Osteomalacia and Rickets — MCQs
A child presents with poor growth and swelling at joints. A radiograph of his wrist is given below. Lab investigations reveal serum ALP levels of >1500. What is the possible diagnosis?
The primary pharmacological intervention to retard avascular necrosis progression is?
A child presents with rachitic changes in the limbs that are not responding to Vitamin D supplementation. Investigations reveal the following results: - Calcium: $9.5 \mathrm{mg} / \mathrm{dl}$ - Phosphorus: $1.6 \mathrm{mg} / \mathrm{dl}$ - Alkaline phosphatase (ALP): 814 IU - Serum PTH: $24.2 \mathrm{pg} / \mathrm{ml}$ - Serum electrolytes, creatinine, and blood gases: Normal. What is the most likely diagnosis?
Which combination of features is most characteristic of nutritional rickets?
Secondary hyperparathyroidism due to Vit D deficiency shows :
All of the following statements are true except:
A 5-year-old female patient complains of a deformed shape of her legs. The patient is a strict vegetarian, and laboratory investigations reveal elevated levels of alkaline phosphatase. This patient may be suffering from a deficiency of:
The earliest evidence of Rickets is seen by:
A 70-year-old female has been on alendronate for 7 years for osteoporosis and now complains of pain in her right thigh. What is the next investigation to be performed?
Dietary deficiency of which vitamin is considered extremely rare?
Osteomalacia and Rickets Indian Medical PG Practice Questions and MCQs
Question 1: A child presents with poor growth and swelling at joints. A radiograph of his wrist is given below. Lab investigations reveal serum ALP levels of >1500. What is the possible diagnosis?
- A. Rickets (Correct Answer)
- B. Osteoporosis
- C. Osteomalacia
- D. Osteogenesis imperfecta
Explanation: ***Rickets*** - The combination of **poor growth**, **joint swelling**, and **elevated alkaline phosphatase (ALP)** in a child strongly indicates rickets, a condition of defective bone mineralization in growing bones. - The radiograph of the wrist would likely show typical findings like **widened growth plates**, **fraying** and **cupping of metaphyses**, and **decreased bone density**, which are characteristic of rickets. *Osteoporosis* - This condition is characterized by **reduced bone mass** and **fragile bones**, typically seen in older adults or due to secondary causes, and is not primarily linked to joint swelling in children. - While ALP levels can be normal or slightly elevated in osteoporosis, a level of >1500 is highly suggestive of active bone formation or breakdown, not typically seen in osteoporosis. *Osteomalacia* - This is defective bone mineralization in adults after growth plates have fused, leading to **bone softening** and **pain**, typically not presenting with joint swelling as a primary symptom. - While it also involves high ALP and bone demineralization, the clinical context of a *child* with growth issues points more specifically to rickets. *Osteogenesis imperfecta* - This is a group of **genetic disorders** characterized by **brittle bones** that fracture easily, often accompanied by **blue sclerae** and **hearing loss**, which are not mentioned in the presentation. - While bone fragility is present, it does not typically cause the described joint swelling or the significantly elevated ALP levels seen in this case.
Question 2: The primary pharmacological intervention to retard avascular necrosis progression is?
- A. High-dose calcium supplementation
- B. Vitamin D supplementation alone
- C. Corticosteroid therapy
- D. Bisphosphonates (Alendronate) (Correct Answer)
Explanation: ***Bisphosphonates (Alendronate)*** - **Bisphosphonates** inhibit osteoclast-mediated bone resorption and reduce bone cell death, showing promise in preventing progression of early-stage **avascular necrosis**. [1] - Alendronate specifically has been studied for its **bone-preserving effects** in AVN by maintaining bone architecture and potentially slowing femoral head collapse. *Corticosteroid therapy* - **Corticosteroids** are a major **risk factor** for developing avascular necrosis, not a treatment for it. - They cause AVN through mechanisms including **fat embolism**, increased **intraosseous pressure**, and direct **osteocyte toxicity**. *High-dose calcium supplementation* - **Calcium supplementation** supports general bone health but does not address the underlying **vascular disruption** in AVN. - No evidence exists that calcium alone can retard **AVN progression**, which involves interruption of blood supply leading to bone death. *Vitamin D supplementation alone* - **Vitamin D** is essential for calcium absorption and bone mineralization but does not target **AVN pathophysiology**. - Like calcium, it does not address the primary mechanism of **blood supply disruption** that characterizes avascular necrosis.
