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High-Yield Endocrinology and Diabetes for Medical Exams
High-yield endocrinology revision: diabetes diagnosis and drugs, DKA and HHS, thyroid, adrenal, pituitary, calcium disorders, diagnostic tests and exam traps.
Endocrinology is a favourite exam subject because it is logical: hormones have feedback loops, and most questions ask you to read a pattern of results and name the gland at fault. Diabetes adds a large block of pharmacology and emergencies. This guide is exam revision, not treatment advice.
Diabetes mellitus: diagnosis
| Test | Diabetes threshold | Prediabetes / intermediate range (varies by guideline) |
|---|---|---|
| Fasting plasma glucose | 7.0 mmol/L (126 mg/dL) or more | 5.6โ6.9 mmol/L (ADA) or 6.1โ6.9 mmol/L (WHO) |
| 2-hour glucose on 75 g OGTT | 11.1 mmol/L (200 mg/dL) or more | 7.8โ11.0 mmol/L |
| HbA1c | 48 mmol/mol (6.5%) or more | 39โ47 mmol/mol (ADA) or 42โ47 (UK) |
| Random glucose with symptoms | 11.1 mmol/L (200 mg/dL) or more |
Without symptoms, the diagnosis needs two abnormal results (same test repeated or two different tests). Trap: HbA1c is unreliable in conditions that change red cell lifespan (haemoglobinopathies, haemolysis, recent transfusion, pregnancy) and in suspected type 1 diabetes developing rapidly.
Type 1 vs type 2
Type 1 is autoimmune beta-cell destruction: usually younger, often lean, ketosis-prone, with positive autoantibodies (GAD, IA-2, ZnT8) and low C-peptide. Type 2 is insulin resistance with relative insulin deficiency. Remember monogenic diabetes (MODY) in a young patient with strong family history and no ketosis, and latent autoimmune diabetes in adults.
Diabetes drugs
| Class | Example | Mechanism | Key points |
|---|---|---|---|
| Biguanide | Metformin | Reduces hepatic glucose output | Usual first line in type 2; GI upset; caution in severe renal impairment; B12 deficiency |
| SGLT2 inhibitor | Empagliflozin, dapagliflozin | Urinary glucose loss | Heart failure and CKD benefit; genital infection, euglycaemic DKA |
| GLP-1 receptor agonist | Semaglutide, liraglutide | Incretin effect, slows gastric emptying | Weight loss, cardiovascular benefit; nausea |
| DPP-4 inhibitor | Sitagliptin | Prolongs incretins | Weight-neutral, low hypoglycaemia risk |
| Sulfonylurea | Gliclazide | Insulin secretion | Hypoglycaemia, weight gain |
| Thiazolidinedione | Pioglitazone | Insulin sensitiser | Fluid retention, avoid in heart failure; bladder cancer and fracture risk |
| Insulin | Basal, bolus, mixed | Replacement | Hypoglycaemia, weight gain |
Major guidelines now steer drug choice by comorbidity: in type 2 diabetes with established cardiovascular disease, heart failure or chronic kidney disease, an SGLT2 inhibitor or GLP-1 receptor agonist with proven benefit is recommended early, independent of HbA1c.
Diabetic emergencies
| Feature | Diabetic ketoacidosis (DKA) | Hyperosmolar hyperglycaemic state (HHS) |
|---|---|---|
| Typical patient | Type 1, any age | Older, type 2 |
| Onset | Hours to a day | Days |
| Glucose | Raised (can be near normal on SGLT2 inhibitors) | Usually very high |
| Ketones | High | Low or absent |
| pH / bicarbonate | Acidotic | Usually not acidotic |
| Osmolality | Variable | Very high |
| Main danger | Acidosis, hypokalaemia during treatment, cerebral oedema in children | Severe dehydration, thrombosis |
DKA management themes
- Intravenous fluids first.
- Fixed-rate intravenous insulin infusion, weight-based; continue long-acting basal insulin.
- Monitor potassium closely and replace it in the fluids; insulin shifts potassium into cells.
- Add glucose when blood glucose falls, while continuing insulin until ketones clear.
