Serum Calcium, Phosphate, and Related Topics MCQs
- Which of the following statements about serum calcium is not correct?
- A. Free or ionized calcium accounts for 50% of total calcium
- B. Protein bound calcium most of which is bound to globulins with only small portion bound to albumin. ✅
- C. Complex-bound calcium is bound to phosphates, citrate and bicarbonate.
- D. The protein-bound calcium accounts for 45% of the total calcium.
- Acidosis or a pH decrease, after the blood sample has been collected, causes a rise in ionized calcium because of the metabolic activity of the blood cells, a pH decrease by 0.1 leads to a reciprocal increase of ionized calcium by approximately:
- A. 0.05mmol/L ✅
- B. 0.10mmol/L
- C. 0.15mmol/L
- D. 0.20mmol/L
- Alkalosis or a rise in pH, after the blood collection, causes a decrease in ionized calcium due to the elimination of:
- A. Oxygen
- B. Hydrogen
- C. Carbon dioxide ✅
- D. Chloride
- This term refers to a state with serum total calcium concentration of typically >14 mg/dL that is associated with symptoms such as volume depletion, metabolic encephalopathy and gastrointestinal symptoms. As soon as the hypercalcemia has been eliminated, the symptoms disappear.
- A. Primary hyperparathyroidism
- B. Familial hypocalcemic hypercalcemia
- C. Hypercalcemic crisis ✅
- D. Milk-alkali syndrome
- Pseudohypoparathyroidism represents a group of states with end-organ resistance to PTH. Which of the following statements about pseudohypoparathyroidism is not correct?
- A. In type 1a, the gene that encodes the G protein is defective
- B. In type 1b, the PTH receptor is defective.
- C. In type 2, the urinary excretion of cAMP is increased in these patients. ✅
- D. Type 1 is characterized by a defect at a locus before the synthesis of cAMP while type 2 is associated with a defect at a locus beyond the synthesis of cAMP.
- Which of the following diseases may cause hypercalcemia?
- A. Liver cirrhosis
- B. Addison’s disease ✅
- C. Chronic renal failure
- D. Acute pancreatitis
- Which of the following diseases may cause hypocalcemia?
- A. Pseudohypoparathyroidism ✅
- B. Multiple myeloma
- C. Sarcoidosis
- D. Primary hyperparathyroidism
- Which formula is correct when adjusting total calcium if the albumin concentration is 4g/dL?
- A. Corrected calcium(mg/dL) = measured Ca (mg/dL)-albumin(g/dL) + 4.0 ✅
- B. Corrected calcium(mg/dL) = albumin(g/dL) – measured Ca (mg/dL) + 4.0
- C. Corrected calcium(mg/dL) = measured Ca (mg/dL)+albumin(g/dL) / 4.0
- D. Corrected calcium(mg/dL) = measured Ca (mg/dL)-albumin(g/dL) / 4.0
- How much increase in total calcium is anticipated in the case of a change from supine to a standing position?
- A. 4.6% ✅
- B. 1.7%
- C. 12%
- D. 5.4%
- How much increase in ionized calcium is anticipated in the case of a change from supine to a standing position?
- A. 4.6%
- B. 1.7% ✅
- C. 12%
- D. 5.4%
- Which of the following enzymes are used for phosphate measurement?
- 1. Purine-nucleoside phosphorylase
- 2. Xanthine oxidase
- 3. Sucrose phosphorylase
- 4. Phosphoglucomutase
- A. Only 1 and 3 are correct
- B. Only 2 and 4 are correct
- C. Only 1, 2, and 3 are correct
- D. 1, 2, 3, and 4 are correct ✅
- What is the molar ratio of HPO4/H2PO4?
- A. 1:1
- B. 1:2
- C. 1:3
- D. 1:4 ✅
- Which of the following conditions are associated with hypophosphatemia?
- 1. Bodybuilding
- 2. Alcoholism
- 3. Oncogenic osteomalacia
- 4. Diabetic ketoacidosis
- A. Only 1 and 3 are correct
- B. Only 2 and 4 are correct
- C. Only 1, 2, and 3 are correct
- D. 1, 2, 3, and 4 are correct ✅
- In the phosphate clearance test, the interval time for collection of two urine and blood samples is:
- A. 30 mins
- B. 60 mins ✅
- C. 90 mins
- D. 120 mins
- The percentage tubular reabsorption of phosphate, TRF%, is a test identical to the determination of the phosphate clearance but in addition this substance is measured in urine and serum:
- A. Inulin
- B. Urea
- C. Creatinine ✅
- D. Macroglobulin
