Previous year question on calcitonin based on neet pg, usmle, plab and fmge or mci screening exams

Calcitonin is used in all of the following conditions, EXCEPT:

A: Hypervitaminosis DB: Postmenopausal osteoporosisC: Paget's diseaseD: Fanconi syndromeCorrect Ans:DExplanation

The ability of calcitonin to block bone resorption and lower serum calcium makes it a useful drug for the treatment of Paget's disease, hypercalcemia, and osteoporosis.

Fanconi syndrome is a disease of the proximal renal tubules of the kidney in which glucose, amino acids, uric acid, phosphate and bicarbonate are passed into the urine, instead of being reabsorbed. Treatment of children with Fanconi syndrome mainly consists of replacement of substances lost in the urine (mainly fluid and bicarbonate). Calcitonin is not indicated in this disease.

In paget's disease bisphosphonates and calcitonin decrease the elevated biochemical markers of bone turnover, such as plasma alkaline phosphatase activity and urinary excretion of hydroxyproline.

Ref: Bikle D.D. (2012). Chapter 42. Agents that Affect Bone Mineral Homeostasis. In B.G. Katzung, S.B. Masters, A.J. Trevor (Eds), Basic & Clinical Pharmacology, 12e.

Sample Previous Year Question on Calcitonin based on previous Year Questions of NEET PG, USMLE,PLAB,FMGE (MCI Screening). Please visit www.medicoapps.org for more such Quizzes

Which of the following drugs used in osteoporosis acts both by decreasing the resorption of bone as well as inducing new bone formation?

A: TeriparatideB: IbandronateC: Strontium ranelateD: Calcitonin

Correct Ans:CExplanation

Strontium ranelate appears to block differentiation of osteoclasts while promoting their apoptosis, thus inhibiting bone resorption. At the same time, strontium ranelate appears to promote bone formation. Unlike bisphosphonates, denosumab, or teriparatide, this drug increases bone formation markers while inhibiting bone resorption markers.

Calcitonin inhibits osteoclastic bone resorption. Although bone formation is not impaired at first after calcitonin administration, with time both formation and resorption of bone are reduced.

Ref: Bikle D.D. (2012). Chapter 42. Agents that Affect Bone Mineral Homeostasis. In B.G. Katzung, S.B. Masters, A.J. Trevor (Eds), Basic & Clinical Pharmacology, 12e.


A 52 year old woman presents to her physician for a check-up. She is recovering from a wrist fracture after a fall. Dual energy x-ray absorptiometry of the hip had shown her to have osteoporosis. She became menopausal at age 50 and did not begin hormone replacement therapy because of a strong family history of breast cancer. She now fears a future hip fracture and would like to begin a bone loss prevention regime.Which of the following pharmaceutical agents is most appropriate for this patient?

A: Calcitonin nasal sprayB: Oral conjugated estrogenC: RaloxifeneD: TamoxifenCorrect Ans:CExplanationRaloxifene is a selective estrogen receptor modulator that helps prevent osteoporosis by lessening bone resorption and reducing bone turnover. It lowers risk for vertebral fractures by 40% to 50%. It is a bone-preserving alternative for women who prefer to avoid estrogen. Raloxifene does not cause breast pain and may lessen the risk for breast cancer in menopausal women. There is also a favorable effect on LDL and cholesterol.

Calcitonin nasal spray is an osteoclastic bone resorption inhibitor that modestly increases bone mineral density and reduces the incidence of vertebral fracture. Although it is an estrogen alternative for bone preservation, its impact on hip fracture is not known. It is also lacks the anti-breast cancer properties of raloxifene.

Oral conjugated estrogen and transdermal estradiolare not the best choices, as this patient wants to avoid estrogen because of a strong family history of breast cancer. The route of administration of estrogen has been shown to have similar effects on bone preservation, even though the transdermal dosage is generally half that of the oral dosage. Breast cancer risk, however, is slightly increased with the unopposed higher dosage oral estrogen replacement.