- Treat the trigger: infection, missed insulin, new diagnosis, myocardial infarction.
In HHS, fluid replacement is the key step, and glucose and sodium must fall gradually.
Hypoglycaemia
If conscious and able to swallow: fast-acting oral glucose. If not: intravenous glucose or intramuscular glucagon. Sulfonylurea-induced hypoglycaemia can recur and needs observation.
Thyroid
| TSH | Free T4 | Interpretation |
|---|---|---|
| High | Low | Primary hypothyroidism (Hashimoto's most common in iodine-sufficient regions) |
| High | Normal | Subclinical hypothyroidism |
| Low | High | Primary hyperthyroidism |
| Low | Normal | Subclinical hyperthyroidism, or T3 toxicosis (check T3) |
| Low or normal | Low | Secondary (pituitary) hypothyroidism or sick euthyroid |
Hyperthyroidism causes
- Graves disease: diffuse goitre, eye signs, pretibial myxoedema, TSH receptor antibodies.
- Toxic multinodular goitre and toxic adenoma: nodular uptake on scan.
- Thyroiditis (subacute, postpartum, silent): low uptake on scan; painful neck in subacute (de Quervain) thyroiditis.
- Amiodarone and iodine: either hypo- or hyperthyroidism.
Treatment options: antithyroid drugs (carbimazole; propylthiouracil in the first trimester of pregnancy), radioactive iodine (contraindicated in pregnancy and active severe eye disease), or surgery. Beta blockers control symptoms.
Thyroid storm: fever, tachycardia, agitation and organ dysfunction; managed with beta blockers, antithyroid drugs, then iodine, and steroids, with supportive care.
Hypothyroidism
Levothyroxine, titrated to TSH. Start low in older patients and those with ischaemic heart disease. Requirement rises in pregnancy. Myxoedema coma (hypothermia, reduced consciousness) is an emergency.
Thyroid nodules
Ultrasound features guide fine-needle aspiration. Papillary carcinoma is the most common thyroid cancer; medullary carcinoma is associated with calcitonin and MEN2.
Adrenal disorders
| Condition | Key features | Screening / confirmation |
|---|---|---|
| Cushing syndrome | Central obesity, striae, proximal myopathy, hypertension, hyperglycaemia | Overnight dexamethasone suppression, late-night salivary cortisol, 24-hour urinary cortisol; ACTH to localise |
| Addison disease | Fatigue, weight loss, hyperpigmentation, hypotension, hyponatraemia, hyperkalaemia | Short Synacthen (ACTH stimulation) test |
| Primary hyperaldosteronism | Hypertension, hypokalaemia (not always), alkalosis | Aldosterone:renin ratio, then confirmatory testing |
| Phaeochromocytoma | Episodic headache, sweating, palpitations, hypertension | Plasma or urinary metanephrines |
Adrenal crisis: shock, often with vomiting and hyponatraemia, in someone with adrenal insufficiency or on long-term steroids. Give intravenous or intramuscular hydrocortisone immediately and fluids; do not wait for test results.
Phaeochromocytoma trap: before surgery, alpha blockade comes first, then beta blockade. A beta blocker alone can trigger a hypertensive crisis.
Exogenous glucocorticoids are the most common cause of Cushing syndrome overall.
Pituitary
- Prolactinoma: galactorrhoea, amenorrhoea, erectile dysfunction, headache; first-line treatment is a dopamine agonist (cabergoline).
- Acromegaly: enlarged hands and feet, coarse features, sweating; screen with IGF-1, confirm with failure of growth hormone suppression on OGTT.
- Pituitary apoplexy: sudden headache, visual loss and ophthalmoplegia; give steroids urgently.
- Bitemporal hemianopia: compression of the optic chiasm.
Diabetes insipidus vs SIADH
| Feature | Diabetes insipidus | SIADH |
|---|---|---|
| Urine | Large volume, dilute | Concentrated |
| Serum sodium | High or high-normal | Low |
| Key test | Water deprivation test with desmopressin | Low serum osmolality with inappropriately concentrated urine in a euvolaemic patient |
Cranial DI responds to desmopressin; nephrogenic DI (lithium, hypercalcaemia) does not.
