PE30.1-7 | Endocrinology — Graded Quiz

The target is rapid normalisation: TSH <5 mIU/L and free T4 in the upper half of the reference range within 2–4 weeks. Levothyroxine 10–15 mcg/kg/day is the standard dose. T3 is not used; the brain converts T4 to T3 locally. Delay causes irreversible intellectual disability.

Congenital hypothyroidism: start levothyroxine 10–15 mcg/kg/day immediately on confirmed diagnosis; normalise TSH within 2–4 weeks. Classic signs: prolonged jaundice, constipation, large fontanelle, lethargy, coarse facial features.

Slow uptitration (B) is inappropriate — the neonatal brain is exquisitely sensitive to hypothyroidism in the first months of life. Delay to 6 weeks (C) is harmful. T3 supplementation (D) is not standard — peripheral conversion of T4 to T3 is sufficient.

A borderline heel-prick TSH at or just above the cut-off (programme-dependent, typically 10–20 mIU/L) must be confirmed by serum TSH + free T4 before treatment is started. The physiological TSH surge at birth dissipates by day 2–3, so a day 3–5 screen should not reflect the surge. Confirmatory serum testing distinguishes true congenital hypothyroidism from a borderline screen.

Interpret neonatal thyroid screening: heel-prick TSH at day 3–5 reflects post-surge baseline. Borderline or elevated TSH → urgent serum TSH + free T4 confirmation before starting levothyroxine. The physiological TSH surge resolves by day 2–3 of life.

Ignoring the borderline result (B) risks missing congenital hypothyroidism. Starting levothyroxine without serum confirmation (C) risks treating a false positive. Repeating heel-prick at 6 weeks (D) is too late to prevent harm if the diagnosis is true.

Paediatric T2DM (obese, acanthosis nigricans, family history, no ketonuria) may be initially managed with lifestyle modification plus metformin (approved ≥10 years). Insulin is added when HbA1c targets are not met or during acute metabolic decompensation. Sulfonylureas are not first-line in paediatric T2DM.

Paediatric T2DM: rising prevalence in Indian adolescents with obesity. First-line = lifestyle modification + metformin (≥10 years). Distinguish from T1DM by obesity, acanthosis nigricans, strong family history, absent/mild ketonuria, and positive C-peptide.

Insulin is not mandatory at onset for T2DM without DKA (A). T1DM and T2DM differ in aetiology, pathophysiology, and initial management (C). Sulfonylureas (D) are not approved or recommended as first-line in paediatric T2DM in Indian/international guidelines.

In DKA, serum K+ may be normal or high despite total-body K+ depletion (due to acidosis-driven shift out of cells). As insulin is given and acidosis corrects, K+ rapidly shifts intracellularly. Add K+ replacement once urination is confirmed and serum K+ is <5.5 mEq/L, targeting K+ 4–5 mEq/L throughout treatment.

DKA potassium management: total body K+ is depleted but serum K+ may be high before insulin. Add K+ replacement to IV fluids once K+ <5.5 mEq/L and urine output is confirmed. Monitor K+ hourly; hypokalaemia after insulin initiation is the commonest electrolyte complication.

Waiting until K+ <3.5 (A) risks dangerous hypokalaemia. Adding K+ in the first bolus (C) risks hyperkalaemia in a patient who may not yet be urinating. Calcium gluconate (D) is for ECG-threatening hyperkalaemia (e.g., renal failure) — in DKA, insulin itself drives K+ down and K+ replacement is needed, not calcium.

46,XX + markedly elevated 17-OHP = congenital adrenal hyperplasia (21-hydroxylase deficiency). The salt-wasting form causes life-threatening hyponatraemia + hyperkalaemia (adrenal crisis). Emergency treatment: IV hydrocortisone 25 mg/m² stat followed by maintenance hydrocortisone + isotonic saline. Fludrocortisone alone is insufficient — glucocorticoid replacement is required first.

CAH (21-hydroxylase deficiency): 46,XX + markedly elevated 17-OHP + salt wasting = adrenal crisis. Emergency: IV hydrocortisone 25 mg/m² stat + isotonic saline. Long-term: hydrocortisone + fludrocortisone + NaCl supplements. Sex assignment only after MDT evaluation.

Fludrocortisone alone (B) corrects mineralocorticoid deficit but does not provide glucocorticoid replacement — hydrocortisone is needed acutely. Sex assignment (C) must await full MDT evaluation — 46,XX karyotype alone is insufficient. 17-OHP is not a marker of hypothyroidism (D).

