Endocrine System: The Daily PANCE Blueprint
A 45-year-old woman presents to the emergency department with tingling sensations in her fingertips and around her mouth, as well as muscle cramps in her legs. Her medical history reveals that she underwent a total thyroidectomy 2 months ago. Her serum calcium level is 7.5 mg/dL (normal 8.5-10.2 mg/dL), and phosphate is 5.8 mg/dL (normal 2.5-4.5 mg/dL). An ECG shows a prolonged QT interval. Which of the following is the most likely diagnosis?
A. Hypocalcemia due to vitamin D deficiency
B. Hypoparathyroidism
C. Chronic kidney disease
D. Pseudohypoparathyroidism
E. Hyperparathyroidism
Answer and topic summary
The answer is B. Hypoparathyroidism
The patient’s symptoms of tingling, muscle cramps, hypocalcemia, hyperphosphatemia, and a prolonged QT interval on ECG are characteristic of hypoparathyroidism. This condition commonly occurs as a complication of thyroid surgery due to inadvertent damage or removal of the parathyroid glands. The patient’s recent thyroidectomy further supports hypoparathyroidism as the most likely diagnosis.
Explanation for Incorrect Answers:
- A. Hypocalcemia due to vitamin D deficiency: While vitamin D deficiency can cause hypocalcemia, it typically does not result in hyperphosphatemia, and the patient’s recent thyroidectomy points more specifically towards a surgical cause.
- C. Chronic kidney disease: CKD can lead to disturbances in calcium and phosphate metabolism, typically presenting as hyperphosphatemia and hypocalcemia. However, the history lacks other features of CKD such as anemia, azotemia, or changes in urine output.
- D. Pseudohypoparathyroidism: This genetic disorder mimics hypoparathyroidism but is distinguished by normal or increased parathyroid hormone (PTH) levels and a resistance to PTH’s effects. It would not typically occur as a result of surgery.
- E. Hyperparathyroidism: This condition would typically present with hypercalcemia and hypophosphatemia, opposite to the lab findings in this patient.
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Smarty PANCE Content Blueprint Review:
Covered under ⇒ PANCE Blueprint Endocrinology ⇒ ⇒
Also covered as part of the Internal Medicine EOR topic list