Calcium and bone
| Calcium | PTH | Likely cause |
|---|---|---|
| High | High or inappropriately normal | Primary hyperparathyroidism |
| High | Low | Malignancy (PTH-related peptide or bone metastases), myeloma, sarcoidosis, vitamin D excess |
| Low | High | Vitamin D deficiency, chronic kidney disease (secondary hyperparathyroidism) |
| Low | Low | Hypoparathyroidism (often after thyroid or parathyroid surgery), magnesium deficiency |
Severe hypercalcaemia ("bones, stones, abdominal groans and psychic moans"): intravenous fluids first, then bisphosphonate. Hypocalcaemia signs: perioral tingling, Chvostek and Trousseau signs, prolonged QT.
Multiple endocrine neoplasia
- MEN1: parathyroid, pituitary, pancreatic tumours.
- MEN2A: medullary thyroid carcinoma, phaeochromocytoma, parathyroid hyperplasia.
- MEN2B: medullary thyroid carcinoma, phaeochromocytoma, mucosal neuromas, marfanoid habitus.
Common exam traps
- Starting insulin in DKA without checking potassium.
- Stopping long-acting insulin during a DKA infusion.
- Using HbA1c for diagnosis in pregnancy or haemoglobinopathy.
- Giving a beta blocker alone in phaeochromocytoma.
- Delaying hydrocortisone in suspected adrenal crisis to complete testing.
- Reading low TSH with low T4 as hyperthyroidism (think pituitary).
- Using radioactive iodine in pregnancy.
How to revise
Draw each axis (hypothalamus, pituitary, target gland) and practise predicting hormone patterns for every lesion. Then drill result-interpretation questions. MediFlow Exam Prep questions include lab-pattern vignettes with explanations. Pair this guide with high-yield renal and electrolytes and high-yield pharmacology.
Summary
- Know the diabetes diagnostic thresholds and when HbA1c fails.
- Choose type 2 diabetes drugs by comorbidity as well as glucose.
- DKA: fluids, insulin, potassium, trigger.
- Read thyroid and calcium results as patterns, not single numbers.
- Adrenal crisis and pituitary apoplexy need steroids before confirmation.
Practice questions in MediFlow Exam Prep
Daily questions with explanations, a study plan and mock exams. Start free.
App StoreFrequently asked questions
What are the diagnostic criteria for diabetes?
Major guidelines use fasting plasma glucose of 7.0 mmol/L (126 mg/dL) or more, a 2-hour glucose of 11.1 mmol/L (200 mg/dL) or more on an oral glucose tolerance test, HbA1c of 48 mmol/mol (6.5%) or more, or a random glucose of 11.1 mmol/L or more with symptoms. Without symptoms, a second abnormal test confirms the diagnosis.
What is the first step in DKA management?
Intravenous fluid resuscitation, followed by a fixed-rate insulin infusion, with close potassium monitoring and replacement. Potassium must be checked before and during insulin therapy because insulin drives potassium into cells.
How do exams test thyroid function tests?
By pairing TSH and free T4 patterns with a cause: high TSH and low T4 in primary hypothyroidism, low TSH and high T4 in primary hyperthyroidism, and inappropriately normal or low TSH with low T4 in pituitary disease.
How is Cushing syndrome screened for?
With an overnight dexamethasone suppression test, late-night salivary cortisol or 24-hour urinary free cortisol. ACTH then separates ACTH-dependent from adrenal causes.
Is this guide clinical advice?
No. It is exam revision material. Diabetes and endocrine treatment in practice follows current guidelines and specialist advice.
Educational content only, not individual medical, legal or immigration advice. Fees, formats and rules change: always confirm with the responsible authority before you apply.
MediFlow Editorial Team
Medical education editors
The MediFlow editorial team researches licensing exams, medical education and healthcare careers worldwide. Every figure is checked against the official exam body, regulator or statistics office and dated; articles are re-reviewed when rules change. MediFlow is operated by ICSL FZE, SPC Free Zone, Sharjah, UAE, with a branch office: Exchange Tower, Business Bay, Dubai.
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