An autonomous ovarian cyst secreting oestrogen independently of the HPG axis causes peripheral (GnRH-independent) precocious puberty. The LH/FSH responses to GnRH are brisk in this case — which may seem to contradict the peripheral pattern — HOWEVER, the question phrasing highlights that the ultrasound shows an autonomous cyst: the gonadotropin response in peripheral precocious puberty is often SUPPRESSED, but the presence of the cyst with peripheral clinical features directs the diagnosis. The critical distinguishing feature is the autonomous source (cyst) not the HPG axis.

Peripheral (GnRH-independent) precocious puberty: oestrogen/androgen secretion independent of HPG axis (autonomous ovarian cyst, McCune–Albright, congenital adrenal hyperplasia). GnRH stimulation shows suppressed LH/FSH in true peripheral precocious puberty. Autonomous source must be identified and treated.

GnRH-dependent (A) has elevated LH/FSH on stimulation AND shows no autonomous peripheral source. Premature adrenarche (D) causes pubic/axillary hair via adrenal androgen excess, not breast development, and does not cause a 3-year bone age advance or an ovarian cyst. McCune–Albright (C) must not be excluded on café-au-lait absence alone — the classic triad is not always complete.

CDGP (constitutional delay of growth and puberty) is characterised by: delayed bone age, positive family history, normal GnRH stimulation response (LH/FSH rise appropriately), and spontaneous onset of puberty eventually. Isolated hypogonadotropic hypogonadism (Kallmann syndrome) includes anosmia and may show absent/blunted GnRH response.

CDGP vs hypogonadotropic hypogonadism: CDGP has positive family history, delayed bone age, normal GnRH response, and eventual spontaneous puberty. Kallmann syndrome adds anosmia. Check karyotype (Klinefelter 47,XXY), LH/FSH, and thyroid function in all cases of delayed puberty.

Low LH/FSH on stimulation (A) points to hypogonadotropic hypogonadism, not CDGP. Anosmia (C) is the hallmark of Kallmann syndrome. An abnormal MRI (D) indicates an organic cause (pituitary lesion), not constitutional delay.

Children born SGA who fail to show adequate catch-up growth by age 2–4 years have an approved indication for recombinant GH therapy. Approximately 10% of SGA children do not catch up. The low-normal IGF-1 and reduced growth velocity (4 cm/year) in this context support SGA-related short stature. GH stimulation testing may be normal in SGA — the GH axis is structurally intact but relatively GH-resistant.

SGA without catch-up growth by age 4: approved indication for recombinant GH therapy. Approximately 10% of SGA children have persistent short stature. GH stimulation tests may be normal — SGA is a peripheral GH-resistance state, not classical GH deficiency.

GH stimulation testing (A) may be normal in SGA-related short stature — this is not primarily GH deficiency. Reassurance alone (C) misses an approved and effective treatment indication. Familial short stature (D) requires documentation of short parents and normal growth velocity — velocity here is reduced.

Current guidelines (IAP, EAU) recommend orchidopexy at 6–18 months of age to preserve spermatogenesis and reduce malignancy risk. At age 2, spontaneous descent will not occur. A non-palpable testis requires laparoscopy to determine if it is intra-abdominal, atrophic, or absent. Hormonal therapy (hCG/GnRH) has low success rates and is not first-line.

Cryptorchidism: refer for orchidopexy at 6–18 months. Non-palpable testis requires laparoscopy. Bilateral undescended testes in a phenotypic male — investigate for disorders of sexual development (e.g., 46,XX CAH). Malignancy risk persists even after orchidopexy.

Observing until age 5 (A) causes irreversible damage to germinal epithelium — intervention must occur before age 2 ideally. hCG injections (C) have low success (<20%) and are not the standard recommendation in current guidelines. Non-palpable testes (D) carry an increased malignancy risk and must be evaluated laparoscopically.

Crossing weight centiles upward (from 50th to 85th) while height remains stable = increasing BMI. IAP/WHO growth charts: BMI ≥85th centile = overweight; ≥95th = obese. The initial management is lifestyle counselling (diet, physical activity), BMI monitoring every 3 months, and screening for comorbidities. Pharmacotherapy is not first-line.

Paediatric obesity monitoring: use BMI-for-age IAP charts (≥85th = overweight, ≥95th = obese). First-line = structured lifestyle modification. Screen for comorbidities (insulin resistance, hypertension, dyslipidaemia, NAFLD). Pharmacotherapy only for severe obesity with comorbidities in adolescents.

Overweight is not a normal variant requiring no action (A) — it tracks into adult obesity with metabolic complications. Orlistat (C) is not indicated without evidence of obesity-related comorbidities in a primary-prevention school-health context. Ordering investigations (D) before lifestyle advice inverts the management sequence; investigations are for suspected underlying endocrine cause.