Thyroidectomy Medical Question:
A patient undergoes successful thyroidectomy for Graves’ disease and returns to a euthyroid state with the use of levothyroxine supplementation. In a follow-up examination, the patient reports resolution of all prior symptoms except for anxiety and irritability. She also reports frequent muscle spasms. On physical examination, tapping over the facial nerve elicits facial muscle spasm. An ECG shows QT prolongation. Which of the following most likely describes the current laboratory values of this patient?
| CHOICE | CALCIUM | PHOSPHATE | PARATHYROID HORMONE |
| A | ↑ | ↓ | ↑ |
| B | ↑ | ↓ | ↓ |
| C | ↓ | ↑ | ↑ |
| D | ↓ | ↑ | ↓ |
| E | ↓ | ↓ | ↓ |
| F | Normal | Normal | Normal |
(A) A
(B) B
(C) C
(D) D
(E) E
(F) F
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The correct answer is D. Causes of hypoparathyroidism include thyroidectomy, metastatic cancer, and DiGeorge’s syndrome. Signs and symptoms of hypoparathyroidism include anxiety and irritability, neuromuscular excitability, tetany, intracranial calcifications, dental abnormalities, and cardiac conduction abnormalities. Laboratory values reflect a state of hypocalcemia and hyperphosphatemia with low parathyroid hormone levels. Parathyroid hormone increases the absorption of calcium from the gut and also concerts Vitamin D to its active form, which will both increase the calcium level. PTH also known as “Phosphate Trashing Hormone” helps the body to get rid phosphate through the kidneys.
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