Thyroid, Steroid, Sex Hormone and Bone Drugs for NEET PG Pharmacology: Levothyroxine (ICMR), Antithyroid Drugs, SERMs, Bisphosphonates

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🎯 Exam priority: High. Expect: levothyroxine starting dose in an elderly cardiac patient, the antithyroid drug in the first trimester, steroid withdrawal, tamoxifen and the endometrium, raloxifene and clots, and how to take alendronate.

CBME mapping: PH 7.3–7.9. Indian protocol: ICMR Hypothyroidism workflow (July 2022).

Hypothyroidism: Levothyroxine (ICMR)

Levothyroxine starting doses by type of hypothyroidism, from the ICMR workflow (2022). Drawn by TrackNation.

• Diagnosis: overt = high TSH with low FT4; subclinical = high TSH with normal FT4. Billewicz score ≥ 6 suggests hypothyroidism. Newborn screening: TSH > 30 mU/L.

• Take it on an empty stomach, 30–60 minutes before breakfast, and at least 4 hours apart from drugs that block its absorption.

• Central hypothyroidism: give hydrocortisone first if there is adrenal insufficiency — thyroxine alone can precipitate an adrenal crisis.

• Never use thyroid hormone for obesity or weight loss (boxed warning).

Hyperthyroidism: Antithyroid Drugs

• Methimazole: life-threatening agranulocytosis (report sore throat or fever at once); in the first trimester it can cause birth defects such as aplasia cutis and craniofacial malformations.

• Propylthiouracil: boxed severe liver injury and liver failure, but it may be the drug of choice during or just before the first trimester.

Corticosteroids

• Adrenal insufficiency: hydrocortisone or cortisone is the first choice.

• Withdrawal: taper gradually; drug-induced adrenal insufficiency can last months after stopping, so restart steroids during any stress in that period.

• Adverse effects: unmasked diabetes, posterior subcapsular cataract, raised eye pressure, osteoporosis, growth suppression in children; no smallpox (live) vaccination while on steroids.

Sex Hormones and Modulators

Bone: Bisphosphonates and Denosumab

• Alendronate: swallow with plain water at least 30 minutes before the first food, drink or medicine of the day, and do not lie down for 30 minutes. Watch for osteonecrosis of the jaw and atypical femur fractures (new thigh or groin pain).

• Denosumab: RANKL inhibitor; boxed severe hypocalcaemia in advanced kidney disease (eGFR < 30).

Traps the Examiner Sets

• Elderly or cardiac patient: levothyroxine 12.5–25 mcg/day, not full dose.

• First trimester: propylthiouracil; methimazole later.

• Fever and sore throat on methimazole: check for agranulocytosis.

• Tamoxifen raises uterine cancer risk; raloxifene raises clot risk.

• Alendronate: upright for 30 minutes, empty stomach.

Memory Hooks & Shortcuts

Shortcuts to lock in this article's numbers and lists. Each one only re-packages facts proven above.

• 🧠 Old heart, Low start (12.5–25) — levothyroxine in the elderly or cardiac

• 🧠 Steroids before Thyroxine in central disease — avoid adrenal crisis

• 🧠 PTU for the Pregnant first Trimester — methimazole causes defects then

• 🧠 Methimazole: Mind the Marrow — agranulocytosis

• 🧠 Tamoxifen Troubles the uTerus — uterine malignancy

• 🧠 Raloxifene Raises clots — VTE

• 🧠 Fosamax: 30-30 rule — 30 minutes before food, 30 minutes upright

Rapid-Revision Cards

• Levothyroxine primary (ICMR)

  1.6–1.8 mcg/kg/day, fasting.

• Levothyroxine elderly/CAD

  12.5–25 mcg/day, +12.5–25 every 3–4 wk.

• Congenital hypothyroidism

  10–15 mcg/kg/day, powdered with breast milk.

• Central hypothyroidism

  1.3 mcg/kg/day after hydrocortisone.

• Target TSH (ICMR)

  Young 1–2.5; middle-aged 1.5–3.

• How to take T4

  Empty stomach, 30–60 min before breakfast; 4 h from binders.