Question 3: A child presents with rachitic changes in the limbs that are not responding to Vitamin D supplementation. Investigations reveal the following results: - Calcium: $9.5 \mathrm{mg} / \mathrm{dl}$ - Phosphorus: $1.6 \mathrm{mg} / \mathrm{dl}$ - Alkaline phosphatase (ALP): 814 IU - Serum PTH: $24.2 \mathrm{pg} / \mathrm{ml}$ - Serum electrolytes, creatinine, and blood gases: Normal. What is the most likely diagnosis?
- A. Hypophosphatemic rickets (Correct Answer)
- B. Vitamin D-dependent rickets type 2
- C. Vitamin D-dependent rickets type 1
- D. Chronic renal failure
- E. Vitamin D deficiency rickets
Explanation: ***Hypophosphatemic rickets*** - The combination of **rachitic changes** not responding to Vitamin D, **low serum phosphorus (1.6 mg/dl)**, and **normal calcium and PTH levels** strongly points to hypophosphatemic rickets, a condition characterized by impaired renal phosphate reabsorption. - The **elevated alkaline phosphatase** indicates increased bone turnover as the body tries to mineralize bone despite phosphate deficiency. *Vitamin D-dependent rickets type 2* - This condition involves resistance to **1,25-dihydroxyvitamin D**, leading to **hypocalcemia** and elevated PTH, none of which are present here. - It would also typically show an inadequate response to Vitamin D, but the primary biochemical derangement is different. *Vitamin D-dependent rickets type 1* - This type is caused by a defect in **1-alpha-hydroxylase**, leading to an inability to convert 25-hydroxyvitamin D to its active form, resulting in **hypocalcemia** and elevated PTH, which are not observed. - It would also show a poor response to standard Vitamin D supplementation. *Vitamin D deficiency rickets* - This is the most common form of rickets caused by inadequate Vitamin D intake or synthesis, presenting with **hypocalcemia**, **elevated PTH**, and **low phosphorus**. - However, it typically responds well to Vitamin D supplementation, unlike the presentation here, and would show elevated PTH levels. *Chronic renal failure* - Chronic renal failure would present with **elevated creatinine**, and typically leads to **secondary hyperparathyroidism** (elevated PTH), **hyperphosphatemia**, and metabolic acidosis, none of which are suggested by the provided lab results. - The serum electrolytes, creatinine, and blood gases are explicitly stated as normal.
Question 4: Which combination of features is most characteristic of nutritional rickets?
- A. Widening of wrists, delayed dentition, muscle hypotonia, bowing of long bones (Correct Answer)
- B. Delayed dentition, muscle hypotonia, bowing of long bones
- C. Widening of wrists, delayed dentition, muscle hypotonia, bowing of long bones, early fontanelle closure
- D. Growth retardation only
Explanation: ***Widening of wrists, delayed dentition, muscle hypotonia, bowing of long bones*** - These are the classic and most characteristic signs of nutritional rickets, resulting from defective bone mineralization due to **vitamin D deficiency**. - **Widening of wrists** (epiphyseal enlargement), **delayed dentition**, **muscle hypotonia**, and **bowing of long bones** are all direct consequences of impaired calcium and phosphate deposition in growing bones. - This combination represents the most distinctive physical findings used for clinical diagnosis. *Delayed dentition, muscle hypotonia, bowing of long bones* - While these are indeed features of rickets, this option is incomplete as it omits the characteristic **widening of wrists** (epiphyseal enlargement). - Widening of wrists is one of the earliest and most diagnostic clinical signs of active rickets. *Widening of wrists, delayed dentition, muscle hypotonia, bowing of long bones, early fontanelle closure* - This option correctly lists several key features of rickets, but **early fontanelle closure** is incorrect. - Rickets typically causes **delayed fontanelle closure** due to impaired bone mineralization, not early closure. - Early fontanelle closure is associated with conditions like **craniosynostosis**, not rickets. *Growth retardation only* - While **growth retardation** can occur in severe rickets due to impaired bone development, it is too general and non-specific. - Many other conditions can cause growth retardation, and rickets presents with a distinct array of skeletal and muscular symptoms that are far more characteristic.
