Pituitary Disorders

Growth Hormone excess in childhood (before epiphyseal plate fusion) causes gigantism — proportionate excessive height. In adults (after plate fusion), GH excess causes acromegaly — enlarged hands, feet, jaw, and facial features with no increase in height. Pituitary dwarfism from GH deficiency produces proportionate short stature with normal intelligence. Prolactinoma (prolactin-secreting adenoma) presents with galactorrhoea, amenorrhoea, and hypogonadism — treated with dopamine agonists (bromocriptine) that mimic the inhibitory PIF. Diabetes insipidus from posterior pituitary ADH deficiency presents with polyuria $\frac{up to 20 L}{day of dilute urine}$ and polydipsia with normal blood glucose — distinguishing it from diabetes mellitus.

Thyroid Disorders

Graves' disease (autoimmune TSI-driven hyperthyroidism): elevated T4, suppressed TSH, exophthalmos, weight loss, increased BMR, anxiety, heat intolerance. Simple/endemic goitre (iodine deficiency): low T4, elevated TSH, enlarged thyroid — compensatory but functionally insufficient. Cretinism $\frac{congenital}{childhood hypothyroidism}$: low T4, high TSH, irreversible intellectual disability and stunted skeletal growth — preventable with newborn T4 screening. Myxoedema (adult hypothyroidism): low T4, high TSH, puffy face, low BMR, weight gain, cold intolerance — reversible with levothyroxine. Tetany after thyroidectomy: inadvertent parathyroid removal → PTH deficiency → hypocalcaemia → carpopedal spasm, positive Chvostek's sign.

Adrenal Disorders

Addison's disease (primary adrenal insufficiency): low cortisol and aldosterone → hypoglycaemia, hypotension, hyperkalaemia, and characteristic skin hyperpigmentation (excess ACTH with MSH-like activity). Emergency = Addisonian crisis (triggered by abrupt steroid withdrawal or stress without coverage). Cushing's syndrome (cortisol excess): moon face, central obesity (buffalo hump), hyperglycaemia, hypertension, immune suppression, muscle wasting. Conn's syndrome (aldosterone excess): hypertension, hypokalaemia, suppressed renin — primary hyperaldosteronism from zona glomerulosa adenoma. Phaeochromocytoma (adrenal medullary tumour): episodic hypertension, palpitations, sweating, hyperglycaemia from excess catecholamines.

Pancreatic Disorders

Type 1 DM: autoimmune destruction of β-cells → absolute insulin deficiency → hyperglycaemia, glycosuria, ketoacidosis → insulin injection mandatory. Type 2 DM: insulin resistance → relative deficiency → hyperglycaemia managed initially with diet/oral agents; associated with obesity. Both present with polyuria, polydipsia, polyphagia — but different pathophysiologies and age groups.