• T4 boxed warning

  Not for obesity/weight loss.

• Methimazole

  Agranulocytosis; 1st-trimester defects (aplasia cutis).

• PTU

  Boxed liver failure; choice in 1st trimester.

• Adrenal insufficiency

  Hydrocortisone or cortisone first.

• Steroid taper

  Gradual; HPA suppression for months.

• Steroid eye

  Posterior subcapsular cataract; raised IOP.

• Steroids and vaccines

  No smallpox/live vaccine.

• Estrogen

  Endometrial cancer (unopposed); not for CVD prevention.

• Raloxifene

  SERM; VTE, stroke death.

• Tamoxifen

  Uterine cancer, stroke, PE.

• Letrozole

  Aromatase inhibitor; HR+ breast cancer.

• Clomiphene

  OHSS; visual flashes.

• DMPA

  Bone loss; ≤ 2 years.

• Alendronate

  Water, 30 min before food, upright 30 min.

• Bisphosphonate risks

  ONJ, atypical femur fracture.

• Denosumab

  RANKL; hypocalcaemia in CKD.

Sources

Facts in this article were checked against these documents.

• Standard Treatment Workflow: Hypothyroidism — Indian Council of Medical Research / Department of Health Research, MoHFW, July 2022

• Prescribing labels: levothyroxine, methimazole, propylthiouracil, prednisone, Solu-Cortef, estradiol, Evista, tamoxifen, Femara, clomiphene, Depo-Provera, Fosamax, Prolia — DailyMed, US National Library of Medicine, current labels, accessed November 2026 (link)

• Competency Based Undergraduate Curriculum, Pharmacology (PH 7.3–7.9) — National Medical Commission, 2024

Test Yourself: Practice Questions

Twenty-four questions in NEET PG style, most of them clinical vignettes.

Practice Questions (NEET PG pattern)

Original questions written in the style of the exam: +4 for a correct answer, −1 for a wrong one. Every answer was checked against the sources listed above. NEET PG papers are not published by NBEMS, so these are not past-paper questions.

Q1. A 35-year-old woman, 60 kg, has overt primary hypothyroidism. ICMR's starting levothyroxine dose is about

• (a) 10–15 mcg/kg/day

• (b) 300 mcg weekly

• (c) 1.6–1.8 mcg/kg/day (about 100 mcg)

• (d) 12.5 mcg/day

Q2. A 72-year-old with angina is diagnosed with hypothyroidism. ICMR advises starting levothyroxine at

• (a) 200 mcg/day

• (b) 12.5–25 mcg/day, increased every 3–4 weeks

• (c) full replacement at once

• (d) only after angioplasty

Q3. A newborn's screening TSH is high and confirmed. ICMR's levothyroxine dose is

• (a) wait until 6 months

• (b) 1.3 mcg/kg/day

• (c) 10–15 mcg/kg/day, powdered, with breast milk

• (d) 25 mcg weekly

Q4. A woman with a pituitary tumour has low FT4 and a low cortisol. Before levothyroxine, ICMR says to

• (a) start hydrocortisone first

• (b) nothing else

• (c) give methimazole

• (d) give radioactive iodine

Q5. A patient takes levothyroxine with breakfast and calcium tablets; TSH stays high. The label advice is to take it

• (a) on an empty stomach 30–60 minutes before breakfast, 4 hours apart from interfering drugs

• (b) twice weekly

• (c) at bedtime with milk

• (d) with iron

Q6. A slimming clinic prescribes levothyroxine to a euthyroid woman for weight loss. The label's boxed warning says

• (a) only with metformin

• (b) only for men

• (c) thyroid hormone must not be used for obesity or weight loss

• (d) this is approved

Q7. A woman with Graves' disease is 6 weeks pregnant. The antithyroid drug of choice now is

• (a) methimazole

• (b) propylthiouracil

• (c) levothyroxine

• (d) radioactive iodine

Q8. A baby born to a mother who took methimazole in the first trimester has aplasia cutis. This is

• (a) a recognised methimazole first-trimester malformation

• (b) a forceps injury

• (c) neonatal lupus

• (d) unrelated

Q9. Three weeks after starting methimazole, a woman has fever and a sore throat. The priority is to