Question 5: Secondary hyperparathyroidism due to Vit D deficiency shows :
- A. Hypocalcemia (Correct Answer)
- B. Hypophosphatemia
- C. Hypercalcemia
- D. Hyperphosphatemia
Explanation: ***Hypocalcemia*** - **Vitamin D deficiency** leads to decreased intestinal absorption of calcium, causing **hypocalcemia** [3]. - This persistent **low serum calcium** is the primary stimulus for the parathyroid glands to increase PTH secretion, leading to secondary hyperparathyroidism [1], [2]. *Hypophosphatemia* - While PTH typically promotes phosphate excretion in the kidneys leading to hypophosphatemia, in **secondary hyperparathyroidism due to vitamin D deficiency**, the effect on phosphate can be variable [3]. - The goal of increased PTH is to raise calcium, and maintaining some level of phosphate is necessary for bone health and proper calcium regulation. Early or mild deficiency may not show significant hypophosphatemia. *Hypercalcemia* - **Hypercalcemia** is a characteristic feature of **primary hyperparathyroidism**, where the parathyroid glands autonomously overproduce PTH [1]. - In secondary hyperparathyroidism (due to vitamin D deficiency), the PTH is elevated in response to **low calcium**, and sustained significant hypercalcemia is not expected; in fact, the underlying problem is **hypocalcemia** [1]. *Hyperphosphatemia* - **PTH** generally acts to lower serum phosphate levels by promoting its renal excretion [2]. - Therefore, **hyperphosphatemia** is not typically observed in secondary hyperparathyroidism; rather, a more common finding would be normal or low phosphate due to the elevated PTH [3].
Question 6: All of the following statements are true except:
- A. 25–α hydroxylation takes place in liver
- B. 1–α hydroxylation takes place in kidney
- C. Daily requirement in the absence of sun–light is 450-600 IU/day
- D. 25(OH)D3 is the most active form of vitamin D (Correct Answer)
Explanation: ***25(OH)D3 is the most active form of vitamin D*** - This statement is incorrect. While **25(OH)D3 (calcifediol)** is the major circulating form of vitamin D, it is not the most active form. - The most active form of vitamin D is **1,25(OH)2D3 (calcitriol)**, which is formed by the 1-alpha hydroxylation of calcifediol in the kidneys. *25–α hydroxylation takes place in liver* - This statement is true. The initial hydroxylation of **vitamin D3 (cholecalciferol)** at the 25-position occurs in the liver, forming 25(OH)D3 (calcifediol). - This step is catalyzed by the enzyme **25-hydroxylase**. *1–α hydroxylation takes place in kidney* - This statement is true. The 25(OH)D3 produced in the liver is then transported to the kidneys, where it undergoes a second hydroxylation at the 1-alpha position. - This step, catalyzed by **1-alpha-hydroxylase**, forms the biologically active hormone 1,25(OH)2D3 (calcitriol). *Daily requirement in the absence of sun–light is 450-600 IU/day* - This statement is generally true. The recommended daily allowance (RDA) for vitamin D in adults, especially in the absence of sufficient sun exposure, typically ranges from **400 to 800 IU (international units)**, with 600 IU/day being a common guideline. - This requirement can vary based on age, geographical location, and other individual factors.
Question 7: A 5-year-old female patient complains of a deformed shape of her legs. The patient is a strict vegetarian, and laboratory investigations reveal elevated levels of alkaline phosphatase. This patient may be suffering from a deficiency of:
- A. Vitamin A
- B. Vitamin B1
- C. Vitamin C
- D. Vitamin D (Correct Answer)
Explanation: ***Vitamin D*** - **Vitamin D deficiency** in children leads to **rickets**, characterized by defective bone mineralization causing softened and weakened bones, resulting in **deformed legs** (e.g., bowed legs). - **Elevated alkaline phosphatase** is a common laboratory finding in rickets and osteomalacia, reflecting increased osteoblast activity attempting to mineralize uncalcified bone matrix. *Vitamin A* - **Vitamin A deficiency** can lead to **night blindness**, xerophthalmia, and impaired immune function, but not directly to bone deformities. - It plays a crucial role in vision, immune system function, and cell growth, not bone calcification. *Vitamin B1* - **Vitamin B1 (thiamine) deficiency** causes **beriberi**, affecting the cardiovascular (wet beriberi) and nervous systems (dry beriberi). - Symptoms include heart failure, peripheral neuropathy, and Wernicke-Korsakoff syndrome, which are unrelated to bone deformities. *Vitamin C* - **Vitamin C (ascorbic acid) deficiency** results in **scurvy**, characterized by impaired collagen synthesis. - Clinical signs include bleeding gums, petechiae, poor wound healing, and joint pain, but not primary bone deformities like bowed legs.
