hypocalcemia Flashcards
Q: What is hypocalcemia?
A: Hypocalcemia refers to a serum calcium level below the lower limit of normal, often considered below 8.5 mg/dL.
Q: Why is calcium important in the body?
A: Calcium plays a vital role in cardiac muscle function and nerve signaling.
Q: What can calcium imbalances such as hypocalcemia result in?
A: Abnormal cardiac rhythm and neurologic dysfunction.
Q: What are some important causes of hypocalcemia?
A: Hypomagnesemia, impaired vitamin D conversion, hypoparathyroidism, and secondary hyperparathyroidism.
Q: What initial assessment should be performed if hypocalcemia is suspected?
A: Perform an ABCDE assessment to determine if the patient is unstable or stable.
Q: How should you stabilize an unstable hypocalcemic patient?
A: Stabilize airway, breathing, and circulation, obtain IV access, continuous vital sign monitoring, and provide supplemental oxygen if needed.
Q: What severe symptoms might a patient with hypocalcemia experience?
A: Laryngospasm, seizures, or a prolonged QT interval on an ECG.
Q: How do you treat severe hypocalcemia?
A: Administer intravenous calcium gluconate and consider giving IV magnesium.
Q: What should be done for stable patients with suspected hypocalcemia?
A: Obtain a focused history and physical examination, and order labs, including serum calcium and magnesium levels.
Q: What symptoms might a stable hypocalcemic patient report?
A: Numbness around the mouth, paresthesias of the fingers and toes, and emotional lability.
Q: What physical exam signs can indicate hypocalcemia?
A: Positive Chvostek or Trousseau signs.
Q: What is the Chvostek sign?
A: Tapping over the facial nerve muscles causes facial muscle spasms.
Q: What is the Trousseau sign?
A: Inflating a blood pressure cuff over the arm causes a spasm of the hand.
Q: Why should hypocalcemia be considered but not diagnosed immediately with low serum calcium levels?
A: Because half of the calcium in blood is bound to plasma proteins like albumin, and ionized calcium reflects the body’s stores more accurately.
Q: How do you calculate the corrected total serum calcium level?
A: Subtract serum albumin from 4, multiply the difference by 0.8, then add the product to the measured serum calcium.
Q: What should be checked after diagnosing hypocalcemia?
A: Review the serum magnesium level.
Q: What does low serum magnesium indicate in hypocalcemia?
A: Hypocalcemia due to magnesium deficiency, as magnesium is essential for PTH production.
Q: What labs should be ordered if serum magnesium is normal in hypocalcemia?
A: A basic metabolic panel, serum PTH, and 25-hydroxy vitamin D.
Q: What does elevated serum creatinine indicate in hypocalcemia?
A: Impaired conversion of vitamin D to its active form due to impaired renal function.
Q: What does low 1,25-dihydroxy vitamin D suggest?
A: Hypocalcemia due to impaired conversion of vitamin D to its active form.
Q: What should be checked if serum creatinine is normal in hypocalcemia?
A: Check PTH levels.
Q: What does low or normal PTH indicate in hypocalcemia?
A: Hypoparathyroidism, often iatrogenic or due to autoimmune disorders.
Q: What is autosomal dominant hypocalcemia?
A: A genetic disorder with a mutation in the calcium-sensing receptor causing low PTH secretion.
Q: How do you screen for autosomal dominant hypocalcemia?
A: Check urine calcium to creatinine ratio and consider genetic testing if elevated.
Q: What does elevated PTH indicate in hypocalcemia?
A: Secondary hyperparathyroidism, consider vitamin D deficiency or impaired vitamin D activity.
Q: What should be assessed if PTH is elevated in hypocalcemia?
A: Assess 25-hydroxy vitamin D levels.
Q: What does low 25-hydroxy vitamin D indicate?
A: Vitamin D deficiency.
Q: What should be considered if 25-hydroxy vitamin D is normal in hypocalcemia?
A: Pseudohypoparathyroidism, a rare genetic condition with end-organ resistance to PTH.
Q: How do you confirm a diagnosis of pseudohypoparathyroidism?
A: Order genetic testing.
Q: What is a common cause of secondary hyperparathyroidism?
A: Chronic kidney disease, leading to defects in vitamin D activation and resulting in hypocalcemia and hyperphosphatemia.
Q: What are some important causes of hypocalcemia?
A: Hypomagnesemia and impaired vitamin D conversion to its active form.
Q: What should be done if hypocalcemia due to magnesium deficiency is ruled out?
A: Assess PTH levels.
Q: What does low or normal PTH indicate?
A: Hypoparathyroidism.
Q: What does elevated PTH indicate?
A: Secondary hyperparathyroidism, assess 25-hydroxy vitamin D levels.
Q: What does normal 25-hydroxy vitamin D suggest in hypocalcemia?
A: Pseudohypoparathyroidism.
