Metabolic Bone Diseases Practice Questions

Q: Increased alkaline phosphatase is seen in which of the following conditions?

Paget's disease. **Explanation:** **Paget’s Disease (Correct Answer):** In Paget’s disease (Osteitis Deformans), there is a localized, intense disorder of bone remodeling characterized by excessive osteoclastic resorption followed by a disorganized, compensatory increase in osteoblastic activity. **Alkaline Phosphatase (ALP)** is a marker of osteoblastic activity. Because the bone formation in Paget’s is extremely rapid (albeit disorganized), serum ALP levels are characteristically **markedly elevated**, while serum calcium and phosphate levels typically remain normal. **Why the other options are incorrect:** * **Osteoporosis:** This is a "silent" metabolic bone disease where bone quality and quantity decrease, but the biochemical profile (Calcium, Phosphate, and ALP) remains **normal**. * **Multiple Myeloma:** This is a plasma cell dyscrasia characterized by purely **osteolytic** lesions. Because there is a lack of reactive osteoblastic activity (due to the inhibition of osteoblasts by myeloma cells), the ALP level is typically **normal**, despite extensive bone destruction. * **Osteolytic Metastasis:** While bone destruction occurs, purely osteolytic lesions (e.g., from thyroid or renal cell carcinoma) usually do not significantly elevate ALP. In contrast, **osteoblastic** metastases (e.g., Prostate cancer) would show elevated ALP. **NEET-PG High-Yield Pearls:** * **Paget’s Disease Triad:** Normal Calcium, Normal Phosphate, and Markedly Increased ALP. * **Marker of Bone Resorption:** Urinary Hydroxyproline or N-telopeptide (increased in Paget's). * **Imaging:** Look for "Cotton wool" appearance of the skull or "Picture frame" vertebrae. * **Treatment of Choice:** Bisphosphonates (Zoledronic acid).

Q: In osteomalacia, all the following are seen except?

Increased resistance to pathological fractures. **Explanation:** Osteomalacia is a metabolic bone disease characterized by **defective mineralization** of the organic bone matrix (osteoid), usually due to Vitamin D deficiency. This results in "soft bones," which are structurally weak. **Why Option C is the correct answer:** In osteomalacia, the bone becomes soft and pliable rather than brittle. However, because the mineral content (calcium hydroxyapatite) is significantly reduced, the bone loses its structural integrity. This leads to **decreased resistance** to stress, making the patient highly prone to **pathological fractures** and skeletal deformities (like bowing of legs). Therefore, saying there is "increased resistance" is pathophysiologically incorrect. **Analysis of other options:** * **A. Looser zones:** These are pathognomonic radiolucent lines (pseudofractures) representing stress fractures healed with unmineralized osteoid. Common sites include the axillary border of the scapula, neck of the femur, and pubic rami. * **B. High alkaline phosphatase (ALP):** Osteoblastic activity increases in an attempt to form new bone to compensate for the structural weakness, leading to elevated serum ALP levels. * **D. Diminished urinary excretion of calcium:** Due to Vitamin D deficiency, intestinal calcium absorption is low. The body compensates via secondary hyperparathyroidism, which increases renal tubular reabsorption of calcium, resulting in low urinary calcium levels (Hypocalciuria). **NEET-PG High-Yield Pearls:** * **Biochemical Triad:** Low/Normal Serum Calcium, Low Serum Phosphate, and High ALP. * **Radiology:** "Codfish vertebrae" (biconcave) and "Milkman’s fractures" (Looser zones). * **Histology:** Increased thickness of osteoid seams (Goldner’s Trichrome stain). * **Clinical:** Diffuse bone pain, proximal muscle weakness, and a waddling gait.

Q: Erlenmeyer flask deformity of bones is seen in?