Tamoxifen , while indicated in the long-term care of breast cancer patients, is not alone useful for treatment or prevention of osteoporosis. Tamoxifen is an anti-estrogen agent that competes with estrogen for binding sites.

Ref: Shoback D. (2013). Chapter 58. Osteoporosis & Glucocorticoid-Induced Osteoporosis. In J.B. Imboden, D.B. Hellmann, J.H. Stone (Eds), CURRENT Diagnosis & Treatment: Rheumatology, 3e.


A 55-year-old diabetic Raj from Mumbai has a long history of renal failure. He is currently waiting for an organ for transplant and has been on hemodialysis in the interim. If this man develops amyloid deposits around his joints, they are likely to be composed of which of the following substances?

A: Amyloid-associated proteinB: Amyloid light chains

C: Beta2 microglobulinD: Calcitonin precursors


Amyloid deposits appear similar by light and electron microscopy, but actually represent a heterogeneous population of proteins that have a common tertiary structure forming a beta-pleated sheet. Questions about the type of amyloid seen in different disease states are favorites on examinations. Here are two tables to help you out:

Systemic amyloidosis:

Chronic active disease AA amyloid from serum amyloid- associated (SAA) protein from liver (choice A)

Myelomas and related diseases AL amyloid from immunoglobulin light chain (choice B)

Chronic hemodialysis Beta2 microglobulin (related to high plasma levels) (choice C)

Nephropathic hereditary forms (familial Mediterranean fever) AA amyloid from SAA (choice A)

Cardiomyopathic hereditary forms (senile systemic amyloidosis) Prealbumin/transthyretin

Neuropathic hereditary syndromes Prealbumin/transthyretin

Localized amyloidosis:

Senile cardiac amyloidosis Atrial natriuretic peptide-related fibrils

Cerebral amyloid in Alzheimer disease, Down syndrome Cerebral amyloid in Alzheimer disease, Down syndrome

Medullary carcinoma of thyroid Calcitonin precursors (choice D)

Isolated, massive, nodular deposits (skin, lung, urogenital tract) AL from light chains (choice B)




C: Beta2 microglobulinD: Calcitonin precursorsCorrect Ans:CExplanation












Which among the following is not a hormonal tumor marker?

A: β-HCGB: CalcitoninC: CatacholamineD: Neuron specific enolaseCorrect Ans:DExplanation

Elevations in Beta-hCG are also found in patients with choriocarcinoma of the uterus, embryonal carcinomas, polyembryomas, mixed cell tumors, and, less commonly, dysgerminomas. Beta-hCG and human placental lactogen (hPL) are the most useful markers for trophoblastic disease.

Calcitonin plays an important role as a tumor marker in monitoring patients with medullary carcinoma of the thyroid and in the diagnosis of multiple endocrine neoplasia type 2. Urinary and plasma catecholamines epinephrine, norepinephrine, dopamine, vanillylmandelic acid (VMA), homovanillic acid (HVA) are the tumor markers for pheochromocytoma.

NSE is not a hormone. It is an enzyme. It is seen in AML.

Which of the following is not true regarding Medullary Ca thyroid?

A: HereditaryB: Secrets calcitoninC: Hormone dependantD: Amyloid stroma


Medullary thyroid cancer (MTC) originates from the parafollicular cells (C cells), which produce the hormone calcitonin. Approximately 25% of medullary thyroid cancer is genetic in nature, caused by a mutation in the RET proto-oncogene. When it coexists with tumors of the parathyroid gland and medullary component of the adrenal glands (pheochromocytoma) it is called multiple endocrine neoplasia type 2 (MEN2). The majority of C cells are located at the junction of the upper third and lower two thirds of the thyroid gland; hence, this is the most common location of MTC. On FNAC, MTC is characterized by the presence of stromal amyloid and the absence of thyroid follicles.


