Metabolic Bone Diseases Practice Questions

Q: What is the most common manifestation of osteoporosis?

Compression fracture of the spine. **Explanation:** Osteoporosis is a "silent disease" characterized by reduced bone mass and micro-architectural deterioration, leading to increased bone fragility [1]. **Why Option A is Correct:** The most common clinical manifestation of osteoporosis is a **vertebral compression fracture** [2]. These fractures often occur with minimal trauma or even during routine activities like bending or lifting. While many are asymptomatic and discovered on routine imaging, they frequently present as acute back pain, loss of height, or progressive kyphosis (Dowager’s hump). The mid-to-lower thoracic and upper lumbar spine are the most common sites [2]. **Why Other Options are Incorrect:** * **Option B:** Osteoporosis is typically **asymptomatic** until a fracture occurs. However, serum calcium, phosphate, and alkaline phosphatase levels are characteristically **normal** in primary osteoporosis. Low serum calcium suggests other metabolic bone diseases like Osteomalacia [3]. * **Option C:** Bowing of legs is a classic feature of **Rickets** (in children) or **Osteomalacia/Paget’s disease** (in adults), where the bone matrix is soft or poorly mineralized, unlike osteoporosis where the matrix is normal but decreased in quantity [3]. * **Option D:** Loss of weight is not a feature of osteoporosis. However, **loss of height** is a significant clinical sign due to vertebral collapse. **High-Yield Clinical Pearls for NEET-PG:** * **Gold Standard Diagnosis:** Dual-energy X-ray absorptiometry (DEXA) scan. Osteoporosis is defined as a **T-score ≤ -2.5**. * **Most Common Site of Fracture:** Vertebrae (Compression fracture) [2]. * **Most Common Site of Fracture requiring Hospitalization:** Hip (Femur neck) [2]. * **First-line Treatment:** Bisphosphonates (e.g., Alendronate). * **Screening:** Recommended for all women ≥65 years and men ≥70 years.

Q: Albers-Schönberg disease is defined as which of the following conditions?

Osteopetrosis. **Explanation:** **Albers-Schönberg disease** is the eponym for **Osteopetrosis** (specifically the autosomal dominant, late-onset type). The underlying pathophysiology involves **defective osteoclast function** or recruitment, leading to failure of normal bone resorption. This results in excessively dense, thick, but brittle bones—often described as "marble bone disease." **Why the other options are incorrect:** * **Osteoporosis:** This is a metabolic condition characterized by low bone mass and micro-architectural deterioration, leading to increased fragility. It is the opposite of osteopetrosis in terms of bone density. * **Osteochondritis:** This refers to a group of disorders that affect the growing skeleton, resulting from abnormal growth, injury, or overuse of the developing growth plate and surrounding ossification centers (e.g., Perthes disease). * **Osteomalacia:** This is characterized by inadequate mineralization of the bone osteoid, usually due to Vitamin D deficiency or phosphate depletion. **High-Yield Clinical Pearls for NEET-PG:** * **Radiological Hallmark:** "Bone within a bone" appearance and **"Erlenmeyer flask deformity"** (metaphyseal flaring). * **Sandwich Vertebrae:** Increased density at the superior and inferior endplates of the vertebrae. * **Clinical Complications:** Despite increased density, bones are prone to fractures. Encroachment on the medullary canal leads to **pancytopenia** (myelophthisic anemia) and cranial nerve palsies (due to narrowing of neural foramina). * **Rugger-Jersey Spine:** While classically associated with renal osteodystrophy, a similar appearance can be seen in osteopetrosis.

Q: Paget's disease of bone can develop into which of the following malignancies after 10 years?

