Hypercalcemia and Calcium Homeostasis
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Questions and Answers

What percentage of hypercalcemia cases are caused by malignancy?

  • 50%
  • 100%
  • 90% (correct)
  • 80%

    • What is the normal range of plasma calcium concentration?

  • 2.1-2.55 mmol/L (correct)
  • 2.6-3.0 mmol/L
  • 1.5-2.0 mmol/L
  • 3.5-4.0 mmol/L

    • What is the mechanism by which PTHrP causes hypercalcemia?

  • By stimulating bone formation
  • By inhibiting bone resorption
  • By increasing bone resorption and decreasing calcium excretion (correct)
  • By decreasing bone resorption and increasing calcium excretion

    • What is the term for the hypercalcemia caused by the production of PTHrP by some tumors?

    <p>Humoral hypercalcemia of malignancy</p> Signup and view all the answers

    Which of the following is a cause of hypercalcemia not related to malignancy or parathyroid disorder?

    <p>Hyperalbuminemia</p> Signup and view all the answers

    What is the term for the excessive production of parathyroid hormone?

    <p>Hyperparathyroidism</p> Signup and view all the answers

    What is the name of the syndrome caused by the production of PTHrP by some tumors?

    <p>Paraneoplastic syndrome</p> Signup and view all the answers

    What is the name of the hormone produced by some tumors that causes hypercalcemia?

    <p>PTH-related peptide (PTHrP)</p> Signup and view all the answers

    What is the cause of hypercalcemia in granulomatous diseases such as TB and sarcoidosis?

    <p>Macrophages producing excessive calcitriol</p> Signup and view all the answers

    Which of the following is NOT a symptom of hypercalcemia?

    <p>Fever</p> Signup and view all the answers

    What is the primary function of parathyroid hormone regulation?

    <p>Regulation of calcium levels</p> Signup and view all the answers

    Which of the following is a complication of hyperphosphatemia?

    <p>Hypocalcemia</p> Signup and view all the answers

    What is the diagnosis of primary hyperparathyroidism based on?

    <p>Elevated serum calcium and PTH levels</p> Signup and view all the answers

    What is the typical presentation of tumour lysis syndrome?

    <p>Hyperphosphatemia</p> Signup and view all the answers

    Which of the following is an example of paraneoplastic syndrome?

    <p>Hyperparathyroidism in malignancy</p> Signup and view all the answers

    What is the normal range of plasma calcium concentration?

    <p>0.74-1.52 mmol/L</p> Signup and view all the answers

    What is the primary stimulus for parathyroid hormone secretion?

    <p>Decreased calcium levels</p> Signup and view all the answers

    What is the primary function of the parathyroid hormone in calcium metabolism?

    <p>Regulation of calcium levels</p> Signup and view all the answers

    What is a common cause of hypercalcemia?

    <p>Hyperparathyroidism</p> Signup and view all the answers

    What is the term for the condition in which a tumor, usually in the lung or kidney, produces a substance that mimics the action of parathyroid hormone, leading to hypercalcemia?

    <p>Paraneoplastic syndrome</p> Signup and view all the answers

    What is the diagnosis of hyperparathyroidism often based on?

    <p>Laboratory results and imaging studies</p> Signup and view all the answers

    What is the term for the condition in which the parathyroid glands are underactive, leading to hypocalcemia?

    <p>Hypoparathyroidism</p> Signup and view all the answers

    What is the primary function of the parathyroid glands?

    <p>Regulation of calcium levels</p> Signup and view all the answers

    What is the term for the condition in which the parathyroid glands are overactive, leading to hypercalcemia?

    <p>Hyperparathyroidism</p> Signup and view all the answers

    Study Notes

    Calcium Homeostasis

    • Net effect of restoration of plasma phosphate to normal levels is independent of calcium levels.

    Hypercalcemia

    • Definition: Plasma calcium concentration >2.6mmol/L (normal range: 2.1-2.55mmol/L).
    • Causes:
      • Malignancy (90% of cases)
      • Hyperparathyroidism
      • Others (not related to malignancy or parathyroid disorder)
    • Pathogenesis of hypercalcemia in malignancy:
      • Metastasis of solid tumor to the bone, leading to increased bone resorption and release of calcium into the blood.
      • Production of PTHrP (PTH-related peptide) by some tumors, which acts like PTH and increases bone resorption and decreases calcium excretion in the urine.
    • Examples of malignancy-related hypercalcemia:
      • Solid neoplasm (carcinoma of breast, bone, bronchus, cervical, ovary, gut, kidneys)
      • Hematological malignancy (Multiple myeloma, lymphoma, and leukemia)

    Causes of Hypercalcemia

    • Hyperparathyroidism:
      • Primary hyperparathyroidism
      • Tertiary hyperparathyroidism
      • Multiple Endocrine Neoplasia (MEN)
    • Others:
      • Hyperalbuminemia (dehydration, venostasis)
      • Increased calcium intake/absorption (excess vitamin D intake, milk-alkali syndrome)
      • Increased bone resorption (thyrotoxicosis, prolonged bedridden)
      • Increased renal reabsorption (thiazide diuretics)
      • Chronic lithium therapy
      • Granulomatous disease (TB, sarcoidosis)

    Symptoms of Hypercalcemia

    • General:
      • Lethargy
      • Muscle weakness
      • Loss of weight
      • Impaired consciousness
      • Confusion
      • Drowsiness
      • Coma
      • Behavioral changes
    • Eyes:
      • Corneal and vascular calcification
    • CVS:
      • Hypertension
      • Cardiac arrhythmia
      • Aortic or mitral valve calcifications
    • GIT:
      • Nausea
      • Vomiting
      • Constipation
      • Peptic ulcer
      • Acute pancreatitis
      • Gallstones
    • Renal:
      • Polyuria
      • Polydipsia
      • Nephrolithiasis
    • Bone:
      • Bone pain due to fracture of weakened bones by osteoporosis

    Investigations for Hypercalcemia

    • Serum albumin
    • Serum calcium
    • Serum ALP
    • Renal profile
    • Thyroid function test (TFT)
    • PTH levels
    • Serum and urine electrophoresis
    • Vitamin D levels
    • Radioimaging: Skeletal survey

    Hypocalcemia

    • Definition: Plasma calcium concentration <1.52mmol/L (normal range: 0.74-1.52mmol/L).
    • Etiologies:
      • Haemolysed sample
      • CKD
      • Hypoparathyroidism
      • Pseudohypoparathyroidism
      • Vitamin D intoxication/excess
      • Excessive intake of phosphate
      • Increased tissue catabolism (hematological malignancy, post-chemotherapy)
      • Acromegaly

    Complications of Hyperphosphatemia

    • Increased phosphate levels inhibit hydroxylation of calcidiol in the kidney, leading to decreased calcitriol production and hypocalcemia.
    • Parathyroid diseases.

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    Description

    This quiz covers the definition and causes of hypercalcemia, a condition characterized by high plasma calcium concentration, as well as disorders of calcium homeostasis. Learn about the normal range of plasma calcium levels and the factors that contribute to hypercalcemia.

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