Hypercalcemia in the setting of squamous cell carcinoma esophagus is mainly due to:

A: Bone metastasisB: Calcitonin excessC: Parathormone excessD: Parathormone related peptide secretionCorrect Ans:DExplanation

Hypercalcemia may occur in the absence of osseous metastases in squamous cell carcinoma esophagus, probably from parathormone-related peptide secreted by tumor cells.

Ref:Harrison,E-18,P-765


A female with frequent history of renal stones presented with severe bone pain. Laboratory findings are indicative of primary hyperparathyroidism which is secondary to parathyroid hyperplasia. Treatment is:

A: Removal of all four glandsB: CalcitoninC: Removal of all glands leaving 50 mg of tissue as remnantD: Enlarged glands to be removed


Primary parathyroid hyperplasia involves all of the parathyroid glands. Microscopically, there are two types: chief cell hyperplasia and water-clear cell (wasserhelle) hyperplasia. Hyperplastic glands vary considerably in size but are usually larger than normal (65 mg). When all parathyroid glands are hyperplastic, the gland should be subtotally resected, leaving a 50 mg remnant, and confirmed histologically before removal of the remaining glands. The upper thymus and perithymic tract should be removed in patients with hyperplasia, because a fifth parathyroid gland is present in 15% of cases.

Ref: Doherty G.M. (2010). Chapter 16. Thyroid & Parathyroid. In G.M. Doherty (Ed), CURRENT Diagnosis & Treatment: Surgery, 13e.


Intranasal calcitonin is given for a 65 year old post-menopausal lady. What is the likely indication?

A: Paget's diseaseB: OsteoporosisC: HypercalcemiaD: Osteopetrosis

Correct Ans:BExplanation

Calcitonin-salmon is a hormone that decreases osteoclast activity, thereby impeding postmenopausal bone loss. It is indicated for the treatment of women who are more than 5 years post menopause and have low bone mass relative to healthy premenopausal women. It is available as an injection and as an intranasal spray. The intranasal spray is delivered as a single daily spray that provides 200 IU of the drug.


Which of the following serum tumor marker is used for diagnosis of trophoblastic tumour?

A: a HCGB: CalcitoninC: b HCGD: g HCGCorrect Ans:CExplanation

Most GTN cases are clinically diagnosed, using -hCG evidence of persistent trophoblastic tissue.

Criteria for the Diagnosis of Gestational Trophoblastic Neoplasia:

Plateau of beta-hCG lasts for four measurements over a period of 3 weeks or longer (days 1, 7, 14, and 21).

Rise of beta-hCG of 3 weekly consecutive measurements or longer, over a period of 2 weeks or more (days 1, 7, and 14).

beta-hCG remains elevated for 6 months or more. Histologic diagnosis of choriocarcinoma.

Ref: Hoffman B.L., Schorge J.O., Schaffer J.I., Halvorson L.M., Bradshaw K.D., Cunningham F.G., Calver L.E. (2012). Chapter 37. Gestational Trophoblastic Disease. In B.L. Hoffman, J.O. Schorge, J.I. Schaffer, L.M. Halvorson, K.D. Bradshaw, F.G. Cunningham, L.E. Calver (Eds), Williams Gynecology, 2e.


Which of the following hormone is synthesized from the amino acid Tyrosine?

A: CalcitriolB: CalcitoninC: ThyroxinD: Cortisol


The thyroid hormones triiodothyronine (T3) and thyroxine (T4) in the colloid of the thyroid also are derived from tyrosine.

In dopaminergic cells in the brain, tyrosine is converted to levodopa by the enzyme tyrosine hydroxylase (TH). Tyrosine is also the precursor to the pigment melanin.


Which of the following enzymes stimulate the production of cAMP?

A: AcetylcholineB: Angiotensin IIC: SomatostatinD: Calcitonin

Correct Ans:DExplanation

Cyclic AMP was the first intracellular second messenger signal identified in mammalian cells.

