intake due to anorexia, dysphagia or impaired consciousness; excessive water loss due to vomiting and diarrhoea, polyuria, burns, haemorrhage, or fever; third-spacing due to pancreatitis, bowel obstruction, or peritonitis; treated with volume resuscitation guided by severity and aetiology

mild dehydration

3-5% of body weight lost; characterised by thirst, dry mucosa, lower urine output

moderate dehydration

6-9% of body weight lost; characterised by tachycardia, orthostatic drop, oliguria

severe dehydration

>10% of body weight lost; characterised by haemodynamic instability, end-organ hypoperfusion

oedema

clinically detectable accumulation of interstitial fluid; caused by disruptions of the Starling forces; increased capillary hydrostatic pressure, decreased plasma colloid osmotic pressure, increased capillary permeability, or lymphatic obstruction

classifications of oedema

pitting oedema, where indentation persists after firm pressure from free interstitial fluid and low protein, graded 1 to 4 by depth and recovery time and caused by HF, renal disease, venous insufficiency or cirrhosis; non-pitting oedema, where there is no indentation and it is protein rich or solid tissue

lymphoedema

non-pitting oedema; blocked lymph drainage; filariasis, post surgical

myxoedema

non-pitting oedema; mucopolysaccharide deposition in hypothyroidism

lipoedema

non-pitting oedema; abnormal subcutaneous fat

oedema pathophysiology

increased hydrostatic pressure; decreased oncotic pressure; increased vascular permeability; increased sodium retention, lymphatic blockage

diabetes insipidus

syndrome that results when there is a vasopressin deficiency or when the kidneys fail to respond to vasopressin; characterised by the excretion of abnormally large volumes of dilute urine and excessive thirst; hypothalamic, caused by decreased ADH release; nephrogenic, caused by decreased renal responsiveness to ADH; dipsogenic, caused by excessive water drinking; gestational, where there is an ADH deficiency only during pregnancy; causes excessive urination, drinking large amounts, dehydration, normal blood glucose

hypothalamic diabetes insipidus

neurogenic, central, or cranial DI; partial or complete lack of ADH secretion; caused by head injury, surgery, trauma, inflammation, infection, or hypothalamic tumours; plasma ADH levels are low and large volumes of dilute urine is secreted

nephrogenic diabetes insipidus

inability of the kidneys to respond to ADH; the collecting ducts are partially or completely unresponsive to ADH; caused by congenital defects in the V2 receptor; urine output is increased, but the plasma ADH level is usually higher than normal

gestational diabetes insipidus

deficiency of ADH only during pregnancy

dipsogenic diabetes insipidus

increased thirst mechanism or increased fluid/water intake

syndrome of inappropriate antidiuretic hormone

too much ADH secretion with inappropriate water retention and decreased blood sodium; caused by brain injury or tumour production of ADH, malignancies of other organs such as lung or pancreas; characterised by plasma ADH levels inappropriately high for existing osmolality; plasma osmolality is low; kidneys form concentrated urine; inability to produce dilute urine leads to dilutional hyponatraemia; causes headaches, nausea, vomiting, confusion, convulsions

Conn’s syndrome

hyperaldosteronism; overproduction of aldosterone; caused by adrenocortical adenoma producing aldosterone, bilateral adrenal hyperplasia in children, or adrenal carcinoma; involves primary hyperaldosteronism and secondary hyperaldosteronism; involves excessive sodium reabsorption and potassium excretion, leading to water retention, arterial hypertension, hypokalaemia, muscle weakness, cardiac arrhythmia

primary hyperaldosteronism

most commonly occurs as a result of adrenal hyperplasia and aldosterone-producing adenomas; associated with low plasma renin; most common cause of adrenal-mediated hypertension

secondary hyperaldosteronism

associated with high plasma renin levels; stimulation of angiotensin II and aldosterone production

hypoaldosteronism

isolated deficiency of aldosterone; caused by reduced renin, congenital defect where there is a deficiency of the enzyme for renin synthesis, prolonged administration of heparin leading to the reduction in both the number and affinity of the angiotensin-II receptors in the zona glomerulosa, excision of aldosterone secreting tumour; causes hypotension, hyperkalaemia, and metabolic acidosis

general adaptation syndrome

universal response to stressors; occurs in the nervous and endocrine systems; the effect is a general systemic reaction to a stressor where the physical manifestations are coordinated and dependent on each other; has three stages, alarm reaction/shock stage, stage of resistance/counter shock, stage of exhaustion

GAS - alarm reaction

characterised by a generalised stimulation of the sympathetic nervous system, resulting in the release of catecholamines; is rapid, physical, or psychological; leads to increased sympathetic-adrenal activation, with an increased release of epinephrine, increased heart rate and constriction of blood vessels to viscera and skin, increased blood supply to the heart and muscles leading to increased blood pressure, increased conversion of glycogen to glucose, sweating, airway dilation, and decreased activities in the digestive system and reproductive system; only finishes when the body runs out of raw materials

GAS - adaptation or stage of resistance

body adapts to the stressors, leading to the body changing to reduce the stress effects; involves hormonal responses during adaptation; cortisol causes lipolysis, gluconeogenesis, protein catabolism, increased blood vessel sensitivity, and decreased inflammation

GAS - stage of exhaustion

stage during which resources are depleted and signs of wear and tear or systemic damage appear; decreased body energy and immunity; adrenal exhaustion; decreased blood sugar level; decreased stress tolerance leading to mental and physical exhaustion, and illness