Deck 14: Mineral and Bone Metabolism

Question 1

Which of the following electrolyte measurements would be of clinical usefulness to the clinician treating patients for pregnancy-induced hypertension?

A) Ionized calcium
B) Potassium
C) Magnesium
D) Phosphorus

Answer 1

Magnesium

Question 2

Which of the following statements best reflects the clinical usefulness for measuring Ionized or free calcium in blood?

A) It is the best indication of phosphate status because it is biologically active and tightly regulated by PTH and Vitamin D.
B) It is the best indication of calcium status because it is biologically active and tightly regulated by PTH and Vitamin D.
C) It is the best indication of calcium status because it is biologically inactive and tightly regulated by PTH and Vitamin D.
D) It is the best indication of calcium status because it is biologically active and tightly regulated by thyroid hormones.

Answer 2

It is the best indication of calcium status because it is biologically active and tightly regulated by PTH and Vitamin D.

Question 3

Which of the following blood drawing tubes is most appropriate for measuring magnesium?

A) Royal blue tube with K₂-EDTA
B) Lavender top tube with K₂-EDTA
C) Plain red top with no additives
D) Gray top tube with sodium fluoride/potassium oxalate

Answer 3

Plain red top with no additives

Question 4

Which of the following reagents is used to determine the concentration of serum magnesium?

A) Biuret
B) Bathophenanthroline
C) Methylthymol blue
D) Phosphomolybdate

Question 5

Monitoring intraoperative PTH is useful for:

A) Surgical management of primary hyperparathyroidism.
B) Surgical management of thyroid disease.
C) Surgical management of prostate cancer.
D) Surgical management of coronary heart disease.

Question 6

Blood levels of ionized calcium are sensitive to which of the following?

A) Barometric pressure
B) Partial pressure of carbon dioxide
C) Magnesium concentration
D) pH and temperature

Question 7

Which of the following additives is preferred when drawing blood samples to measure parathyroid hormone (PTH)?

A) Acid citrate dextrose because PTH is least stable using this additive
B) Potassium (3)-EDTA (K₃-EDTA) because PTH is most stable using this additive
C) Sodium citrate because PTH is most stable using this additive
D) Sodium fluoride/potassium oxalate because PTH will complex with oxalate to increase its stability

Question 8

Which of the following statements best illustrates the diagnostic criteria for primary hyperparathyroidism?

A) No serum PTH detected and no serum calcium detected
B) Detectable amounts of serum PTH concomitant with elevated total serum calcium
C) Elevated total serum calcium only
D) A normal level of serum PTH and serum calcium

Question 9

Which of the following feedback mechanisms regulate the production of 1, 25(OH) ₂D₃?

A) Negative feedback mechanism associated with circulating levels of calcium and inorganic phosphorus
B) Negative feedback mechanism associated with circulating levels of calcitonin
C) Negative feedback mechanism associated with circulating levels of magnesium
D) Positive feedback mechanism associated with circulating levels of calcium and inorganic phosphorus

Question 10

Which of the following is an effect of increased parathyroid secretion?

A) Decreased intestinal absorption of calcium
B) Increased intestinal absorption of calcium
C) Decreased blood calcium levels
D) Decreased bone resorption

Question 11

Which of the following laboratory results reflects a patient diagnosed with rickets as a result of a dietary deficiency of vitamin D?

A) Increased serum total calcium, decreased serum total alkaline phosphatase, and increased serum inorganic phosphorus
B) Decreased serum PINP, decreased serum TRAP, and decreased serum DPD
C) Normal serum PINP, normal serum TRAP, and normal serum DPD
D) Increased serum PINP, increased serum TRAP, and increased serum DPD

Question 12

Which of the following do calcium, phosphorus, and magnesium have in common?

A) They all exist in circulation as only free or ionized forms.
B) They all exist as free or ionized forms, bound to proteins and complexes to radicals, e.g., sulfates to form salts.
C) Calcium exists as bound and free only, phosphorus exists only as bound and complexes to radical to form salts and magnesium exists as free or ionized forms, bound to proteins and complexes to radicals to form salts.
D) Calcium blood levels are regulated by parathyroid hormones, phosphorus is regulated by testosterone, and magnesium is regulated by insulin.

Question 13

A blood specimen is received in the laboratory from a maternity patient in the obstetric unit with blood magnesium ordered by the attending physician. The serum magnesium level is 5.0 mg/dL (RI = 1.6 - 2.6 mg/dL). Which of the following explains the elevated serum magnesium?

A) The patient has primary hyperparathyroidism.
B) The patient has had a massive heart attack.
C) The patient is on magnesium sulfate intravenous infusion because she is experiencing pre-eclampsia.
D) The patient has Paget's disease.

Question 14

Which of the following is considered a significant problem with using biomarkers of bone turnover in the management of patients with osteoporosis in a clinical setting?

A) They can be repeated over short time intervals thus providing quick results.
B) They are noninvasive.
C) They require no special patient preparation.
D) The measurements are affected by several preanalytical variables both controllable and uncontrollable.

Question 15

Which of the following laboratory results best represents a patient with Paget's disease?

A) Decreased urinary hydroxyproline and increased serum alkaline phosphatase
B) Increased urinary hydroxyproline and decreased serum alkaline phosphatase
C) Normal urinary hydroxyproline and normal serum alkaline phosphatase
D) Decreased urinary hydroxyproline and decreased serum alkaline phosphatase

Question 16

"A progressive systemic skeletal disease characterized by low bone mass and micro architectural deterioration of bone tissue, with a consequent increase in bone fragility and susceptible to fracture" describes which of the following disorders?

A) Osteosarcoma
B) Osteoporosis
C) Renal osteodystrophy
D) Paget's disease

Question 17

Which of the following reagents is used in the colorimetric method to determine the concentration of calcium in serum?

A) Ehrlich's reagent
B) Cresolphthalein complexone
C) P-nitrophenylphosphate
D) Alkaline picrate

Question 18

Which of the following is an example of a controllable preanalytical variable associated with specimen collection for bone biomarker testing?

A) Diet
B) Age
C) Gender
D) Fractures

Question 19

Pyridinoline, carboxy, amino-terminal cross-linked telopeptide of type I collagen, and tartrate-resistant acid phosphatase are all examples of which of the following?

A) Biomarkers of osteoblast conversion to osteoclast
B) Biomarkers of formation
C) Biomarkers of resorption
D) Cancer antigens associated with bone tumors

Question 20

Which of the following compounds promote osteoclast formation?

A) Bisphosphonate
B) 1, 25-dihydroxy Vitamin D₃
C) Calcitonin
D) Osteoprotegerin {OPG}

Question 21

Heat inactivation and chemical inhibition are two methods used to measure which of the following analytes?

A) Acid phosphatase isoenzymes
B) Alkaline phosphatase isoenzymes
C) Creatine kinase isoenzymes
D) Osteocalcin

Question 22

Measuring RANK and/or RANKL may be clinically useful for assessing which of the following conditions?

A) Dwarfism
B) Bone fractures
C) Bone cancer
D) Shin splints

Question 23

Which of the following instruments can measure calcium, magnesium, and phosphorus in blood samples?

A) Fluorimeter
B) Osmometer
C) Atomic absorption spectrometer
D) Refractometer

Question 24

Biomarkers of bone formation include which of the following?

A) Hydroxproline
B) Carboxyl-terminal cross-linked telopeptide of type I collagen
C) Bone sialoprotein
D) Osteocalcin