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Endocrinology

Hormones and the glands that make them: diabetes, thyroid, adrenal, pituitary and calcium disorders.

36 topics published

Introduction

Endocrinology is the study of hormones: the signals that glands release into the blood to regulate metabolism, growth, water and salt balance, bone and the response to stress. Because hormones work in feedback loops, most endocrine disease is either too much of a hormone, too little, or a gland that no longer responds to its controls.

This section starts with diabetes, the most common endocrine disease, then follows the glands in turn: the thyroid, bone and the parathyroids, the pituitary and the water-balance hormones, the adrenal glands, and finally the inherited tumour syndromes that affect several glands at once.

Every topic uses the same layout: a short summary, what you should be able to do afterwards, the mechanism, the clinical picture, tests, treatment and the traps. Doses, targets and cut-offs are checked against named guidelines and shown with their source, because guidelines and countries sometimes differ.

How to study endocrinology

Learn each gland as a loop: the brain signal, the hormone, the target and the feedback. Once you can draw the loop, the tests follow: a high hormone with a high controlling signal points to the gland above, a high hormone with a low signal points to the gland itself.

For the excess and deficiency states, learn the screening test, the confirmatory test and then the imaging, in that order. The most common traps are testing in the wrong order and reading a hormone level without the controlling hormone.

Learn the emergencies as pathways: diabetic ketoacidosis, hyperosmolar state, adrenal crisis, thyroid storm, myxoedema coma and hypoglycaemia. Practise saying the first three actions aloud, and use the check-yourself questions at the end of each topic a few days later.

This section links to renal medicine (sodium, calcium, potassium), cardiology (hypertension, lipids), gastroenterology (neuroendocrine tumours) and oncology, so follow the related links. Content here is for study and does not replace local protocols or a senior clinician's judgement.

Contents by part

The topics below are in teaching order. Each part builds on the one before it.

  1. Diabetes mellitus. Start with the commonest endocrine disease: the two types, the drugs and insulin, the acute emergencies and the long-term complications, then the metabolic syndrome that surrounds type 2 diabetes.
  2. The thyroid. How the thyroid is tested, then too much hormone, too little, inflammation and tumours of the gland.
  3. Bone and calcium. Diseases of bone strength and remodelling, and the parathyroid glands that control calcium.
  4. Pituitary and water balance. The master gland: too little of every hormone, too much growth hormone or prolactin, and the two disorders of antidiuretic hormone.
  5. The adrenal glands. Too little cortisol, tumours of the adrenal medulla, too much aldosterone, and the inherited enzyme defects of the cortex.
  6. Inherited endocrine tumour syndromes. The multiple endocrine neoplasia syndromes that tie the glands together.

Topics

  1. Type 1 diabetes mellitus

    Autoimmune destruction of insulin-producing beta cells: how type 1 diabetes shows, how it is diagnosed and staged, and how to manage and monitor it.
    Checked against sourcesVerified 28 October 2026

  2. Antihyperglycaemic drugs and insulin

    Every glucose-lowering drug class: mechanism, HbA1c, weight and hypo risk, plus insulin regimens, comorbidity-based selection and low-resource care.
    Checked against sourcesVerified 28 October 2026

  3. Type 2 diabetes mellitus

    A chronic metabolic disease of insulin resistance and relative insulin deficiency: definition, diagnosis, targets and stepwise management.
    Checked against sourcesVerified 28 October 2026

  5. Chronic complications of diabetes

    How long-standing high blood glucose damages the eyes, kidneys, nerves, heart, vessels and feet, and how to screen for and reduce that risk.
    Checked against sourcesVerified 28 October 2026

  6. Metabolic syndrome

    Metabolic syndrome: central adiposity, insulin resistance, dysglycaemia, dyslipidaemia and hypertension; criteria, causes, risks and care.
    Checked against sourcesVerified 28 October 2026

  1. Hypoglycaemia and insulinoma

    How low glucose presents, what causes it with and without diabetes, how fasting hypoglycaemia is evaluated, and how insulinoma is diagnosed and treated.
    Checked against sourcesVerified 31 October 2026

  2. Diabetes technology and monitoring

    Monitoring glucose and delivering insulin: HbA1c, blood glucose meters, CGM metrics and time in range, insulin pumps and automated insulin delivery.
    Checked against sourcesVerified 31 October 2026

  3. Obesity and weight management

    Definitions, staged assessment, lifestyle, pharmacotherapy including GLP-1 medicines, bariatric surgery, complications, special groups and low-resource care.
    Checked against sourcesVerified 31 October 2026

  4. Thyroid function tests

    How thyroid testing works: the HPT axis, interpreting TSH, free T4 and free T3, antibodies, imaging, drugs and practice in low-resource settings.
    Checked against sourcesVerified 28 October 2026