Osteopetrosis. **Explanation:** **Osteopetrosis** (Albers-Schönberg disease/Marble Bone Disease) is the correct answer. The underlying pathology is a **functional defect in osteoclasts**, leading to impaired bone resorption and remodeling. Because the metaphyses of long bones (especially the distal femur and proximal tibia) fail to remodel and narrow during growth, they remain abnormally wide and flared. This radiographic appearance resembles an **Erlenmeyer flask**. **Analysis of Incorrect Options:** * **Achondroplasia:** Characterized by impaired endochondral ossification. Classic radiographic findings include "bullet-shaped" vertebrae, "trident hand," and a "champagne glass" pelvis, but not the Erlenmeyer flask deformity. * **Osteogenesis Imperfecta:** A collagen type 1 defect leading to "brittle bones." Radiographs typically show osteopenia, multiple fractures, and "popcorn calcifications" at the metaphysis, rather than symmetric metaphyseal flaring. * **Paget’s Disease:** Involves excessive, disorganized bone remodeling. Key features include cortical thickening, "picture frame" vertebrae, and "cotton wool" appearance of the skull. **High-Yield Clinical Pearls for NEET-PG:** * **Differential Diagnosis for Erlenmeyer Flask Deformity (Mnemonic: LEAD):** * **L:** Lipid storage diseases (Gaucher’s disease – *Most common cause*) * **E:** Enchondromatosis (Ollier’s disease) * **A:** Anemias (Thalassemia major) * **D:** Dysplasias (Osteopetrosis, Pyle’s disease) * **Osteopetrosis Key Features:** "Bone-within-bone" appearance (Endobone), "Sandwich vertebrae," and pancytopenia due to marrow space obliteration. * **Gaucher’s Disease:** If both Gaucher’s and Osteopetrosis are in the options, Gaucher’s is statistically the most common cause of this deformity, but Osteopetrosis is the classic "textbook" association for metabolic bone exams.

Q: Which bony changes are seen in hyperparathyroidism?

All of the above. **Explanation:** Hyperparathyroidism (HPT), particularly the primary form, leads to an overproduction of Parathyroid Hormone (PTH). PTH increases osteoclastic activity to mobilize calcium from bones into the blood, resulting in a spectrum of skeletal changes collectively known as **Osteitis Fibrosa Cystica**. * **Subperiosteal Bone Resorption:** This is the **most sensitive and pathognomonic** radiographic sign of hyperparathyroidism. It is most commonly seen on the radial aspect of the middle phalanges of the index and middle fingers. * **Brown’s Tumor (Osteoclastoma):** These are non-neoplastic lytic lesions caused by intense localized bone resorption. The "brown" color is due to vascularity, hemorrhage, and hemosiderin deposition within the fibrous tissue. * **Multiple Bone Cysts:** Chronic PTH elevation leads to the replacement of marrow with fibrous tissue and the formation of cystic spaces (Osteitis Fibrosa Cystica), making the bone weak and prone to pathological fractures. **Why "All of the above" is correct:** Since hyperparathyroidism triggers a systemic increase in bone remodeling and resorption, it manifests through all three features: subperiosteal resorption (early sign), bone cysts, and Brown's tumors (late signs). **High-Yield Clinical Pearls for NEET-PG:** * **Salt and Pepper Skull:** A classic radiological appearance caused by multiple tiny lucent areas in the calvarium. * **Rugger Jersey Spine:** Seen in secondary hyperparathyroidism (Renal Osteodystrophy), characterized by bands of sclerosis at the vertebral endplates. * **Looser’s Zones:** These are pseudofractures more characteristic of Osteomalacia, not HPT. * **Biochemical Triad:** Hypercalcemia, Hypophosphatemia, and elevated Serum Alkaline Phosphatase (SAP).

Q: Wormian bones are seen in which of the following conditions?