Different peptide hormones can either stimulate (s) or inhibit (i) the production of cAMP from adenylyl cyclase, which is encoded by at least nine different genes.

Hormones that Inhibit Adenylyl Cyclase (HI) and the production of cAMP:AcetylcholineAlpha 2-AdrenergicsAngiotensin IISomatostatin

Hormones that stimulate Adenylyl Cyclase (HI) and the production of cAMP:AcetylcholineADHBeta -AdrenergicsCalcitoninCRHFSHGlucagonhCGLHLPHMSHPTHTSH

Ref: Weil P. (2011). Chapter 42. Hormone Action & Signal Transduction. In D.A. Bender, K.M. Botham, P.A. Weil, P.J. Kennelly, R.K. Murray, V.W. Rodwell (Eds), Harper's Illustrated Biochemistry, 29e.


Which of the following describes humoral hypercalcemia of malignancy (HHM)?

A: The rise in calcium levels due to PTH-rPB: Paraneoplastic Calcitonin Production

C: Vitamin D HypervitaminosisD: Parafollicular C-cell proliferation of Thyroid GlandCorrect Ans:AExplanationThe rise in calcium levels due to PTH-rP is termed humoral hypercalcemia of malignancy (HHM).

A common consequence of some cancers can be increased levels of calcium (hypercalcemia) with secretion of PTH-related peptide (PTH-rP). PTH-rP has significant homology with PTH, but only in the amino-terminal 13 amino acids, which make up the receptor-binding region. Because PTH-rP is not secreted by the parathyroid glands, hypercalcemia produces no feedback regulation of its production. Cancers usually associated with HHM include breast and lung cancers and multiple myeloma.

Ref: Kerr J. (2012). Chapter 13. Connective Tissue and Bone. In L.W. Janson, M.E. Tischler (Eds), The Big Picture: Medical Biochemistry.


All of the following are placental hormones, EXCEPT:

A: Chorionic gonadotropinB: Chorionic thyrotropinC: Chorionic corticotropinD: Chorionic calcitonin


Many hormones are secreted by the syncytiotrophoblast of the chorion, and a few additional hormones are produced by the decidual cells. Placental hormones include,

Chorionic gonadotropin Chorionic thyrotropin

Chorionic corticotropin

Estrogens

Progesterone

Prolactin

Placental lactogen

Ref: Paulsen D.F. (2010). Chapter 23. Female Reproductive System. In D.F. Paulsen (Ed), Histology & Cell Biology: Examination & Board Review, 5e.


Regarding: Calcitonin

Assertion: Calcitonin is a hypocalcemic hormone

Reason: It leads to inhibition of osteoclast-mediated bone resorption

A: Both Assertion and Reason are true, and Reason is the correct explanation for Assertion

B:Both Assertion and Reason are true, and Reason is not the correct explanation for Assertion

C: Assertion is true, but Reason is falseD: Assertion is false, but Reason is trueCorrect Ans:AExplanation

Calcitonin is a hypocalcemic peptide hormone that in several mammalian species acts as an antagonist to PTH. The hypocalcemic activity of calcitonin is accounted for primarily by inhibition of osteoclast-mediated bone resorption and secondarily by stimulation of renal calcium clearance.

Reference:Harrisons Principles of Internal Medicine, 18th Edition, Page 3099


Thyroid medullary cells that produce calcitonin develop from:

A: Ultimobranchial bodyB: Floor of the primitive pharynxC: 3rd pharyngeal archD: Lung buds

Correct Ans:AExplanation

Neural crest derivatives from the ultimobranchial body give rise to thyroid medullary C cells.It produces calcitonin. The C cells are interspersed throughout the thyroid gland.

ALSO KNOWThe ultimobranchial body arises from bilateral ventral swellings of the 4th pharyngeal pouches and gets integrated into the thyroid where it forms the parafollicular cells or C-cells for the production of calcitonin.