  5. Hyperthyroidism and thyrotoxicosis

    Thyroid hormone excess: how it differs from thyrotoxicosis, its causes, presentation, tests, treatment, storm and pregnancy.
    Checked against sourcesVerified 28 October 2026

  6. Hypothyroidism

    Deficient thyroid hormone: its causes, how it presents, how we diagnose it, how we treat it, and myxoedema coma.
    Checked against sourcesVerified 28 October 2026

  7. Thyroiditis

    Thyroiditis: inflammation of the thyroid gland in its several forms, with transient thyrotoxicosis, hypothyroidism, tests and treatment.
    Checked against sourcesVerified 28 October 2026

  8. Thyroid nodules and thyroid neoplasms

    Thyroid nodules and cancer: risk, ultrasound and TI-RADS, TSH and scans, FNA and Bethesda, the main cancer types, treatment and follow-up.
    Checked against sourcesVerified 28 October 2026

  10. Osteoporosis

    Osteoporosis: low bone mass and microarchitectural deterioration that lead to fragility fractures; risk factors, screening, diagnosis, and treatment.
    Checked against sourcesVerified 28 October 2026

  11. Paget disease of bone

    Paget disease of bone: focal disordered bone remodelling, phases, complications, diagnosis with alkaline phosphatase and imaging, and bisphosphonate treatment.
    Checked against sourcesVerified 28 October 2026

  12. Hyperparathyroidism

    Overactive parathyroid glands: causes, stones and bones, tests that separate it from mimics, and treatment from parathyroid surgery to dialysis care.
    Checked against sourcesVerified 28 October 2026

  14. Hypopituitarism

    Partial or complete failure of the pituitary gland to secrete one or more hormones: causes, diagnosis and replacement.
    Checked against sourcesVerified 28 October 2026

  15. Cushing syndrome

    Excess cortisol from any cause: how it produces the Cushingoid phenotype, how to screen and find the source, and how to treat it.
    Checked against sourcesVerified 28 October 2026

  16. Acromegaly

    Chronic GH excess: causes, presentation, diagnosis with IGF-1 and GH suppression, surgery, medicines, radiation and screening.
    Checked against sourcesVerified 28 October 2026

  17. Hyperprolactinaemia and prolactinoma

    Hyperprolactinaemia and prolactinoma: causes, symptoms, diagnosis and treatment, from dopamine biology to dopamine agonists, surgery, and pregnancy.
    Checked against sourcesVerified 28 October 2026

  18. Diabetes insipidus

    AVP deficiency or resistance: how central and nephrogenic diabetes insipidus cause polyuria and hypernatraemia, how to diagnose them, and how to treat them.
    Checked against sourcesVerified 28 October 2026

  20. Pituitary incidentaloma and pituitary apoplexy

    Incidentally found pituitary lesions and the bleed or infarct called pituitary apoplexy: definition, imaging, hormone work-up, visual fields, emergency.
    Checked against sourcesVerified 31 October 2026

  22. Hypogonadism and delayed puberty

    How low sex-steroid output delays puberty, how to separate testicular from pituitary failure, and how testosterone and oestrogen are used
    Checked against sourcesVerified 31 October 2026

  23. Adrenal insufficiency and adrenal crisis

    How the adrenal glands fail, how the patient looks, how to test, and how to treat adrenal crisis and lifelong replacement safely.
    Checked against sourcesVerified 28 October 2026

  24. Phaeochromocytoma and paraganglioma

    Catecholamine-secreting tumours of the adrenal medulla and paraganglia: genetics, diagnosis, preoperative blockade, surgery and lifelong follow-up.
    Checked against sourcesVerified 28 October 2026

  25. Primary hyperaldosteronism

    How excess aldosterone causes hypertension: causes, who to screen, aldosterone-to-renin ratio, confirmatory tests, subtype imaging and treatment.
    Checked against sourcesVerified 28 October 2026

  26. Congenital adrenal hyperplasia

    Autosomal recessive enzyme defects that block cortisol synthesis, leading to androgen excess and, in severe forms, salt-wasting crises.
    Checked against sourcesVerified 28 October 2026

  28. Adrenal incidentaloma

    How to work up an adrenal mass found by chance: imaging, hormones, and when to operate.
    Checked against sourcesVerified 31 October 2026

  29. Multiple endocrine neoplasia

    MEN1 (menin), MEN2A and 2B (RET) and MEN4 (CDKN1B): tumour spectra, inheritance, genetic testing, surveillance, RET-risk thyroidectomy and management.
    Checked against sourcesVerified 28 October 2026

  30. Neuroendocrine tumours and carcinoid

    Neuroendocrine tumours (NETs): classification, carcinoid syndrome, diagnosis, imaging, and somatostatin analogue therapy.
    Checked against sourcesVerified 31 October 2026