A 47-year-old woman noticed a lump in her neck 1 week ago. On physical examination, there is a 2-cm nodule in the right lobe of the thyroid gland. A fine-needle aspiration biopsy is performed, and microscopic examination of the specimen shows cells consistent with a follicular neoplasm. She undergoes a subtotal thyroidectomy. Which of the following laboratory tests should be performed on this patient in the immediate postoperative period?

Correct Answer: C

Rationale: Inadvertent removal of or damage to the parathyroid glands during thyroid surgery can cause hypocalcemia secondary to hypoparathyroidism. This is the most common cause of hypoparathyroidism. Individuals with hypocalcemia exhibit neuromuscular irritability, carpopedal spasm, and sometimes seizures. Antithyroglobulin antibody levels are of no use in diagnosing surgical diseases of the thyroid. Calcitonin quantitative is not a useful measure to determine the status of calcium metabolism.

Correct Answer: A

Rationale: Hormones act via bloodstream, not synapses (neurotransmitters do); others are true: receptor specificity, gene expression, second messengers.

Correct Answer: A

Rationale: Isometric contraction: muscle tenses without shortening, as load exceeds force.

Correct Answer: A

Rationale: SV rises with EDV (preload) due to stretch; others are unrelated or opposite.

Correct Answer: D

Rationale: Hemorrhage reduces hydrostatic pressure; others compensate for blood loss.