Osteogenesis imperfecta. **Explanation:** **Wormian bones** (also known as intrasutural bones) are small, accessory bone ossicles found within the sutures of the skull, most commonly in the lambdoid suture. Their presence is a hallmark radiographic sign of certain skeletal dysplasias and metabolic bone diseases. 1. **Why Osteogenesis Imperfecta (OI) is correct:** OI is a genetic disorder of Type I collagen synthesis. The defective collagen leads to delayed ossification of the skull. As a result, multiple small, irregular centers of ossification form within the sutures to fill the gaps, appearing as a "mosaic" or "jigsaw puzzle" pattern on X-rays. In OI, these are often numerous (more than 10) and are a diagnostic criteria. 2. **Why the other options are incorrect:** * **Scheuermann's disease:** This is a condition of juvenile kyphosis caused by wedge-shaped vertebrae and Schmorl’s nodes; it does not involve skull ossification defects. * **Paget's disease:** Characterized by disordered bone remodeling, it shows "Cotton wool spots" on the skull and thickening of the vault, but not Wormian bones. * **Osteoclastoma (Giant Cell Tumor):** A benign but locally aggressive bone tumor typically found in the epiphysis of long bones (e.g., distal femur); it has no association with sutural bones. **High-Yield Clinical Pearls for NEET-PG:** To remember the causes of Wormian bones, use the mnemonic **"PORK CHOP"**: * **P:** Pyknodysostosis (associated with "doll-like" face and osteosclerosis) * **O:** Osteogenesis Imperfecta * **R:** Rickets (healing phase) * **K:** Kinky Hair Syndrome (Menkes disease) * **C:** Cleidocranial Dysplasia (associated with absent clavicles) * **H:** Hypothyroidism / Hypophosphatasia * **O:** One (Trisomy 21 / Down Syndrome) * **P:** Pachydermoperiostosis

Q: A 'petrified man' refers to a condition characterized by extensive calcification and ossification. Which of the following conditions is most likely associated with this description?

Generalized myositis ossificans. ### Explanation **1. Why the Correct Answer is Right:** **Generalized Myositis Ossificans**, also known as **Fibrodysplasia Ossificans Progressiva (FOP)**, is a rare genetic connective tissue disease. It is characterized by the progressive transformation of soft tissues (muscles, tendons, and ligaments) into heterotopic bone. Over time, this extra-skeletal bone formation bridges joints, leading to permanent immobility. The term **'Petrified Man'** is used because the patient’s body literally turns into a "stone-like" state, locking the skeleton into a fixed position. A classic diagnostic hallmark is a congenital malformation of the **great toe (hallux valgus)**. **2. Why the Incorrect Options are Wrong:** * **B. Ehlers-Danlos Syndrome:** This is a disorder of collagen synthesis characterized by joint **hypermobility** and skin hyperextensibility. It is the opposite of "petrification," as patients are excessively flexible ("Rubber Man" syndrome). * **C. Osteogenesis Imperfecta:** Also known as "Brittle Bone Disease," this involves a defect in Type I collagen leading to frequent fractures and blue sclera, not extensive soft tissue calcification. * **D. Cherubism:** This is a rare genetic disorder of the jaws where bone is replaced by painless, cystic fibro-optical lesions, giving the child a "cherubic" (angelic) facial appearance. It does not involve generalized bodily ossification. **3. NEET-PG High-Yield Pearls:** * **Inheritance:** FOP is usually caused by a mutation in the **ACVR1 gene**. * **Pattern of Ossification:** It typically follows a cranio-caudal and axial-to-appendicular pattern (starts at the neck/shoulders and moves down). * **Contraindication:** **Biopsy or surgery** of the lesions is strictly contraindicated as trauma triggers "flare-ups" and accelerates explosive new bone formation. * **Radiology:** Look for "bridging" of the spine and limb joints by ectopic bone.

Q: A 8-year-old boy is being treated for rickets. Which of the following investigations shows the earliest evidence for healing?

