Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (657 page)

   Vaginal swabs from rape victims.

   Limitations

   PAP is no longer used to screen for or to stage prostate cancer. In most instances, serum PSA is used instead.

   PAP measurement must not be regarded as an absolute test for malignancy, since other factors including benign prostatic hyperplasia, prostatic infarction, and manipulation of the prostate gland may result in elevated serum PAP concentrations.

   PAP measurements provide little additional information beyond that provided by PSA measurements.

Suggested Reading

Moul JW, Connelly RR, Perahia B, et al. The contemporary value of pretreatment prostatic acid phosphatase to predict pathological stage and recurrence in radical prostatectomy cases.
J Urol.
1998;159:935–940.

ACTH STIMULATION (COSYNTROPIN) TEST

   Definition

   Cosyntropin is synthetic ACTH (1–24), which has the full biologic potency of native ACTH (1–39). It is a rapid stimulator of cortisol and aldosterone secretion.

   Use

   This is the initial test used to distinguish primary from secondary adrenal insufficiency.

   It is not helpful in the diagnosis of Cushing syndrome. Several protocols are used to assess the response to exogenous ACTH administration (see below).

Low-Dose ACTH Stimulation Test

   This test involves physiologic plasma concentrations of ACTH and provides a more sensitive index of adrenocortical responsiveness.

   It is performed by measuring serum cortisol immediately before and 30 minutes after IV injection of cosyntropin in a dose of either 1 μg/1.73 m
²
or 0.5 μg/1.73 m
²
.

   There is no commercially available preparation of “low-dose” cosyntropin. The vials of cosyntropin currently available contain 250 μg and come with sterile normal saline to be used as a diluent. One prepares the low-dose solution of cosyntropin locally.