• (a) check a white cell count for agranulocytosis

• (b) add PTU

• (c) double the dose

• (d) start antibiotics only

Q10. Propylthiouracil carries a boxed warning for

• (a) agranulocytosis only

• (b) severe liver injury and liver failure

• (c) QT prolongation

• (d) lactic acidosis

Q11. A man stops prednisone 40 mg abruptly after 3 months and collapses after a minor operation a few weeks later. The cause is

• (a) hyperthyroidism

• (b) allergy

• (c) drug-induced secondary adrenal insufficiency

• (d) hyperkalaemia from surgery alone

Q12. For replacement in primary adrenal insufficiency, the label's first choice is

• (a) dexamethasone

• (b) hydrocortisone or cortisone

• (c) fludrocortisone alone

• (d) prednisone alone

Q13. Long-term oral steroids in an asthmatic cause cloudy vision; the lens change typical of steroids is

• (a) retinal detachment

• (b) anterior polar cataract

• (c) posterior subcapsular cataract

• (d) nuclear sclerosis

Q14. A postmenopausal woman with an intact uterus wants estrogen alone for hot flushes. The boxed warning is

• (a) estrogens increase the risk of endometrial cancer

• (b) estrogens cause hypoglycaemia

• (c) estrogens prevent heart disease

• (d) no risk

Q15. A woman on raloxifene for osteoporosis develops a swollen painful calf. The label's boxed warning covers

• (a) hypercalcaemia

• (b) osteonecrosis of jaw

• (c) venous thromboembolism (and death from stroke)

• (d) agranulocytosis

Q16. A woman taking tamoxifen to reduce breast-cancer risk asks about its serious risks. The label lists

• (a) uterine malignancies (and stroke, pulmonary embolism)

• (b) hypothyroidism

• (c) bone loss only

• (d) ovarian hyperstimulation

Q17. A postmenopausal woman with hormone-receptor-positive early breast cancer is given adjuvant letrozole. Letrozole is

• (a) a GnRH agonist

• (b) a SERM

• (c) an aromatase inhibitor

• (d) a progestin

Q18. A woman on clomiphene for ovulation induction develops abdominal pain and distension, nausea and weight gain. Suspect

• (a) appendicitis

• (b) ovarian hyperstimulation syndrome

• (c) ectopic pregnancy only

• (d) fibroid

Q19. A 17-year-old asks to use Depo-Provera injections for 4 years. The label warns of

• (a) lactic acidosis

• (b) hyperkalaemia

• (c) loss of bone mineral density; not beyond 2 years unless other methods are unsuitable

• (d) endometrial cancer

Q20. A woman starting alendronate asks how to take it. Correct advice:

• (a) with milk at bedtime

• (b) with food to avoid nausea

• (c) lying down to absorb better

• (d) with plain water, 30 minutes before the first food or drink, and stay upright 30 minutes

Q21. After 6 years of alendronate, a woman develops new thigh pain with minimal trauma. Suspect

• (a) muscle strain only

• (b) gout

• (c) an atypical femur fracture

• (d) DVT

Q22. A dialysis patient with osteoporosis is given denosumab. The boxed risk is

• (a) hypercalcaemia

• (b) agranulocytosis

• (c) severe hypocalcaemia

• (d) QT prolongation

Q23. Denosumab works by inhibiting

• (a) aromatase

• (b) osteoclast H+ pump

• (c) RANK ligand (RANKL)

• (d) PTH receptor

Q24. In ICMR's hypothyroidism workflow, a young patient's target TSH on treatment is

• (a) < 0.1 mU/L

• (b) 5–10 mU/L

• (c) 1–2.5 mU/L

• (d) 10–20 mU/L

Active Recall

From memory: give ICMR's levothyroxine starting doses for primary, elderly or cardiac, congenital and central hypothyroidism; compare methimazole and propylthiouracil; list corticosteroid adverse effects and why tapering matters; and give the key warning for estrogen, raloxifene, tamoxifen, letrozole, clomiphene, DMPA, alendronate and denosumab.