Radiological examination of long bones. In Rickets, the hallmark of healing is the mineralization of the previously uncalcified osteoid at the growth plate. **Why Radiological Examination is Correct:** The **earliest** objective evidence of healing in rickets is seen on an X-ray of the wrist or knee. Within **1 to 3 weeks** of starting Vitamin D therapy, a new line of calcification appears at the zone of provisional calcification (the **"Line of Heubner"**). This represents the rapid deposition of calcium salts in the metaphyseal osteoid, making it the most reliable early indicator of a therapeutic response. **Analysis of Incorrect Options:** * **Serum Calcium (A):** Calcium levels often remain near normal in rickets due to secondary hyperparathyroidism. While they may rise slightly during treatment, they are not a specific or earliest indicator of bone healing. * **Serum Phosphates (B):** Phosphate levels rise as the disease resolves, but this biochemical shift precedes the structural repair of the bone and is less definitive than radiological changes. * **Serum Alkaline Phosphatase (D):** ALP is a marker of osteoblastic activity. In rickets, ALP is significantly elevated. During healing, ALP levels actually **remain high or may even transiently increase** before slowly returning to normal over several months. It is the *last* parameter to normalize. **NEET-PG High-Yield Pearls:** * **Earliest sign of healing:** Radiological appearance of the "Line of Heubner." * **Last sign to normalize:** Serum Alkaline Phosphatase (ALP). * **Most sensitive biochemical marker for diagnosis:** Serum ALP. * **Radiological features of active rickets:** Cupping, splaying, and fraying of the metaphysis.

Question 1

Increased alkaline phosphatase is seen in which of the following conditions?

Accepted Answer

Paget's disease

Answer

Osteoporosis

Answer

Multiple myeloma

Answer

Osteolytic metastasis

Question 2

In osteomalacia, all the following are seen except?

Accepted Answer

Increased resistance to pathological fractures

Answer

Looser zones

Answer

High alkaline phosphatase levels

Answer

Diminished urinary excretion of calcium

Question 3

Erlenmeyer flask deformity of bones is seen in?

Accepted Answer

Osteopetrosis

Answer

Achondroplasia

Answer

Osteogenesis Imperfecta

Answer

Paget's disease

Question 4

Amber coloured tooth translucency, blue sclerae, bone fragility, and a history of previous bone fractures are characteristic findings in which condition?

Accepted Answer

Osteogenesis imperfecta

Answer

Osteoporosis

Answer

Osteitis deformans

Answer

Osteitis fibrosa cystica

Question 5

All of the following are known causes of osteoporosis except?

Accepted Answer

Fluorosis

Answer

Hypogonadism

Answer

Hyperthyroidism

Answer

Hyperparathyroidism

Question 6

Which bony changes are seen in hyperparathyroidism?

Accepted Answer

All of the above

Answer

Multiple bone cysts

Answer

Subperiosteal bone resorption

Answer

Brown's tumor

Question 7

Wormian bones are seen in which of the following conditions?

Accepted Answer

Osteogenesis imperfecta

Answer

Scheuermann's disease

Answer

Paget's disease

Answer

Osteoclastoma

Question 8

A 'petrified man' refers to a condition characterized by extensive calcification and ossification. Which of the following conditions is most likely associated with this description?

Accepted Answer

Generalized myositis ossificans

Answer

Ehlers-Danlos syndrome

Answer

Osteogenesis imperfecta

Answer

Cherubism

Question 9

A 8-year-old boy is being treated for rickets. Which of the following investigations shows the earliest evidence for healing?

Accepted Answer

Radiological examination of long bones

Answer

Serum calcium

Answer

Serum phosphates

Answer

Serum alkaline phosphatase

Question 10

A previously asymptomatic 62-year-old woman presents with sudden onset of severe midback pain. X-rays reveal an anterior compression fracture of T10. Other vertebral bodies show decreased mineral density and prominent vertical striations. Which of the following is the most likely diagnosis?

Accepted Answer

Osteoporosis

Answer

Multiple myeloma

Answer

Metastatic breast cancer

Answer

Vitamin D deficiency

Metabolic Bone Diseases — MCQs

Metabolic Bone Diseases — MCQs

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