PE30.1-7 | Endocrinology — Glossary

A steroid precursor that accumulates in 21-hydroxylase deficiency; serum level markedly elevated (>10,000 ng/dL) is diagnostic; drawn after 48 hours of age.

Deficiency of the CYP21A2 enzyme in the adrenal cortex, blocking cortisol and aldosterone synthesis while shunting precursors to androgens; the commonest cause of ambiguous genitalia and CAH.

46,XY DSD where testosterone cannot be converted to DHT (the mediator of external virilisation); presents as female-appearing genitalia at birth with virilisation at puberty.

Velvety, hyperpigmented skin thickening at the neck and axillae; a cutaneous marker of hyperinsulinaemia and insulin resistance, associated with Type 2 DM and metabolic syndrome.

Deficiency of thyroid hormone arising after birth, most commonly from autoimmune thyroiditis (Hashimoto) in school-age children; causes growth failure, delayed bone age, weight gain, goitre, and systemic hypothyroid features.

Independent activation of adrenal androgen production (DHEAS) at age 6–8 years, causing pubic and axillary hair; not triggered by LH/FSH; does not indicate true puberty.

External genitalia that cannot be clearly assigned as unambiguously male or female at birth; a disorder of sex development requiring urgent multidisciplinary investigation.

46,XY DSD caused by mutation in the androgen receptor gene; complete AIS presents as phenotypic female with absent uterus and intra-abdominal or inguinal testes.

Metabolic acidosis where the unmeasured anions (ketones in DKA) account for the acid load; calculated as Na – (Cl + HCO3), normal 8–12 mEq/L; elevated in DKA.

Autoantibodies against glutamic acid decarboxylase (GAD65); a serological marker of autoimmune beta-cell destruction; positive in most T1DM patients.

Glycoprotein secreted by Sertoli cells of fetal testes; causes regression of Müllerian structures (uterus, tubes, upper vagina) in 46,XY development; absent in 46,XX.

Autoantibodies against thyroid peroxidase enzyme; positive in Hashimoto's thyroiditis and indicate autoimmune aetiology.

Insulin therapy using a once-daily long-acting (basal) insulin for background control plus rapid-acting (bolus) insulin with each meal to mimic physiological secretion.

Skeletal maturity assessed by wrist X-ray (Greulich-Pyle atlas); delayed in hypothyroidism and advanced in hyperthyroidism and precocious puberty.

Crossing of two or more major centile lines on a growth chart in a downward direction over 12–18 months; a reliable indicator of pathological growth requiring referral regardless of absolute height.

Hypothyroidism due to pituitary (secondary) or hypothalamic (tertiary) dysfunction; TSH is inappropriately low or normal despite low fT4.

Potentially fatal complication of paediatric DKA, characterised by headache, bradycardia, hypertension, and declining consciousness; treated with mannitol or hypertonic saline.

Enlarged clitoris at birth (>1 cm stretched length); a cardinal sign of virilisation in a 46,XX infant with CAH or other androgen excess.

An immune-mediated enteropathy triggered by dietary gluten (wheat, rye, barley) that causes villous atrophy, malabsorption, and in children may present with growth failure as the dominant or only complaint; diagnosed by anti-tTG IgA antibody and duodenal biopsy.

A group of autosomal-recessive disorders of adrenal steroidogenesis; 21-hydroxylase deficiency accounts for >90% of cases; causes virilisation of 46,XX females and adrenal crisis.

Thyroid hormone deficiency present from birth, most commonly due to thyroid dysgenesis or dyshormonogenesis; the commonest preventable cause of intellectual disability.

The most common cause of delayed puberty; a normal variant where puberty onset is later than average; bone age is delayed, LH/FSH are normal, and eventual pubertal development is complete.

Severe neurological and growth impairment caused by maternal iodine deficiency during pregnancy; the most preventable form of intellectual disability globally.

Absence of breast development by age 13 in girls or testicular enlargement by age 14 in boys; most commonly constitutional (CDGP) but may indicate pathological hypogonadism.

Acute metabolic emergency characterised by hyperglycaemia (>200 mg/dL), metabolic acidosis (pH <7.3), and ketonaemia; predominantly a complication of Type 1 DM.

Congenital conditions in which chromosomal, gonadal, or anatomical sex is atypical; preferred modern terminology replacing 'intersex'.

An enzymatic defect in the thyroid hormone synthesis pathway (e.g. thyroid peroxidase mutation) causing CH with goitre.