Osteosarcoma. **Explanation:** **Paget’s Disease of Bone (Osteitis Deformans)** is characterized by disordered bone remodeling, where excessive bone resorption is followed by disorganized bone formation. This results in a "mosaic pattern" of lamellar bone. **Why Osteosarcoma is the correct answer:** The most dreaded complication of long-standing Paget’s disease is malignant transformation, occurring in approximately **1%** of patients. This is known as **Pagetoid Sarcoma**. Among these, **Osteosarcoma** is the most common histological subtype (followed by fibrosarcoma and chondrosarcoma). The rapid turnover of bone cells and the microenvironment of Pagetoid bone increase the risk of genetic mutations leading to malignancy. Clinically, it is suspected when a patient with stable Paget’s disease develops a sudden increase in pain, a new soft tissue mass, or a pathological fracture. **Why other options are incorrect:** * **Fibrous cortical defect:** This is a benign, asymptomatic, non-neoplastic bone lesion commonly found in children; it is not a malignant transformation. * **Osteoid osteoma:** This is a benign osteoblastic tumor characterized by a "nidus" and nocturnal pain relieved by NSAIDs. It does not arise from Paget’s disease. * **Ankylosing spondylitis:** This is a chronic inflammatory seronegative spondyloarthropathy, not a malignancy. **High-Yield Clinical Pearls for NEET-PG:** * **Secondary Osteosarcoma:** In elderly patients, the most common cause of osteosarcoma is Paget’s disease (unlike primary osteosarcoma, which peaks in the second decade). * **Radiological Sign:** Look for the "Blade of Grass" or "Flame sign" (lytic phase) and "Picture frame vertebra." * **Biochemical Marker:** Markedly elevated **Serum Alkaline Phosphatase (ALP)** with normal Calcium and Phosphate levels. * **Treatment of choice for Paget's:** Bisphosphonates (Zoledronic acid).

Q: Looser's zone occurs in all of the following conditions except?

Hypoparathyroidism. **Explanation:** **Looser’s zones** (also known as pseudofractures, Milkman’s fractures, or Umbauzonen) are narrow radiolucent lines that represent cortical stress fractures replaced by unmineralized osteoid. They typically occur perpendicular to the bone cortex in weight-bearing areas (e.g., femoral neck, axillary border of the scapula, pubic rami). **Why Hypoparathyroidism is the correct answer:** Looser’s zones are a hallmark of conditions characterized by **excessive osteoid** or **increased bone turnover** where mineralization is defective. In **Hypoparathyroidism**, there is a deficiency of Parathyroid Hormone (PTH), leading to low bone turnover and increased bone density (osteosclerosis). Since there is no excess of unmineralized osteoid, Looser’s zones do not occur. **Analysis of incorrect options:** * **Osteomalacia:** This is the most common cause. Defective mineralization leads to the accumulation of soft osteoid at sites of mechanical stress. * **Paget’s disease:** Characterized by high bone turnover and disorganized remodeling. Pseudofractures can occur on the convex side of deformed long bones. * **Fibrous dysplasia:** A condition where normal bone is replaced by fibrous tissue and immature bone, creating structural weaknesses that predispose to pseudofractures. **NEET-PG High-Yield Pearls:** * **Common sites for Looser’s zones:** Axillary border of the scapula (most classic), neck of the femur, ribs, and pubic rami. * **Other conditions associated:** Rickets, Renal Osteodystrophy, and Osteogenesis Imperfecta. * **Radiological appearance:** Transverse lucent bands with sclerotic margins, often bilateral and symmetrical. * **Biochemical marker:** In Osteomalacia (the primary cause), expect **Low/Normal Calcium, Low Phosphate, and High Alkaline Phosphatase (ALP).**

Q: In osteoporosis, what is observed?

Decrease in absolute amount of bone mass. **Explanation:** **1. Why Option A is Correct:** Osteoporosis is defined as a metabolic bone disease characterized by a **decrease in the absolute amount of bone mass** (low bone mineral density). Crucially, while the quantity of bone is reduced, the **chemical composition** of the remaining bone matrix remains normal (normal mineralization). This distinguishes it from Osteomalacia, where the mineral-to-matrix ratio is decreased. **2. Analysis of Incorrect Options:** * **Option B:** Osteoporosis is significantly **more common in females**, particularly post-menopausal women, due to the cessation of the protective effect of estrogen on bone resorption. * **Option C:** Radiographs do **not** show normal bone density. However, they are insensitive for early diagnosis because osteopenia only becomes visible on X-ray after **30-50% of bone mass is lost**. The gold standard for diagnosis is the DEXA scan (T-score ≤ -2.5). * **Option D:** While Hormone Replacement Therapy (HRT) was historically used for prevention, it is **not the primary observation or definition** of the disease. Furthermore, due to risks of breast cancer and thromboembolism, Bisphosphonates (like Alendronate) are now the first-line pharmacological treatment. **High-Yield Clinical Pearls for NEET-PG:** * **Biochemical Profile:** In primary osteoporosis, Serum Calcium, Phosphate, and Alkaline Phosphatase are typically **Normal**. * **Most Common Fracture:** The most common site for an osteoporotic fracture is the **Vertebral body** (compression fracture), followed by the neck of the femur and Colles’ fracture. * **Ward’s Triangle:** An area of low bone density in the neck of the femur, which is one of the earliest signs of osteoporosis on X-ray. * **Singh’s Index:** Used to grade the severity of osteoporosis based on the disappearance of trabecular patterns in the proximal femur.