Ref: Harrison, E-18, P-2911.


A 54 year old man is admitted to the hospital with cough and dyspnea, which over a period of years has led to marked respiratory embarrassment and cyanosis. Chest x-ray film of the lungs showed bilateral lower lobe ground-glass infiltrates. Wedge biopsy of the lung demonstrates air spaces filled with macrophages containing lipid, periodic acid-Schiff (PAS)-positive granules, and lamellar bodies. There is an accompanying interstitial pneumonitis, hyperplasia of the septal lining epithelial cells, and desquamation of epithelial cells into alveolar. The lamellar bodies within the macrophages are composed of which of the following?

A: AmyloidB: CalcitoninC: FibrinD: SurfactantCorrect Ans:DExplanationThe disease is desquamative interstitial pneumonitis (DIP), which is an idiopathic process related to idiopathic interstitial fibrosis. DIP may respond to steroid therapy but may also progress to end-stage lung disease. The lamellar (layered) bodies within macrophages contain surfactant derived from type II pneumocytes.

Amyloid is deposited extracellularly and is not part of the DIP process. Calcitonin is found in medullary carcinoma of the thyroid.

Fibrin deposition can be part of the DIP process, but occurs as eosinophilic extracellular deposits, rather than as intracellular lamellar bodies.

Ref: Levitzky M.G. (2013). Chapter 2. Mechanics of Breathing. In M.G. Levitzky (Ed), Pulmonary Physiology, 8e.


Osteoclasts are inhibited by:

A: Parathyroid hormoneB: CalcitoninC: 1,25-dihydroxycholecalciferolD: Tumor necrosis factor


Calcitonin inhibits bone resorption by direct action on osteoclasts.

Ref: Ganong’s Review of Medical Physiology, 21st Edition, Page 397


Hypercalcemia associated with malignancy is most often mediated by:

A: Parathyroid hormone (PTH)B: Parathyroid hormone related protein (PTHrP)C: Interleukin - 6 (EL-6)D: Calcitonin


These are several humoral causes of hypercalcemia of malignancy, but is most often associated with over production of PTHrP.

Ref: Harrison’s Principles of Internal Medicine, 16th Edition, page 566


Calcitonin is secreted by:

A: Thyroid glandB: Parathyroid glandC: Adrenal glandsD: Ovaries


Calcitonin is primarily secreted by the parafollicular C cells of the Thyroid gland. It is a hormone secreted in response to elevated blood calcium. It stimulates calcium deposition in bone and calcium excretion by the kidneys, thus reducing blood calcium.

Ref: Essentials of Pharmacology By K D Tripathi, 5th, Edition, Page 301; Ganong's Review of Medical Physiology, 22nd Edition, Page 393.


A patient is on low calcium diet for 8 weeks. Level of which of the following increases to maintain serum calcium levels?

A: PTHB: CalcitoninC: Active 24, 25 dihydroxy cholecalciferolD: Serum phosphate level


The primary function of PTH is to maintain the extracellular fluid (ECF) calcium concentration within a narrow normal range. The hormone acts directly on bone and kidney and indirectly on the intestine through its effects on synthesis of 1,25(OH)2D to increase serum calcium concentrations; in turn, PTH production is closely regulated by the concentration of serum ionized calcium. Any tendency toward hypocalcemia, as might be induced by calcium-deficient diets, is counteracted by an increased secretion of PTH.

This in turn (1) increases the rate of dissolution of bone mineral, thereby increasing the flow of calcium from bone into blood; (2) reduces the renal clearance of calcium, returning more of the calcium filtered at the glomerulus into ECF; and (3) increases the efficiency of calcium absorption in the intestine by stimulating the production of 1,25(OH)2D.

