Endocrine Disorders

Pituitary Adenoma

  • Applies pressure to the optic nerve, causing defects in the visual field
  • Increases intracranial pressure, causing headaches, nausea and vomiting (because of pressure onto chemoreceptor vomiting centre)

Growth Hormone Disorders

  • Dwarfism - too little growth hormone, short stature
  • Gigantism - too much growth hormone before puberty, tall stature
  • Acromegaly - too much growth hormone after puberty, tall stature

Anti-Diuretic Hormone Disorder

  • Diabetes insipidus - too little ADH causing polyuria due to:
    • Destruction of pituitary gland
    • Impaired function or damage to hypothalamus
    • Sporadic (irregular) defects in ADH synthesis (genetic)

Thyroid Gland Disorders

  • Hypothyroidism: cretinism (congenital) or myxoedema (acquired)
  • Hyperthyroidism: Grave's disease, multi-nodular goitre, adenoma of the thyroid, thyroiditis and thyroid storm
  • Goitre: increase in the thyroid gland, mostly commonly being an irregular multinodar goitre, due to
    • Hypothyroidism: due to iodine deficiency or Hashimoto's disease
    • Hyperthyroidism: due to pituitary adenoma

Hypothyroidism

  • Coarse, brittle hair
  • Loss of hair
  • Puffy face
  • Normal or small thyroid
  • Heart failure
  • Weight gain
  • Constipation
  • Doughy, dry skin
  • Muscle weakness
  • Edema of the extremities

Congenital Hypothyroidism

Common cause of preventable mental retardation which becomes cretinism without treatment

Cause: congenital lack of the thyroid gland, abnormal synthesis of the thyroid hormones or congenital thyroid stimulating hormone deficiency

Age: appears at birth but symptoms arise later without treatment

Preventative strategy: screening at 1-5 days of age for presence of T4 hormone and thyroid stimulating hormone

Acquired Hypothyroidism

Age: older children and adults

Cause: thyroidectomy or ablation, drugs, iodine deficiency or an autoimmune disorder e.g. Hashimoto thyroiditis

Secondary cause: impaired function of the anterior pituitary gland

Characteristic: serum T4 decreases and serum TSH increases

Hashimoto Thyroiditis

An autoimmune disorder in which autoantibodies fight against thyroglobulin and TSH receptors.

Characteristics: decreased serum T3 and T4, increased serum TSH, hypo metabolism, cold intolerance, low heart rate, large protruding tongue, myxedematous involvement of body tissues

Result: primary hypothyroidism, type 1 diabetes mellitus, pernicious anaemia, adrenal insufficiency

Hyperthyroidism

Results in:

  • Hyper metabolism (weight loss)
  • Increased oxygen consumption
  • Increased activity of sympathetic nervous system
  • Sweating and heat intolerance
  • Fine hair
  • Exophthalmos
  • Enlarged or nodular thyroid
  • Heart failure
  • Extra heartbeats
  • Weight loss
  • Diarrhoea
  • Warm, velvety skin
  • Sweaty palms
  • Overactive reflexes
Treatment: radioactive eradication of thyroid gland, surgical removal, antithyroid drugs, ß-adrenoblockers

Grave's Disease

The abnormal stimulation of the thyroid gland by TSH-receptor antibodies (Type 2 hypersensitivity).

Result: hyperthyroidism, diffuse goitre and opthalmopathy (double vision)

Gender: women

Age: 20-40 years

Characteristics: exophthalmos (bulging eyes), opthalmopathy due to diplopia (extra ocular muscles, loss of vision due to damage optic nerve and or corneal ulceration, eyelids cannot close)

Thyroid Storm

A life-threatening extreme manifestation of thyrotoxicosis.

Cause: stress, infection, diabetic ketoacidosis, trauma or manipulation of hyperactive thyroid during thyroidectomy

Characteristics: very high fever, cardiovascular effects (tachycardia, congestive failure, angina), CNS involvement (agitation, restlessness, delirium)

Hypocalcaemia

Low blood calcium levels causing:

Characteristics: tetany, muscle cramps/spasms, convulsions, tingling sensations (paraesthesias) in hand, feet and around the mouth, cardiovascular effects, fatigue and lethargy

Hyperparathyroidism

Due to increased parathyroid secretion

Cause: adenoma, hyperplasia or carcinoma (rare)

Secondary cause: hypocalcaemia → chronic renal failure

Result: emotional disorders, muscle atrophy, pancreatitis, kidney stones, kidney calcification and bone disease

Diabetes Mellitus (DM)

Cause: imbalance between insulin availability and insulin need due to:
  • Impaired release of insulin from beta cells
  • Impaired function of insulin receptors
Consequences:
  • Microvascular: neuropathy (leads to foot ulcers and painless myocardial infarction), nephropathy, retinopathy
  • Microvascular: coronary artery disease, cerebral vascular disease and peripheral vascular disease
  • Foot ulcers: because of neuropathy (loss of fine touch, pain and proprioception causes inability to detect foot injuries)
  • Infections due to high glucose providing bacteria and fungi with a food source, as well as a lack of blood supply to areas:
    • UTIs and pyelonephritis
    • Osteomyelitis
    • Candida infections of skin and mucous membranes

Type 1 Diabetes

The immune mediated, autoimmune destruction of beta cells, induced by some type of environmental insult in genetically susceptible people.

Age: 10-12 years

Pathogenesis: destruction of beta cells leads to absolute insulin deficiency

Cause: idiopathic, genetic

Result: polyuria (glucose being filtered by glomeruli exceeds glucose being absorbed) → glycosuria and large loss of water, polydipsia (high blood glucose levels draws water from the cells), polyphagia (cellular starvation and weight loss), liver breaks down fats → ketones → ketosis (acidosis, causing a coma)

Type 2 Diabetes

Due to metabolic chances such as insulin resistance and impaired insulin secretion

Cause: age, overweight, genetic susceptibility, diet with highly processed carbohydrates

Characteristic: peripheral tissue insulin resistance and beta-cell inadequacy

Glucocorticoid Hormone Excess (Cushing's Syndrome)

There are two methods of pathogenesis for Cushing's syndrome:
  1. ACTH dependent (high blood ACTH) - stimulate release of glucocorticoids from adrenal glands due to pituitary adenoma, pituitary hyperplasia (pituitary form) or small cell carcinoma of the lung (etopic form)
  2. ACTH independent (low blood ACTH) - adrenal gland secretes cortisol without ACTH (adrenal form), meaning ACTH blood levels fall, due to adrenocortical carcinoma, hyperplasia, adenoma or steroid therapy (iatrogenic form)
Result: obesity (buffalo hump), fluid and salt retention → oedema and moon face, easy bruising, osteoporosis, acne and stretch marks

Pheochromocytoma

The most common neoplasm of the adrenal medulla, with 10% being malignant and metastasising to the liver, lymph nodes and bones.

Result: excessive catecholamine production (adrenaline, noradrenaline) → vasoconstriction, increased heart rate and contractility, glycogenolysis, gluconeogenesis, hypertensive crisis (sudden increase in blood pressure)

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