Q: Which of the following characteristics are TRUE or FALSE about osteopetrosis in a child? 1. Growth retardation 2. Mental retardation 3. Multiple fractures 4. Cataract 5. Hepatosplenomegaly

1, 3, 5 True & 2, 4 False. **Explanation:** **Osteopetrosis** (Albers-Schönberg disease or Marble Bone Disease) is a rare genetic disorder characterized by **defective osteoclast function**. This leads to a failure of bone resorption, resulting in excessively dense but brittle bones. **Why Option A is correct:** 1. **Growth Retardation (True):** Defective remodeling of the primary spongiosa into lamellar bone interferes with longitudinal growth, leading to short stature. 2. **Mental Retardation (False):** Intelligence is typically **normal** in osteopetrosis. Neurological deficits are usually mechanical (e.g., cranial nerve compression due to bony overgrowth of foramina), not cognitive. 3. **Multiple Fractures (True):** Despite increased bone density on X-ray ("chalky bones"), the lack of a proper trabecular pattern makes the bones extremely brittle and prone to pathological fractures. 4. **Cataract (False):** Cataracts are not a feature of this disease. However, **optic atrophy** and blindness are common due to compression of the optic nerve in the optic canal. 5. **Hepatosplenomegaly (True):** As the marrow cavity is obliterated by dense bone, the body resorts to **extramedullary hematopoiesis** in the liver and spleen to compensate for life-threatening anemia and thrombocytopenia. **High-Yield NEET-PG Pearls:** * **Radiological Signs:** "Bone-within-a-bone" appearance, "Sandwich vertebrae" (Rugger-Jersey spine), and "Erlenmeyer flask deformity" of the distal femur. * **Complications:** Pancytopenia (leading to infections and bleeding), cranial nerve palsies (II, VII, and VIII), and osteomyelitis (especially of the mandible). * **Treatment:** Bone marrow transplant is the mainstay for the infantile (malignant) form to provide functional osteoclasts.

Q: Osteoporosis is caused by all of the following, except?

Oestradiol. **Explanation:** **Concept:** Osteoporosis is characterized by a reduction in bone mass (low bone mineral density) due to an imbalance between bone resorption (osteoclasts) and bone formation (osteoblasts). **Why Oestradiol is the correct answer:** Oestradiol (Estrogen) is **bone-protective**. It inhibits bone resorption by inducing apoptosis of osteoclasts and suppressing pro-inflammatory cytokines (like IL-1, IL-6, and TNF-α) that stimulate osteoclastogenesis. A deficiency in oestradiol (as seen in menopause) is the primary cause of **Type I (Postmenopausal) Osteoporosis**. Therefore, oestradiol prevents rather than causes osteoporosis. **Why the other options are incorrect:** * **Corticosteroids:** These are the most common cause of drug-induced osteoporosis. They decrease osteoblast activity, reduce intestinal calcium absorption, and increase renal calcium excretion. * **Methotrexate:** This cytotoxic drug interferes with osteoblast proliferation and increases osteoclast activity, leading to "methotrexate osteopathy" at high or chronic doses. * **Chronic Heparin Therapy:** Long-term heparin use (usually >6 months) stimulates osteoclasts and inhibits osteoblasts, leading to decreased bone density. **High-Yield Clinical Pearls for NEET-PG:** * **Gold Standard Diagnosis:** DEXA Scan (Dual-energy X-ray Absorptiometry). Osteoporosis is defined as a **T-score ≤ -2.5**. * **Most common site of fracture:** Vertebral body (compression fracture), followed by the neck of the femur. * **Drug of Choice:** Bisphosphonates (e.g., Alendronate) are the first-line treatment. They act by inhibiting osteoclast-mediated bone resorption. * **Teriparatide:** A recombinant PTH analogue; it is the only **anabolic** agent (builds new bone) used in severe osteoporosis.

Q: Blue sclera is a characteristic feature of which condition?

