Disorder Of Ca Metabolism Flash Cards

Question 1

What are the main regulators of calcium metabolism?

Answer 1

Parathyroid hormone (PTH), vitamin D, and calcitonin.

Question 2

What is the normal serum calcium range?

Answer 2

8.5-10.5 mg/dL.

Question 3

What are the three forms of calcium in the blood?

Answer 3

Ionized calcium (active form), protein-bound calcium, and complexed calcium.

Question 4

What is the primary function of parathyroid hormone (PTH)?

Answer 4

Increases serum calcium by stimulating bone resorption, increasing renal reabsorption, and enhancing intestinal absorption via vitamin D activation.

Question 5

How does vitamin D regulate calcium?

Answer 5

Increases intestinal calcium and phosphate absorption and enhances bone mineralization.

Question 6

What is the role of calcitonin?

Answer 6

Lowers serum calcium by inhibiting bone resorption.

Question 7

What is the most common cause of hypercalcemia?

Answer 7

Primary hyperparathyroidism.

Question 8

What are the common causes of hypercalcemia?

Answer 8

Primary hyperparathyroidism, malignancy, granulomatous diseases, vitamin D toxicity, and thiazide diuretics.

Question 9

What is the classic clinical presentation of hypercalcemia?

Answer 9

Stones (kidney stones), bones (bone pain), groans (abdominal pain), thrones (polyuria), and psychiatric overtones (confusion, depression).

Question 10

What is the most common cause of primary hyperparathyroidism?

Answer 10

Parathyroid adenoma.

Question 11

What is the most common cause of secondary hyperparathyroidism?

Answer 11

Chronic kidney disease leading to phosphate retention and decreased vitamin D activation.

Question 12

What is tertiary hyperparathyroidism?

Answer 12

Autonomous parathyroid hyperplasia following prolonged secondary hyperparathyroidism, usually in end-stage renal disease.

Question 13

What is the treatment for primary hyperparathyroidism?

Answer 13

Parathyroidectomy in symptomatic patients or those with complications (osteoporosis, kidney stones).

Question 14

What is the mechanism of hypercalcemia in malignancy?

Answer 14

Ectopic PTH-related peptide (PTHrP) production or osteolytic bone metastases.

Question 15

What is the most common malignancy-associated with hypercalcemia?

Answer 15

Squamous cell carcinoma (lung, head and neck).

Question 16

What is milk-alkali syndrome?

Answer 16

Hypercalcemia, metabolic alkalosis, and renal failure due to excessive calcium and alkali ingestion.

Question 17

What are the ECG changes seen in hypercalcemia?

Answer 17

Shortened QT interval.

Question 18

What is the first-line treatment for severe hypercalcemia?

Answer 18

IV fluids and bisphosphonates.

Question 19

What is the mechanism of action of bisphosphonates?

Answer 19

Inhibits osteoclast-mediated bone resorption.

Question 20

What is the most common cause of hypocalcemia?

Answer 20

Hypoparathyroidism, vitamin D deficiency, chronic kidney disease.

Question 21

What are the clinical features of hypocalcemia?

Answer 21

Tetany, perioral numbness, muscle cramps, seizures, and prolonged QT interval.

Question 22

What is Chvostek’s sign?

Answer 22

Facial twitching when tapping the facial nerve, seen in hypocalcemia.

Question 23

What is Trousseau’s sign?

Answer 23

Carpal spasm induced by inflating a blood pressure cuff above systolic pressure, seen in hypocalcemia.

Question 24

What is the most common cause of hypoparathyroidism?

Answer 24

Post-surgical removal or damage to the parathyroid glands (thyroidectomy, parathyroidectomy).

Question 25

What is pseudohypoparathyroidism?

Answer 25

End-organ resistance to PTH despite normal or elevated PTH levels.

Question 26

What is the biochemical profile of pseudohypoparathyroidism?

Answer 26

Low calcium, high phosphate, and high PTH.

Question 27

What is Albright’s hereditary osteodystrophy?

Answer 27

A syndrome associated with pseudohypoparathyroidism, characterized by short stature, obesity, round face, and brachydactyly.

Question 28

What is the treatment for hypocalcemia?

