Reduction of Risk Potential Q 2
A patient is admitted to the hospital with a diagnosis of primary hyperparathyroidism. A nurse checking the patient’s lab results would expect which of the following changes in laboratory findings?
A. Elevated serum calcium
B. Low serum parathyroid hormone (PTH)
C. Elevated serum vitamin D
D. Low urine calcium
Correct Answer: A. Elevated serum calcium
The parathyroid glands regulate the calcium level in the blood. In hyperparathyroidism, the serum calcium level will be elevated. A normal PTH in the presence of hypercalcemia is considered inappropriate and still consistent with PTH-dependent hypercalcemia. PTH levels should be very low in those patients with PTH-independent hypercalcemia. A comprehensive clinical evaluation complemented by routine laboratory and radiologic studies should be sufficient to establish a diagnosis of primary hyperparathyroidism in a patient with persistent hypercalcemia and an elevated serum level of parathyroid hormone.
Option B: Parathyroid hormone levels may be high or normal but not low. Patients with primary hyperparathyroidism and other causes of PTH-dependent hypercalcemia often have frankly elevated levels of PTH, while some will have values that fall within the reference range for the general population. It is uncommon for clinically occult malignancies to cause hypercalcemia. Most patients with malignancy-associated hypercalcemia are known to have cancer, or cancer is readily detectable on initial evaluation, and PTH levels will be suppressed.
Option C: Parathyroid hormone levels may be high or normal but not low. The body will lower the level of vitamin D in an attempt to lower calcium.
Option D: Urine calcium may be elevated, with calcium spilling over from elevated serum levels. This may cause renal stones. A review of previous medical records can often be of significant value in establishing the cause of hypercalcemia. Most patients with hyperparathyroidism have persistent or intermittent hypercalcemia for many years before a definitive diagnosis is established.