1. Question
A patient is admitted to the hospital with a diagnosis of primary
hyperparathyroidism. A nurse checking the patient’s lab results
would
... [Show More] expect which of the following changes in laboratory
findings?
o A. Elevated serum calcium
o B. Low serum parathyroid hormone (PTH)
o C. Elevated serum vitamin D
o 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.
o Option B: Parathyroid hormone levels may be high or
normal but not low. Patients with primary
hyperparathyroidism and other causes of PTHdependent 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.
o 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.
o 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. [Show Less]