Osteogenesis imperfecta. **Explanation:** **Osteogenesis Imperfecta (OI)**, also known as "Brittle Bone Disease," is the correct answer. It is a genetic disorder primarily caused by mutations in the **COL1A1 and COL1A2 genes**, leading to a defect in the synthesis of **Type I Collagen**. **Why Blue Sclera occurs:** The sclera is normally composed of Type I collagen. In OI, the collagen is either deficient or defective, causing the scleral coat to become abnormally thin. This thinness allows the underlying **choroidal veins** to show through, giving the eyes a characteristic blue or slate-gray appearance. **Analysis of Incorrect Options:** * **Osteopetrosis (Marble Bone Disease):** Characterized by defective osteoclast function leading to excessively dense, brittle bones. It does not involve collagen defects of the sclera. * **Cleidocranial Dysostosis:** A RUNX2 gene mutation affecting intramembranous ossification. Key features include absent/hypoplastic clavicles and delayed closure of fontanelles, but not blue sclera. * **Achondroplasia:** The most common cause of dwarfism, caused by a mutation in the **FGFR3 gene**. It affects endochondral ossification; scleral color is normal. **NEET-PG High-Yield Pearls:** * **Sillence Classification:** Used to grade OI (Type I is the most common and mildest; Type II is the most severe/lethal). * **Clinical Triad:** Blue sclera, fragile bones (multiple fractures), and early-onset otosclerosis (conductive hearing loss). * **Wormian Bones:** Often seen on skull X-rays in OI patients. * **Differential Diagnosis for Blue Sclera:** Apart from OI, it can be seen in Ehlers-Danlos Syndrome, Marfan Syndrome, and Pseudoxanthoma elasticum.

Question 1

What is the most common manifestation of osteoporosis?

Accepted Answer

Compression fracture of the spine

Answer

Asymptomatic, detected incidentally by low serum calcium

Answer

Bowing of legs

Answer

Loss of weight

Question 2

Albers-Schönberg disease is defined as which of the following conditions?

Accepted Answer

Osteopetrosis

Answer

Osteoporosis

Answer

Osteochondritis

Answer

Osteomalacia

Question 3

Paget's disease of bone can develop into which of the following malignancies after 10 years?

Accepted Answer

Osteosarcoma

Answer

Fibrous cortical defect

Answer

Osteoid osteoma

Answer

Ankylosing spondylitis

Question 4

Looser's zone occurs in all of the following conditions except?

Accepted Answer

Hypoparathyroidism

Answer

Osteomalacia

Answer

Paget's disease

Answer

Fibrous dysplasia

Question 5

In osteoporosis, what is observed?

Accepted Answer

Decrease in absolute amount of bone mass

Answer

More common in males

Answer

Radiographs show normal bone density

Answer

Hormonal replacement therapy

Question 6

Which of the following characteristics are TRUE or FALSE about osteopetrosis in a child? 1. Growth retardation 2. Mental retardation 3. Multiple fractures 4. Cataract 5. Hepatosplenomegaly

Accepted Answer

1, 3, 5 True & 2, 4 False

Answer

1, 3, 4 True & 2, 5 False

Answer

1, 3, 4 True & 5, 2 False

Answer

2, 3 False & 1, 4, 5 True

Question 7

A 4-year-old child presents with blue sclera and a history of multiple fractures following minimal trauma. For the mentioned disorder, select the serum concentrations of calcium and phosphate with which it is most likely to be associated.

Accepted Answer

Normal phosphate, normal calcium

Answer

Low phosphate, normal calcium

Answer

Low phosphate, high calcium

Answer

Normal phosphate, low calcium

Question 8

A 25-year-old female patient presented with anemia and seventh and eighth nerve palsy. Skull and spine X-rays revealed abnormalities consistent with a specific diagnosis. What is the diagnosis based on these findings?

Accepted Answer

Osteopetrosis

Answer

Paget's disease

Answer

Osteogenesis imperfecta

Answer

Osteomalacia

Question 9

Osteoporosis is caused by all of the following, except?

Accepted Answer

Oestradiol

Answer

Corticosteroid

Answer

Methotrexate

Answer

Chronic heparin therapy

Question 10

Blue sclera is a characteristic feature of which condition?

Accepted Answer

Osteogenesis imperfecta

Answer

Osteopetrosis

Answer

Cleidocranial dysostosis

Answer

Achondroplasia

Metabolic Bone Diseases — MCQs

Metabolic Bone Diseases — MCQs

On this page

Practice by Chapter

Want unlimited practice?