ABIM Endocrinology key terms

A blood test that reflects average glucose over roughly the prior two to three months by measuring glycated hemoglobin. It is used to diagnose diabetes and to monitor long-term glycemic control.

A state in which tissues respond poorly to insulin, so the pancreas must secrete more to keep glucose normal. It underlies type 2 diabetes and is common in metabolic syndrome and polycystic ovary syndrome.

An acute complication of diabetes with hyperglycemia, ketone accumulation, and metabolic acidosis, often triggered by infection or missed insulin. Treatment requires fluids, insulin, and careful potassium replacement.

A hyperglycemic emergency marked by extreme glucose elevation, high serum osmolality, and severe dehydration without substantial ketosis. It occurs mainly in older adults with type 2 diabetes and carries high mortality.

A peptide released in equal amounts with insulin when proinsulin is cleaved. It reflects endogenous insulin secretion and helps distinguish type 1 from type 2 diabetes and evaluate hypoglycemia.

A drug that mimics glucagon-like peptide-1, increasing glucose-dependent insulin release, slowing gastric emptying, and reducing appetite. It also lowers weight and offers cardiovascular and kidney benefits.

An oral drug that blocks sodium-glucose cotransporter 2 in the kidney, increasing urinary glucose loss. It lowers glucose and weight and reduces heart failure and kidney disease progression.

A screening measure calculated as weight in kilograms divided by height in meters squared. It categorizes weight status but does not directly measure body fat or account for muscle mass.

A cluster of cardiometabolic risk factors including increased waist circumference, elevated triglycerides, low HDL cholesterol, high blood pressure, and elevated fasting glucose. Three or more factors define the syndrome.

The cholesterol carried by low-density lipoprotein particles and a major causal factor in atherosclerotic cardiovascular disease. Lowering it with statins or other agents reduces cardiovascular events.

An inherited disorder, usually autosomal dominant, that causes markedly elevated LDL cholesterol from birth. It leads to premature atherosclerosis and requires early, often combination, lipid-lowering treatment.

A monoclonal antibody that blocks proprotein convertase subtilisin/kexin type 9, increasing LDL receptor recycling and lowering LDL cholesterol. It is used in familial hypercholesterolemia and very high-risk patients.

Weight-loss surgery that alters the stomach, intestine, or both. It produces durable weight loss and improves type 2 diabetes, hypertension, and dyslipidemia more than medical therapy alone.

A pituitary hormone that stimulates thyroid hormone production. Because it rises when thyroid hormone is low, it is the most sensitive first-line test for primary thyroid dysfunction.

The unbound portion of thyroxine in serum, representing hormone available to tissues. It is measured with TSH to classify hypothyroidism and hyperthyroidism and to monitor treatment.

An autoimmune disease in which lymphocytes and antibodies destroy thyroid tissue, usually causing chronic hypothyroidism. It is the most common cause of hypothyroidism in iodine-sufficient regions.

An autoimmune cause of hyperthyroidism in which stimulating antibodies activate the TSH receptor. It may produce a diffuse goiter and extrathyroidal signs such as orbitopathy or pretibial myxedema.

A life-threatening exacerbation of hyperthyroidism with fever, tachycardia, agitation, and multi-organ dysfunction. Treatment includes beta-blockade, a thionamide, iodine, glucocorticoids, and supportive care.

Mild thyroid failure with an elevated TSH and a normal free T4. Treatment is considered when symptoms, pregnancy plans, or cardiovascular risk justify it.

A protein made only by thyroid follicular cells and stored in colloid. After thyroidectomy for differentiated cancer, serum levels help detect residual or recurrent disease.

A pituitary hormone that stimulates the adrenal cortex to produce cortisol and androgens. Its measurement helps distinguish adrenal from pituitary causes of Cushing syndrome and adrenal insufficiency.

A test in which a dose of dexamethasone is given to assess cortisol suppression. Failure to suppress suggests Cushing syndrome; the dose and duration vary by protocol.

Failure of the adrenal cortex to produce cortisol and aldosterone, often from autoimmune destruction. It causes fatigue, hypotension, hyperkalemia, and hyperpigmentation from elevated ACTH.

A condition of sustained excess cortisol from medication, an adrenal tumor, or an ACTH-producing tumor. It causes central obesity, hypertension, hyperglycemia, osteoporosis, and easy bruising.

A benign pituitary adenoma that secretes prolactin. It causes amenorrhea, galactorrhea, and infertility in women and hypogonadism or mass effects in men.

A condition of excessive dilute urine due to deficient vasopressin secretion or impaired kidney response. It causes polyuria, thirst, and hypernatremia if water intake is inadequate.

A syndrome of inappropriate antidiuretic hormone secretion causing dilute hyponatremia with concentrated urine. It occurs with lung disease, central nervous system disorders, and some drugs or cancers.

A common endocrine disorder with irregular ovulation, high androgens, and often insulin resistance. Diagnosis uses Rotterdam criteria and requires excluding other causes of oligo-ovulation or hyperandrogenism.

Low sex hormone production caused by insufficient pituitary gonadotropin release rather than gonadal failure. It causes delayed puberty, amenorrhea, infertility, and low libido; causes include tumors and functional suppression.

Loss of normal ovarian function before age 40, causing amenorrhea, elevated FSH, and infertility. Causes include genetics, autoimmunity, and treatments; hormone therapy is usually needed.

A chromosomal disorder in phenotypic females with loss of part or all of an X chromosome. It causes short stature, gonadal dysgenesis, and cardiovascular and renal anomalies.

A chromosomal disorder in males with an extra X chromosome, usually 47,XXY. It causes small testes, gynecomastia, infertility, and elevated gonadotropins.

Excess coarse, dark terminal hair in women in a male-pattern distribution. It reflects androgen excess from causes such as polycystic ovary syndrome, adrenal disorders, or medications.

A hormone that raises serum calcium by increasing bone resorption, renal calcium reabsorption, and activation of vitamin D. Its measurement helps classify hypercalcemia and hypocalcemia.

Excess parathyroid hormone production from one or more parathyroid glands, causing hypercalcemia. It often presents with kidney stones, osteoporosis, or incidentally; surgery is definitive for many patients.

Low bone mass and disrupted bone microarchitecture that increase fracture risk. It is diagnosed by DXA T-score or a fragility fracture and treated with lifestyle measures and medications.

A bone mineral density result comparing a patient with a young adult reference mean, expressed in standard deviations. A T-score of −2.5 or lower defines osteoporosis.

A fat-soluble vitamin made in skin after sun exposure and obtained from diet. It supports intestinal calcium absorption and bone mineralization; severe deficiency causes osteomalacia and hypocalcemia.

A validated risk calculator that estimates 10-year probability of major osteoporotic fracture and hip fracture. It incorporates bone density and clinical risk factors to guide treatment decisions.

A hormone produced by osteocytes that lowers serum phosphate by reducing renal reabsorption and suppresses vitamin D activation. Excess causes hypophosphatemic rickets or tumor-induced osteomalacia.