A distinct entity from short stature defined by weight falling across two or more major centile lines downward over time; weight-for-age or weight-for-height declining is the primary finding, with height affected later in chronic cases.

Short stature explained entirely by parental short stature, with normal growth velocity, bone age equal to chronological age, height within the MPH target range, and no pathological cause.

Blood spot TSH measured from heel-prick sample dried on filter paper; the newborn screening modality; values are different from serum TSH (typically higher by 1.5–2×).

Synthetic mineralocorticoid used in salt-wasting CAH to replace aldosterone deficiency; 0.05–0.2 mg/day orally.

Unbound thyroxine, the biologically active fraction measured in serum; low fT4 + elevated TSH = overt primary hypothyroidism.

A pathological cause of short stature characterised by low growth velocity, delayed bone age, normal body proportions, truncal obesity, and peak GH <10 mU/L on two stimulation tests; responds well to GH replacement therapy.

A provocative test for GH secretion in which a pharmacological stimulus (insulin, clonidine, or glucagon) is given and serial GH levels measured; peak GH <10 mU/L on two separate tests confirms GH deficiency in most Indian protocols.

The growth-regulating hormonal cascade in which hypothalamic GHRH stimulates pituitary GH release, which in turn stimulates hepatic IGF-1 production; IGF-1 drives chondrocyte proliferation at the growth plate.

Synthetic GnRH receptor agonist (e.g. triptorelin, leuprolide) used as first-line treatment for central precocious puberty; continuous stimulation desensitises the receptor, switching off LH/FSH secretion.

Diagnostic test for central precocious puberty: GnRH is administered and LH/FSH measured; peak LH >5 IU/L confirms pubertal activation of the HPG axis (central PP).

Enlargement of the thyroid gland; present in dyshormonogenesis and Hashimoto's thyroiditis but absent in thyroid dysgenesis/aplasia.

Activation of the gonads by LH and FSH; results in testicular enlargement in boys (first pubertal sign) and oestrogen production in girls.

The standard radiographic reference for bone age assessment, comparing a left-hand wrist X-ray against age-specific skeletal maturation templates to estimate bone age independently of chronological age.

The rate of height gain expressed in centimetres per year, calculated from at least two measurements 6–12 months apart; the most sensitive clinical indicator of growth disorders, with <4–5 cm/yr in school-age children being a red flag for pathology.

Autoimmune lymphocytic destruction of the thyroid gland, the most common cause of acquired hypothyroidism in children; associated with anti-TPO and anti-thyroglobulin antibodies.

Glycated haemoglobin A1c; reflects average blood glucose over the previous 2–3 months; used both for DM diagnosis (≥6.5%) and monitoring (target <7.0–7.5% in children).

Hypothalamic-pituitary-thyroid axis; regulates thyroid hormone secretion via TRH → TSH → T3/T4 negative feedback loop.

The glucocorticoid used in CAH treatment (replaces cortisol deficiency) and for stress dosing in adrenal crisis; dosed at 10–15 mg/m2/day in 3 doses for maintenance, higher in crisis.

Primary gonadal failure with elevated LH and FSH (pituitary over-stimulating a failing gonad); causes include Turner syndrome (45,X), Klinefelter syndrome (47,XXY), and gonadal damage from chemotherapy/radiation.

Low LH and FSH with delayed puberty; caused by failure of the hypothalamus or pituitary to activate the HPG axis; causes include Kallmann syndrome, hypopituitarism, malnutrition, and chronic illness.

Benign congenital hypothalamic mass that secretes GnRH, causing central precocious puberty; the most common identified CNS cause of central PP in both sexes.

The Indian Academy of Pediatrics-recommended growth reference charts for Indian children aged 5–18 years, based on Indian population data; WHO charts are used for children under 5 years.

Insulin-like growth factor-1, the principal mediator of GH-driven growth at the growth plate; levels are low in GH deficiency but must be interpreted against bone age-adjusted reference ranges, not chronological age.

Reduced cellular response to insulin, requiring greater insulin secretion to maintain euglycaemia; the pathophysiological basis of Type 2 DM and metabolic syndrome.

International Society for Pediatric and Adolescent Diabetes; publishes global evidence-based clinical practice consensus guidelines for paediatric and adolescent DM management.

Chromosomal analysis of cells showing the number and morphology of chromosomes; essential first investigation in DSD to determine chromosomal sex (46,XX, 46,XY, mosaic).

Presence of ketone bodies (acetoacetate detected by dipstick) in the urine; indicates active lipolysis and ketogenesis; significant at 2+ or more in conjunction with hyperglycaemia.