Ref: Potts, J.T., Jüppner H. (2012). Chapter 353. Disorders of the Parathyroid Gland and Calcium Homeostasis. In D.L. Longo, A.S. Fauci, D.L. Kasper, S.L. Hauser, J.L. Jameson, J. Loscalzo (Eds), Harrison's Principles of Internal Medicine, 18e


A 40-year-old developed pathological fractures and was found to be having low bone density after a Dexa Scan. Laboratory tests show low plasma calcium, elevated PTH levels, and low vitamin D levels. The patient is on a balanced diet. However, the patient's plasma creatinine and urea are elevated markedly. Which of the following is the most likely reason for the hypocalcemia and reduced bone mass?

A: Excessive urinary excretion of calciumB: Impaired secretion of calcitoninC: A parathyroid gland tumor generating excessive amounts of PTHD: Reduced renal activity of 1 alpha-hydroxylase activity


Here there are signs of early renal failure. This reduces the levels of 1 alpha-hydroxylase in the proximal tubule cells, thereby reducing the conversion of 25-hydroxyvitamin D, the inactive form of vitamin D, to 1,25-dihydroxyvitamin D, the most active form.

The 25-hydroxycholecalciferol is converted in the cells of the proximal tubules of the kidneys to the more active metabolite 1,25-dihydroxycholecalciferol, which is also called calcitriol or 1,25-(OH)2D3. 1,25-Dihydroxycholecalciferol is also made in the placenta, in keratinocytes in the skin, and in macrophages.

Ref: Barrett K.E., Barman S.M., Boitano S., Brooks H.L. (2012). Chapter 21. Hormonal Control of Calcium & Phosphate Metabolism & the Physiology of Bone. In K.E. Barrett, S.M. Barman, S. Boitano, H.L. Brooks (Eds), Ganong's Review of Medical Physiology, 24e.


Which of the gland secretes calcitonin for regulation of calcium metabolism?

A: Thyroid glandB: Parathyroid glandC: Both of the aboveD: None of the aboveCorrect Ans:AExplanationCalcitonin is produced by the parafollicular cells of the thyroid gland, which are also known as the clear or C cells. Its secretion is increased when the thyroid gland is exposed to a plasma calcium level of approximately 9.5 mg/dL. The actions of calcitonin are short-lived because it has a half-life of less than 10 min in humans.



What is the physiological role of calcitonin in metabolism?

A: Lowers Ca2+ levelsB: Increases Ca2+ levelsC: Increases PO4 levelsD: None of the above

Correct Ans:AExplanationCalcitonin lowers circulating calcium and phosphate levels. It exerts its calcium-lowering effect by inhibiting bone resorption. This action is direct, and calcitonin inhibits the activity of osteoclasts in vitro. It also increases Ca2+ excretion in the urine.



A 42 year old female presented with tingling sensation around her mouth. Trousseau's sign and Chvostek's sign are positive. Which of the following hormone in excess can give rise to this clinical picture?

A: ThyroxineB: CalcitoninC: Parathyroid hormoneD: Cholecalciferol

Correct Ans:BExplanationModerate to severe hypocalcemia is associated with paresthesias, usually of the fingers, toes, and circumoral regions, and is caused by increased neuromuscular irritability. Calcitonin lowers circulating calcium and phosphate

levels. It exerts its calcium-lowering effect by inhibiting bone resorption. This action is direct, and calcitonin inhibits the activity of osteoclasts. It also increases Ca2+ excretion in the urine.

Severe hypocalcemia can induce seizures, carpopedal spasm, bronchospasm, laryngospasm, and prolongation of the QT interval.

Also know:

Chvostek's sign: Twitching of the circumoral muscles in response to gentle tapping of the facial nerve just anterior to the ear.

Trousseau's sign: Carpal spasm which is induced by inflation of a blood pressure cuff to 20 mmHg above the patient's systolic blood pressure for 3 min.



Previous year question on calcitonin based on neet pg, usmle, plab and fmge or mci screening exams

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Transcript of Previous year question on calcitonin based on neet pg, usmle, plab and fmge or mci screening exams