Endocrine confusion pairs
30 Endocrine topics students commonly mix up on Step 1, each with the fastest separator, a side-by-side comparison, and a free practice question.
- Hyperthyroidism vs PheochromocytomaThyroid excess is sustained metabolic overdrive; pheochromocytoma is episodic catecholamine storm.Video
- DKA vs HHSDKA is ketotic anion-gap acidosis; HHS is hyperosmolar dehydration with absent or mild ketones and little acidosis.Video
- Primary adrenal insufficiency vs Secondary adrenal insufficiencyPrimary has high ACTH and mineralocorticoid loss; secondary has low ACTH and preserved aldosterone.Video
- Central diabetes insipidus vs Nephrogenic diabetes insipidusCentral DI responds to desmopressin with urine concentration; nephrogenic DI stays dilute because the kidney cannot respond.Video
- Septic shock vs Adrenal crisisSepsis is infection-led shock; adrenal crisis is refractory shock plus cortisol-failure clues and steroid history.Video
- Endogenous Cushing syndrome vs Exogenous glucocorticoid effectEndogenous Cushing makes cortisol internally; exogenous steroid use suppresses the axis from outside.Video
- Primary hyperparathyroidism vs Malignancy hypercalcemiaHigh PTH means parathyroid source; low PTH means look for malignancy or another non-PTH cause.Video
- Graves disease vs Subacute thyroiditisGraves actively makes new hormone with high uptake; thyroiditis leaks stored hormone with low uptake.Video
- MEN1 vs MEN2MEN1 is MEN1 gene with the three P tumors; MEN2 is RET with medullary thyroid carcinoma and pheochromocytoma.Video
- Cushing disease vs Cushing syndrome from ectopic or adrenal sourcesDisease means pituitary ACTH; ectopic ACTH is ACTH-high but usually nonsuppressible; adrenal Cushing has high cortisol with suppressed ACTH.
- Conn syndrome vs Cushing syndromeConn is aldosterone: hypertension plus hypokalemic metabolic alkalosis and low renin; Cushing is cortisol: striae, proximal weakness,…
- Primary hyperparathyroidism vs Secondary and tertiary hyperparathyroidismPrimary is PTH-high calcium-high without CKD trigger; secondary is PTH-high because calcium is low/normal; tertiary is autonomous PTH-high…Video
- Autoimmune thyroid disease patterns vs Thyroiditis and fibrosing thyroid patternsGraves makes new hormone with high uptake; Hashimoto destroys toward hypothyroid; subacute thyroiditis leaks hormone with low uptake and…
- Thyroid storm vs Pheochromocytoma or sympathomimetic toxidromeThyroid storm is fever plus decompensated thyrotoxicosis with abnormal thyroid labs; pheo/sympathomimetic is catecholamine excess with…
- Differentiated thyroid carcinoma patterns vs Medullary and anaplastic thyroid carcinoma patternsPapillary is nuclei/psammoma/lymphatics; follicular is capsular-vascular invasion/hematogenous spread; medullary is C…
- Type 1 diabetes mellitus vs Type 2 diabetes mellitusType 1 is autoimmune absolute insulin deficiency with low C-peptide and ketosis; type 2 is insulin resistance with preserved early…Video
- MODY vs Type 2 diabetes and LADAMODY is autosomal dominant young nonobese antibody-negative beta-cell dysfunction; type 2 is resistance; LADA is adult autoimmune diabetes.
- Diabetes insipidus vs Primary polydipsiaDI loses water despite need to conserve it; primary polydipsia drinks excess water and can concentrate when intake is withheld.
- Acromegaly vs GigantismAcromegaly is GH excess after epiphyseal closure with acral enlargement; gigantism is GH excess before closure with linear height growth.
- Prolactinoma vs Pituitary stalk effectProlactinoma makes prolactin very high; stalk effect mildly raises prolactin by blocking dopamine inhibition.
- Sheehan syndrome vs Empty sella syndromeSheehan is postpartum ischemic hypopituitarism with failure to lactate; empty sella is imaging-defined CSF-filled sella with flattened…
- Pituitary apoplexy vs Subarachnoid hemorrhagePituitary apoplexy is thunderclap plus sellar mass, visual/ocular palsy, and hypopituitarism; SAH is thunderclap plus meningeal…
- Addison disease vs Waterhouse-Friderichsen syndromeAddison is chronic primary adrenal failure with hyperpigmentation; Waterhouse-Friderichsen is acute septic adrenal hemorrhage with purpura…
- Salt-wasting CAH vs Hypertensive CAH21 has salt wasting and virilization; 11 has hypertension and virilization; 17 has hypertension with low androgens/sexual infantilism.
- Pheochromocytoma vs NeuroblastomaPheochromocytoma is adult episodic catecholamine hypertension; neuroblastoma is a child with malignant abdominal/sympathetic tumor and…
- Carcinoid syndrome vs PheochromocytomaCarcinoid is serotonin flushing/diarrhea/wheezing with 5-HIAA; pheochromocytoma is catecholamine headache/sweating/palpitations with…
- Hypoparathyroid hypocalcemia vs PTH-resistant or vitamin D-deficient hypocalcemiaHypoparathyroid is PTH-low; pseudohypoparathyroid is PTH-high with high phosphate; vitamin D deficiency is PTH-high with low phosphate.
- Paget disease of bone vs Osteoporosis and osteomalaciaPaget is focal high-turnover disorganized bone with high ALP; osteoporosis is low mass with normal mineral labs; osteomalacia is poor…
- Rickets vs OsteomalaciaRickets is defective mineralization before growth-plate closure; osteomalacia is defective mineralization after growth-plate closure.
- Primary hyperaldosteronism vs Secondary and tertiary hyperaldosteronismPrimary is aldosterone-high renin-low; secondary is aldosterone-high renin-high; tertiary is autonomous aldosterone after long stimulation.