Answer 28

IV calcium gluconate for severe cases; oral calcium and vitamin D for chronic cases.

Question 29

What is the role of magnesium in calcium metabolism?

Answer 29

Hypomagnesemia can cause hypocalcemia by impairing PTH secretion and action.

Question 30

What is the most common cause of vitamin D deficiency?

Answer 30

Inadequate sun exposure, malabsorption, or chronic kidney disease.

Question 31

What are the consequences of vitamin D deficiency?

Answer 31

Rickets in children and osteomalacia in adults.

Question 32

What is the biochemical profile of vitamin D deficiency?

Answer 32

Low calcium, low phosphate, high PTH, and low 25-hydroxyvitamin D levels.

Question 33

What is the recommended daily intake of vitamin D?

Answer 33

600-800 IU for adults; higher in elderly and deficient individuals.

Question 34

What are the clinical features of rickets?

Answer 34

Bowing of the legs, rachitic rosary (costochondral swelling), frontal bossing, and delayed growth.

Question 35

What are the features of osteomalacia?

Answer 35

Bone pain, muscle weakness, and pseudofractures on X-ray.

Question 36

What is the difference between osteoporosis and osteomalacia?

Answer 36

Osteoporosis is decreased bone mass with normal mineralization; osteomalacia is defective mineralization of bone.

Question 37

What is the treatment for vitamin D deficiency?

Answer 37

Vitamin D supplementation (cholecalciferol or ergocalciferol).

Question 38

What is the relationship between chronic kidney disease (CKD) and secondary hyperparathyroidism?

Answer 38

CKD leads to phosphate retention and reduced vitamin D activation, causing hypocalcemia and increased PTH secretion.

Question 39

What is renal osteodystrophy?

Answer 39

Bone disease caused by chronic kidney disease-associated secondary hyperparathyroidism.

Question 40

What is calciphylaxis?

Answer 40

A rare complication of CKD with calcification of blood vessels leading to painful skin necrosis.

Question 41

What is the function of fibroblast growth factor-23 (FGF-23)?

Answer 41

Regulates phosphate metabolism by reducing phosphate reabsorption and decreasing vitamin D activation.

Question 42

What is the function of RANKL in bone metabolism?

Answer 42

Promotes osteoclast differentiation and bone resorption.

Question 43

What is osteopetrosis?

Answer 43

A rare genetic disorder causing defective osteoclast function leading to increased bone density and fractures.

Question 44

What is the major cause of osteoporosis?

Answer 44

Postmenopausal estrogen deficiency or age-related bone loss.

Question 45

What is the first-line treatment for osteoporosis?

Answer 45

Bisphosphonates (alendronate, risedronate).

Question 46

What is the T-score cutoff for osteoporosis?

Answer 46

≤ -2.5 on dual-energy X-ray absorptiometry (DEXA) scan.

Question 47

What is Paget’s disease of bone?

Answer 47

A disorder of excessive bone turnover leading to structurally weak, deformed bones.

Question 48

What are the clinical features of Paget’s disease?

Answer 48

Bone pain, skull enlargement, hearing loss, and increased alkaline phosphatase.

Question 49

What is the first-line treatment for Paget’s disease?

Answer 49

Bisphosphonates (zoledronic acid, alendronate).

Question 50

What is tumor-induced osteomalacia?

Answer 50

A paraneoplastic syndrome where tumors produce FGF-23, causing phosphate wasting and bone softening.

Question 51

What is the effect of glucocorticoids on calcium metabolism?

Answer 51

Increases bone resorption, reduces calcium absorption, and induces osteoporosis.

Question 52

What is the role of denosumab in osteoporosis treatment?

Answer 52

A monoclonal antibody that inhibits RANKL to reduce bone resorption.

Question 53

What is the effect of chronic acidosis on bone?

Answer 53

Increases bone resorption and calcium release to buffer acidemia.

Question 54

What dietary measures help maintain bone health?

Answer 54

Adequate calcium, vitamin D, protein intake, and weight-bearing exercises.

Question 55

What is the main complication of untreated severe hypercalcemia?

Answer 55

Cardiac arrhythmias and acute kidney injury.