Question 8: The earliest evidence of Rickets is seen by:
- A. S. phosphorus level (Correct Answer)
- B. Radiological examination of growing end of bone
- C. S. calcium level
- D. S. alkaline phosphatase level
Explanation: ***S. phosphorus level*** - **Low serum phosphorus** is one of the **earliest biochemical markers** of rickets, appearing before radiological changes become evident. - Hypophosphatemia results from **inadequate vitamin D** leading to decreased intestinal absorption of phosphorus and/or increased renal phosphate wasting. - Biochemical abnormalities **precede radiological manifestations** in the natural progression of rickets. - This makes serum phosphorus measurement critical for **early detection** and intervention. *S. alkaline phosphatase level* - Elevated serum alkaline phosphatase is an important biochemical marker indicating increased osteoblastic activity. - However, it is **less specific** than serum phosphorus and may be elevated in other conditions affecting bone growth. - While it rises early in rickets, serum phosphorus changes are typically detected first. *Radiological examination of growing end of bone* - Radiological findings such as **widening of growth plates**, **cupping**, and **fraying** of metaphyses are characteristic of rickets. - However, these changes represent **established disease** rather than earliest evidence. - Radiological changes become visible only **after biochemical abnormalities** have been present for some time. - X-ray findings confirm the diagnosis but are not the earliest detectable changes. *S. calcium level* - **Serum calcium levels** are often maintained within normal range in early rickets due to compensatory mechanisms. - Increased **parathyroid hormone (PTH)** secretion mobilizes calcium from bone to maintain serum levels. - Hypocalcemia typically occurs only in **severe or late-stage** rickets when compensatory mechanisms fail.
Question 9: A 70-year-old female has been on alendronate for 7 years for osteoporosis and now complains of pain in her right thigh. What is the next investigation to be performed?
- A. DEXA scan
- B. Serum vitamin D levels
- C. Serum alkaline phosphate levels
- D. X-ray (Correct Answer)
Explanation: **X-ray** - Alendronate, a **bisphosphonate**, is associated with **atypical femoral fractures** after prolonged use, and an X-ray is the most appropriate initial investigation to visualize such a fracture. - Complaints of thigh pain in a patient on long-term bisphosphonate therapy should prompt imaging to rule out this serious complication. *DEXA scan* - A DEXA scan assesses **bone mineral density** but does not provide information about acute fractures or structural integrity in response to specific pain. - While it's used for osteoporosis diagnosis and monitoring, it won't directly identify an atypical femoral fracture. *Serum vitamin D levels* - Maintaining adequate **vitamin D levels** is important for bone health, but its measurement won't explain acute thigh pain or identify a fracture. - Low vitamin D levels can contribute to osteoporosis but are not the primary cause of pain suggestive of an atypical femoral fracture. *Serum alkaline phosphate levels* - **Alkaline phosphatase** levels can be elevated in conditions involving increased bone turnover, such as healing fractures or certain bone diseases. - However, it is not a direct diagnostic tool for identifying atypical femoral fractures and would not be the first line investigation.
Question 10: Dietary deficiency of which vitamin is considered extremely rare?
- A. Thiamine
- B. Vitamin B6
- C. Vitamin E (Correct Answer)
- D. Vitamin D
Explanation: ***Vitamin E*** - **Vitamin E deficiency** is exceptionally rare because it is a **fat-soluble vitamin** stored in the body and is widely available in many common foods. - Symptoms of deficiency, when they do occur, are usually seen in individuals with severe **malabsorption syndromes** or genetic abnormalities affecting its metabolism. *Vitamin B6* - **Vitamin B6 deficiency** can occur, especially in individuals with **alcoholism**, those taking certain medications, or with certain chronic diseases. - It can manifest with neurological symptoms, such as **neuropathy** and **seizures**, as well as dermatological issues. *Thiamine* - **Thiamine (Vitamin B1) deficiency** is a known problem in regions with poor nutrition and in chronic alcoholics. - It leads to conditions like **beriberi** (wet and dry) and **Wernicke-Korsakoff syndrome**, affecting the cardiovascular and nervous systems. *Vitamin D* - **Vitamin D deficiency** is common globally, particularly in populations with limited sun exposure or inadequate dietary intake. - It can cause **rickets** in children and **osteomalacia** in adults, impacting bone health.
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