47,XXY chromosomal disorder in boys; characterised by small testes, tall stature, gynecomastia, and infertility; causes hypergonadotrophic hypogonadism.

Deep, sighing, rapid breathing that is the respiratory compensation for metabolic acidosis in DKA; driven by CO2 elimination to raise pH.

Synthetic thyroxine (T4) used as oral replacement therapy for hypothyroidism; dosed by weight (mcg/kg/day), given on an empty stomach once daily.

Localised subcutaneous fat thickening at insulin injection sites due to repeated injections in the same location; impairs insulin absorption and should be prevented by rotation.

Abnormally large tongue; a classic feature of congenital hypothyroidism due to mucopolysaccharide deposition (myxoedema).

Osmotic agent used in cerebral oedema complicating DKA; given at 0.5–1 g/kg IV to draw water out of brain cells and reduce intracranial pressure.

Sporadic disorder (GNAS activating mutation) causing peripheral precocious puberty, café-au-lait spots (Coast of Maine border), and polyostotic fibrous dysplasia; LH/FSH are suppressed.

A calculation estimating a child's genetic growth potential from parental heights: boys = (F+M+13)/2, girls = (F+M−13)/2 in centimetres; the target range is MPH ± 8.5 cm.

Monogenic diabetes caused by autosomal-dominant single-gene defects in beta-cell function; typically non-ketotic, family history in multiple generations, does not require insulin.

Mid-upper arm circumference; a field measure of acute malnutrition — MUAC <11.5 cm in children 6–59 months defines severe acute malnutrition (SAM) and guides community-based therapeutic feeding programmes.

Specialist team for DSD management comprising paediatric endocrinologist, urologist/surgeon, clinical geneticist, psychologist, and social worker; governs sex assignment and long-term care decisions.

Universal heel-prick blood-spot TSH test performed on day 3–5 of life to detect congenital hypothyroidism before clinical signs appear.

Increased urine output caused by glucose exceeding the renal threshold, drawing water into the tubular lumen; responsible for polyuria, dehydration, and electrolyte loss in DM.

A string of oval beads ranging from 1–25 mL used to measure testicular volume; volume ≥4 mL indicates pubertal gonadal enlargement in boys.

A five-point scale (I–V) grading the degree of virilisation of external genitalia in 46,XX infants with CAH; Grade I = clitoromegaly alone, Grade V = fully male-appearing genitalia.

Onset of pubertal signs before age 8 years in girls and 9 years in boys; classified as GnRH-dependent (central) or GnRH-independent (peripheral) based on HPG axis involvement.

Life-threatening adrenal insufficiency in classic salt-wasting CAH, presenting day 5–15 with vomiting, hyponatraemia, hyperkalaemia, hypoglycaemia, and cardiovascular collapse; treated with IV hydrocortisone and saline.

The Tanner staging system (stages I–V) for documenting pubertal progress via breast/pubic hair development in girls and genital/pubic hair in boys; the universal clinical tool for pubertal assessment.

A calibrated instrument for measuring standing height; essential for accurate growth assessment — tape measures and door-frame marks are not acceptable substitutes for clinical measurement.

Elevated TSH with normal fT4; the thyroid is compensating; most cases in children are monitored rather than immediately treated.

The clinical staging system for pubertal development (Tanner stages 1–5) assessing breast and pubic hair in girls, and genitalia and pubic hair in boys; required in the evaluation of all children with growth deviation to assess pubertal contribution to growth.

The onset of breast development in girls; the first sign of true (central) puberty in girls, occurring at a mean age of 9.5–10 years in India.

Failure of normal thyroid gland development — includes aplasia, hypoplasia, and ectopia (e.g. lingual thyroid) — responsible for ~85% of permanent congenital hypothyroidism.

Pituitary hormone that drives thyroid T3/T4 synthesis; elevated in primary hypothyroidism due to loss of negative feedback from deficient thyroid hormone.

45,X chromosomal disorder in girls; characterised by short stature, streak gonads, primary amenorrhoea, and infertility; causes hypergonadotrophic hypogonadism with high LH/FSH.

Autoimmune destruction of pancreatic beta cells leading to absolute insulin deficiency; the commonest form of diabetes in children; requires lifelong exogenous insulin.

Colorimetric reagent strip test that detects glucose (renal threshold ~180 mg/dL) and acetoacetate ketones in urine; a first-line bedside tool for DM screening and DKA evaluation.

A single perineal opening that serves as a common channel for urethra and vagina, resulting from incomplete separation; seen in CAH with high-grade (Prader III–IV) virilisation.